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  • Articles  (190)
  • Column liquid chromatography  (82)
  • pharmacokinetics  (76)
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  • Articles  (190)
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  • Springer  (190)
  • American Chemical Society
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  • 1995-1999  (190)
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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of alternating silane copolymers: (Me2Si−R2Si−Me2Si) n (1995)
    Springer
    Journal of inorganic and organometallic polymers and materials 5 (1995), S. 217-236 
    Details
    ISSN: 1572-8870
    Keywords: Polysilane ; NMR ; pyrolysis ; randomization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bimodal molecular weight distributions of alternating copolymers of the type (Me2Si−R2Si−SiMe2) n , where R=hexyl and butyl, were obtained by polymerization of BrSiMe2−R2Si−Me2SiBr, using the Wurtz coupling method. Analysis of the samples by pyrolysis GC MS and solution29Si NMR indicated that some randomization occurred, due to cleavage of the original Si−Si bonds in the monomer. The extent of randomization was significantly greater in the high molecular weight fractions. Based on the nature of the rings from the py MGC/MS traces and the number on nonads found in the29Si spectra, two types of randomization processes have been proposed, involving backbiting followed by (1) ring expulsion or (2) redistribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01057894
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  • 2
    Electronic Resource
    Electronic Resource
    Direct hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexing (1995)
    Springer
    Journal of solution chemistry 24 (1995), S. 1249-1263 
    Details
    ISSN: 1572-8927
    Keywords: Hydrogen-1 ; carbon-13 ; nitrogen-15 ; NMR ; magnesiumisothiocyanate complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexation in aqueous mixtures has been completed. At temperatures low enough to slow proton and ligand exchange, separate1H,13C, and15N NMR signals are observed for coordinated and bulk water molecules and anions. The1H NMR spectra reveal signals for the hexahydrate and the mono-through triisothiocyanato complexes, as well as two small signals attributed to [Mg(H2O)5(OH)]1+ and [Mg(H2O)4(OH)(NCS)]. Accurate hydration numbers were obtained from signal area integrations at each NCS− concentration. In the15N NMR spectra, signals also were observed for the mono-through triisothiocyanato complexes, and a small signal believed to be due to [Mg(H2O)4(OH)(NCS)]. Coordination number contributions for NCS− were measured from these spectra and when combined with the hydration numbers they totalled essentially six at each anion concentration. Signals for [Mg(H2O)5(NCS)]1+ through [Mg(H2O)3(NCS)3]1− also were observed in the13C NMR spectra and the area evaluations were comparable to the15N NMR results. An analysis of the magnitude and sign of the coordinated NCS− chemical shifts identified the nitrogen atom as the anion binding site. All spectra indicated [Mg(H2O)5(NCS)]1+ and [Mg(H2O)4(NCS)2] were the dominat isothiocyanato complexes over the entire range of anion concentrations. The inability to detect evidence for complexes higher than the triisothiocyanato reflects the competitive binding ability of water molecules and perhaps the decreased electrostatic interaction between NCS− and negatively charged higher complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972831
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of malondialdehyde as an index of lead damage in rat brain homogenates (1995)
    Springer
    BioMetals 8 (1995), S. 275-279 
    Details
    ISSN: 1572-8773
    Keywords: lead ; lipid peroxidation ; pro-oxidant ; anti-oxidant ; rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Lipid peroxidation in vitro homogenates of brain was examined as sequela of lead toxicity. The levels of malondialdehyde (MDA) in homogenates of rat brain (1 ml, 5% w/v) treated with lead (50 μg) alone or in combination with ascorbic acid (100 μg), alphatocopherol (100 μg) or hydroquinone (100 μg) were evaluated. The levels of MDA were consistently evoked by lead in a dose-related manner. The toxicity of lead was further advanced by the action of the pro-oxidant drug ascorbic acid on the brain. However, the anti-oxidant drugs alphatocopherol and hydroquinone decreased the toxic effect of lead on the brain. These results clearly show that the enhanced lipid peroxidation may provide a basis of lead-induced neurotoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00141599
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  • 4
    Electronic Resource
    Electronic Resource
    The steric structure of multiflorine methylation products (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 233-239 
    Details
    ISSN: 1434-4475
    Keywords: Enaminoketones ; Lupin alkaloid ; Multiflorine ; NMR ; Nucleophilic methylation ; Stereospecificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Multiflorin (1), ein Lupin-Nebenalkaloid, ergibt bei Umsetzung mit Methyllithium oder Methylmagnesiumiodid 4S-4-Hydroxy-4-methyl-2,3-didehydrospartein (2) und 2S-2-Methyl-4-oxospartein (3) als Hauptprodukte. Ihre NMR-spektroskopisch (1H und13C) aufgeklärte räumliche Struktur weist auf eine Stereoselektivität der erwähnten Reaktionen hin. Die beobachteten nucleophilen 1,2- und 1,4-Additionen zeigen, daß sich die Regiospezifität der Einwirkung von MeLi oder MeMgl auf Multiflorin von jener bis jetzt bekannter Alkylierungen von Enaminoketonen unterscheidet.
    Notes: Summary Multiflorine (1) — a minor lupine alkaloid — treated by methyl lithium or methyl magnesium iodide affords 4S-4-hydroxy-4-methyl-2,3-didehydrosparteine (2) and 2S-2-methyl-4-oxosparteine (3), respectively, as the dominating products. Their steric structure, determined by1H and13C NMR techniques, points to stereospecific preferences of these reactions. The observed nucleophilic 1,2- and 1,4-additions indicate that regiospecificity of the action of MeLi or MeMgI on multiflorine is different from that of the so far known similar alkylation of other enamino ketones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00812252
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and stereochemistry of 8-methyl-5-nitro-1-octalones (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 1011-1019 
    Details
    ISSN: 1434-4475
    Keywords: Precursors of strigol analogues ; Michael reaction ; NMR ; Molecular modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung BasenkatalysierteMichael-Addition von 5-Nitropentan-2-on-ethylenketal (1) und Cyclohex-2-enon (2), anschließende Entfernung der Schutzgruppe und darauffolgende Aldolkondensation liefert isomer 8-Methyl-5-nitro-1-octalone (5a,b). Struktur, relative Konfiguration und Konformation von5a und5b wurden mittels1H- und13C-NMR-Spektroskopie aufgeklärt.
    Notes: Summary Base catalyzedMichael addition of 5-nitropentan-2-one ethylene ketal (1) and cyclohex-2-enone (2), subsequent deprotection, and intramolecular aldol condensation yields the 8-methyl-5-nitro-1-octalone isomers (5a,b). The structure, relative configuration, and conformation of5a and5b were elucidated utilizing the results of1H and13C NMR investigations
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811021
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of aluminum rich MCM-41 (1995)
    Springer
    Catalysis letters 31 (1995), S. 267-272 
    Details
    ISSN: 1572-879X
    Keywords: MCM-41 synthesis ; NMR ; FTIR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of MCM-41 mesoporous compounds with Si/Al ratios as low as 2 without observing the presence of octahedral Al in27AlMAS NMR is reported. FTIR spectra of chemisorbed pyridine indicated that MCM-41 materials in their protonated form exhibit both Brønsted and Lewis acid sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808839
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  • 7
    Electronic Resource
    Electronic Resource
    Methotrexate in juvenile rheumatoid arthritis (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 507-511 
    Details
    ISSN: 1432-1041
    Keywords: Methotrexate ; Juvenile rheumatoid arthritis ; pharmacokinetics ; age dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Children with juvenile rheumatoid arthritis (JRA) have been reported to require higher doses (per kg body weight) of methotrexate (MTX) than adults with rheumatoid arthritis to control their disease. The purpose of the present study was to characterise the plasma pharmacokinetics of MTX and its major metabolite, 7-hydroxymethotrexate (7-OHMTX) in children, and to compare the results with those previously obtained in adults. Thirteen patients (age 5–16 y) with JRA (median disease duration 5.5 y) were studied after once weekly oral administration of MTX (median 0.21 mg·kg−1). The analytical method was sufficiently sensitive to permit determination of plasma and urinary concentrations of MTX and 7-OHMTX during the entire dose interval in most of the patients. The dose normalized area under the plasma concentration versus time-curve (AUC) of MTX increased with the age of the children and was lower than previously found in adults. The dose normalized AUC of 7-OHMTX was not dependent on age. No correlation was found between the AUCs of MTX and 7-OHMTX. The results suggest that the age-dependence of the pharmacokinetics of MTX might explain the observation that at least some children require higher doses of MTX than adults to obtain a sufficient therapeutic effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193703
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  • 8
    Electronic Resource
    Electronic Resource
    Antipyrine disposition in obesity: evidence for negligible effect of obesity on hepatic oxidative metabolism (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 525-530 
    Details
    ISSN: 1432-1041
    Keywords: Antipyrine disposition ; Obesity ; pharmacokinetics ; oxidative metabolism ; weight reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Following an overnight fast and 2 days of abstention from caffeine, a single 1.0-g oral dose of antipyrine was administered to 20 obese but otherwise healthy subjects (group A) and 11 healthy volunteers (group B). Weight, Body Mass Index (BMI) and % of Ideal Body Weight (IBW) were significantly greater in the obese than in the lean group. (Mean 110.4 vs 62.7 kg; 38.5 vs 22.3 kg · m−2 and 181vs 106 % respectively). In a subgroup of 6 obese subjects (group C) antipyrine was given again 11.3 months later after a 29.8 kg mean weight loss. Antipyrine apparent volume of distribution (V) and elimination half-life (t 1/2) were significantly greater in the obese than in the lean group (V 49.9 vs 34.3 l respectively; t 1/2 15.5 vs 12.0 h respectively), but its clearance rate (CLo) values were similar. V corrected for total body weight was significantly reduced in group A than in group B (0.45 vs 0.55 l · kg−1 respectively). Stratified comparison of antipyrine pharmacokinetics between obese and lean subjects according to age, gender and smoking habits did not alter the overall results. In group C, weight reduction was associated with a significant decrease in antipyrine V (from 51.8 to 47.5 l) and t 1/2 (from 15.1 to 12.7 h), and a non-significant increase in antipyrine CLo. We conclude that in severely obese subjects, antipyrine total V is mildly increased but V corrected for total body weight is significantly decreased. In addition, obesity is associated with a slight prolongation of antipyrine t 1/2 whereas its CLo is unaltered. These findings may indicate that obesity, even in its extreme form, has a negligible effect on the oxidative metabolic capacity of the liver.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193706
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  • 9
    Electronic Resource
    Electronic Resource
    Oral bioavailability of CHF1194, an inclusion complex of piroxicam and β-cyclodextrin, in healthy subjects under single dose and steady-state conditions (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 531-536 
    Details
    ISSN: 1432-1041
    Keywords: Piroxicam ; β-Cyclodextrin ; pharmacokinetics ; healthy volunteers ; multiple dose ; adverse event
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract CHF1194 is an inclusion complex of β-cyclodextrin with the nonsteroidal anti-inflammatory drug piroxicam. In man, β-cyclodextrin acts as a carrier of piroxicam. As the inclusion complex of piroxicam-β-cyclodextrin is wettable and more water soluble, the absorption rate of the drug is increased whilst its other pharmacokinetic characteristics remain unchanged. The aim of the present study in 12 healthy subjects was to compare the oral bioavailability of 20 mg piroxicam in a CHF1194 tablet and a plain piroxicam capsule after a single dose and after two weeks of once daily administration, and also to assess the plasma levels and urinary excretion of β-cyclodextrin after CHF1194 administration. The two treatments were administered in cross-over fashion, separated by a wash-out period of three weeks. Piroxicam, 5′-hydroxypiroxicam and β-cyclodextrin were monitored in plasma and urine for 120 h after the first and last doses. Clinical tolerance was excellent and no adverse event occurred during either phase of the study. The extent of absorption of piroxicam from the CHF1194 tablet after the single dose was equivalent to that after the plain piroxicam capsule, within confidence limits of less than 80–125%. After repeated dosing, CHF1194 yielded the same steady-state systemic concentrations of piroxicam and 5′-hydroxypiroxicam as the reference capsule, and similar excretion pattern of the metabolite. After both single and multiple dosing, piroxicam was absorbed more rapidly after CHF1194, an expected consequence of the complexation of piroxicam with β-cyclodextrin. This may be of therapeutic interest as it might accelerate the onset of pain relief. The pharmacokinetics of piroxicam was linear after the doses used here, suggesting that long term treatment with CHF1194 should not require any change in dosing regimen. Even after 14 days of repeated administration of CHF1194, β-cyclodextrin could not be detected in plasma or urine, suggesting that in man the unchanged oligosaccharide was absorbed to a very small extent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193707
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  • 10
    Electronic Resource
    Electronic Resource
    Furosemide disposition in patients on CAPD (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 385-390 
    Details
    ISSN: 1432-1041
    Keywords: Furosemide ; Dialysis ; continuous ambulatory peritoneal ; drug disposition ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Single doses of oral and intravenous furosemide were given to 8 healthy male volunteers (40 mg) and 11 patients with renal failure maintained on continuous ambulatory peritoneal dialysis (CAPD) (80 mg). In the volunteers, absorption was variable. Only one half of the intravenous dose and one third of the oral dose was available for renal pharmacological action as judged by the urinary recovery. In the patients, absorption was also variable and was markedly delayed (t max 128 vs 90 min) but more complete (bioavailability 70.1 vs 53.6%). The differences between the two groups were not significant, however (95% C.I.: -90 to 30 and -40.4 to 7.5 respectively). The mean elimination half-life was significantly longer in the patients following both the oral (228 vs 65.1 min) and intravenous dose (195 vs 60.3 min). The total body clearance of furosemide in the volunteers was 138 ml·min−1 and this was much lower in the CAPD patients (61.9 ml·min−1) in whom the renal clearance was minimal. The peritoneal clearance of furosemide was negligible. Although there were trends indicating differences in absorption between the two groups, the significant differences in furosemide disposition observed in CAPD patients were due to renal failure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194955
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  • 11
    Electronic Resource
    Electronic Resource
    Effects of altitude (4300 M) on the pharmacokinetics of caffeine and cardio-green in humans (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 167-170 
    Details
    ISSN: 1432-1041
    Keywords: Caffeine ; Cardio-green ; Indocyanine Green ; altitude ; metabolism ; pharmacokinetics ; hypoxia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The effects of chronic exposure to high altitude on the pharmacokinetics of caffeine and cardiogreen (ICG) were examined in eight healthy males (23–35 y) at sea level (SEA) and following 16 days residence at 4300 m (ALT). ICG (0.5 mg · kg−1) was administered as an intravenous bolus and caffeine (4 mg · kg−1) in an orally ingested solution. The concentration of ICG, caffeine, and the primary metabolites of caffeine (MET) were determined in serial blood samples and their pharmacokinetics computed. In comparison to SEA, ALT resulted in a significant decrease in the caffeine half-life (t1/2, 4.7 vs 6.7 h) and area under the curve (2.5 vs 3.7 g · 1−1 · min−1), and increased clearance (117 vs 86 ml · min−1 · 70 kg−1). In ALT the area under the curve of ICG significantly decreased (85 vs 207 mg · 1−1 · min−1) and the volume of distribution and clearance increased (5.2 vs 2.41 and 532 vs 234 ml · min−1 respectively) compared to SEA. There was a significant increase in the AUC ratio of MET to caffeine indicating that either metabolite formation or elimination was increased in ALT. These results demonstrate that in humans, chronic exposure to 4300 m results in the modification of the pharmacokinetics of caffeine and ICG.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192744
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  • 12
    Electronic Resource
    Electronic Resource
    Pharmacokinetics and bioavailability of a sustained-release diltiazem formulation (Mono-Tildiem LP 300 mg) after repeated administration in healthy volunteers (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 259-264 
    Details
    ISSN: 1432-1041
    Keywords: Diltiazem ; sustained-release formulation ; pharmacokinetics ; bioavailability ; bioequivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The usual dosage regimen of diltiazem (Tildiem) is 60 mg 3–4 times a day. A sustained-release formulation has been developed (Mono-Tildiem LP 300 mg) in order to allow a single daily administration. Two repeated dosing studies were performed in healthy volunteers. The absolute bioavailability of sustained-release diltiazem LP 300 mg was investigated using concomitant i.v. administration of 13C-labelled drug: absolute bioavailability of the “once a day” formulation was 35%. The second study compared sustained-release diltiazem LP 300 mg with the standard formulation of diltiazem. The results showed that the diltiazem plasma concentrations obtained after the LP formulation remained stable between 2 and 14 h after administration and were compatible with a once a day administration. Relative bioavailability of sustained-release diltiazem LP 300 mg was 79.3% compared with diltiazem. Therefore, a unitary dose of sustained-release diltiazem LP 300 mg was chosen as the dose equivalent to the daily dose administered with the standard diltiazem formulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198308
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  • 13
    Electronic Resource
    Electronic Resource
    Disposition of lorazepam in diabetes: differences between patients treated with beef/pork and human insulins (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 253-258 
    Details
    ISSN: 1432-1041
    Keywords: Diabetes ; Human insulin ; Lorazepam ; pharmacokinetics ; glucuronidation ; enterohepatic circulation ; animal insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetics of lorazepam was examined in 10 male patients with insulin-dependent diabetes mellitus before and following treatment with neomycin and cholestyramine. Neomycin and cholestyramine were given in an attempt to block the enterohepatic circulation of lorazepam and so to permit an in vivo estimate of hepatic glucuronidation. The volume of distribution and clearance of free lorazepam in diabetic patients were not significantly different from the corresponding estimates in 14 normal controls. Neomycin and cholestyramine increased the clearance of lorazepam by 63% consistent with their effect in non-diabetic controls. However, patients on beef/pork insulin exhibited a greater than normal increase on this interupting regimen (125%), and had a significantly greater neomycin/cholestyramine cycling-interrupted clearance of lorazepam than either normal controls or patients on human insulin (15.4 vs. 6.96 and 7.87 ml·min−1·kg−1). The clearance was correlated positively and significantly with HbA1c and glycated proteins (fructosamine), but only in patients on human insulin. Thus, the pharmacokinetics of lorazepam was not altered in patients with insulin-dependent diabetes mellitus. However, it is possible that there are differences in the rate and extent of hepatic glucuronidation and enterohepatic circulation of lorazepam between patients treated with beef/pork and human insulins and between diabetics treated with beef/pork insulin and non-diabetic controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198307
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  • 14
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of 5-aminosalicylic acid from controlled-release capsules in man (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 273-277 
    Details
    ISSN: 1432-1041
    Keywords: Mesalamine ; 5-aminosalicylic acid ; controlled release capsules ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract One gram single dose of Pentasa controlled-release capsules was administered to 24 healthy volunteers under fasting condition. Mean plasma 5-aminosalicylic acid (5-ASA) and acetyl 5-ASA concentrations peaked at 0.53 μg · ml−1 and 1.33 μg · ml−1 from 3 to 4 hours following dosing, respectively. The half-lives of both compounds could not be determined as absorption of 5-ASA was continuous throughout the gastrointestinal tract. An average of 29.4% (CV: 27%) of the dose was excreted in the urine primarily as acetyl 5-ASA. Up to 91.1% of the dose was released from the capsules. Forty percent of the dose (CV: 40%) was eliminated in the feces, with 8.9% of the dose remained as formulation bounded 5-ASA, indicating that controlled-release capsules continue to release drug throughout the GI tract. 5-ASA contributed 46.7% of the salicylates eliminated in the feces and acetyl 5-ASA accounted for the balance. Controlled-release capsules produced three times more total salicylates and 10 times more total and free 5-ASA in the feces than did 5-ASA suspension. Thus, while lower systemic levels of salicylates were absorbed, greater therapeutic quantities of 5-ASA were available in the bowel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198311
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  • 15
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of thiopental after single and multiple intravenous doses in critical care patients (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 127-137 
    Details
    ISSN: 1432-1041
    Keywords: Thiopental ; Pharmacokinetic modelling ; pharmacokinetics ; single dose ; multiple dosing ; neurosurgical patients ; variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Thiopental was administered to neurosurgical patients for cerebral protection and its pharmacokinetic parameters were determined after a single bolus of 540, 1000 or 1500 mg (3 subjects) or after multiple doses of 250 mg (5 subjects) and 500 mg (2 subjects) every two hours for up to 7 days. The data were analysed by a two- or three- compartment model and linear kinetics. After a single IV bolus, the mean initial volume of distribution (V1) was 0.4811·kg−1, and the steady-state volume of distribution (Vss) was 2.16 1·kg−1. The distribution (t1/2α) and elimination (t1/2β) half-lives were 0.590 and 5.89 h, respectively, and the mean residence time (MRT) was 7.44 h. The clearance was 5.41 ml·min−1·kg−1. With repeated injections, the pharmacokinetic parameters for each patient were estimated taking into account all administered doses and blood samples, which were taken whenever possible daily at steady state and after the last dose. The variability observed in the pharmacokinetic parameters of thiopental reflected by the coefficient of variation (CV%) was wide but was of similar magnitude within patients (CVintra) as it was between patients (CVinter). The steady-state trough plasma concentration (Cmin obs) ranged from 4.8 to 30 mg·1−1 (mean 16.0 mg·1−1 and median 14.3 mg·1−1). Peak concentrations (Cmax obs) ranged from 8.35 to 45 mg·1−1 (25.4 mg·1−1, and median 23.3 mg·1−1). The values of V1 and Vss were similar to those obtained after a single dose. For V1, the mean was 0.333 1·kg−1. The mean Vss was 2.68 1·kg−1, with a CVintra of 12.6 to 56% and a CVinter of 13.2%. A shorter distribution half-life t1/2α was noted on multiple dosing; the mean value was 0.122 h. The elimination half-life t1/2β and the mean residence time became longer due to a decrease in clearance. For t1/2β the mean value was 16.3 h. The mean MRT was 21.9 h, CVintra 9.19 to 48.5%, and the CVinter 35.3%. The mean clearance was 2.16 ml·min−1·kg−1, CVintra 7.28 to 25.5%, and the CVinter 20.4%. This value is 50% lower than after a single dose. Identification of the kinetic parameters of thiopental allows simulation of the effects of doses on subsequent plasma levels and will permit a priori prediction of day to day adjustment of drug dosage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192371
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  • 16
    Electronic Resource
    Electronic Resource
    Limitations of the maximum entropy principle in devising drug input rate (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 139-143 
    Details
    ISSN: 1432-1041
    Keywords: Intestinal absorption ; Amoxicillin ; pharmacokinetics ; maximum entropy ; input rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract A computer program applying the principle of maximum entropy to the analysis of drug absorption rate has been developed. Plasma concentrations of amoxicillin obtained after oral and intravenous dosing have been analysed, together with simulated data corresponding to a complex input. Amoxicillin absorption rates devised by the program were similar to those obtained by a standard deconvolution method, although they were displayed as an almost continuous profile. However, improbable fluctuations were obtained with some data sets and the fraction absorbed was underestimated by 13%. With the simulated data, the maximum entropy program did not provide a better solution than the standard deconvolution procedure, and it was sensitive to the addition of random error and to the number of samples. The maximum entropy principle, as implemented in our computer program, may not have a better performance than standard deconvolution procedures, especially in human experiments where the number of blood samples is usually limited.
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    Single dose pharmacokinetics of sumatriptan in healthy volunteers (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 543-548 
    Details
    ISSN: 1432-1041
    Keywords: Sumatriptan ; pharmacokinetics ; single dose ; bioavailability ; dose proportionality ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Sumatriptan is classified as a vascular 5HT1 receptor agonist and is effective in the acute treatment of migraine and cluster headache. Sumatriptan is available as an injection for subcutaneous administration and as a tablet for oral administration. The pharmacokinetics of sumatriptan differ depending on the route of administration. The mean subcutaneous bioavilability is 96% compared to 14% for the oral tablet. The lower bioavailability following oral administration is due mainly to presystemic metabolism. The inter-subject variability in plasma sumatriptan concentrations is greater following oral administration and a faster rate of absorption of drug into the systemic circulation is achieved following subcutaneous dosing. The pharmacokinetics of sumatriptan are linear up to a subcutaneous dose of 16 mg. Following oral dosing up to 400 mg, the pharmacokinetics are also linear, with the exception of rate of absorption, as indicated by a dose dependent increase in time to peak concentration. Sumatriptan is a highly cleared compound that is eliminated from the body primarily by metabolism to the pharmacologically inactive indoleacetic acid analogue. Both sumatriptan and its metabolite are excreted in the urine. Although the renal clearance of sumatriptan is only 20% of the total clearance, it exceeds the glomerular filtration rate, indicating that sumatriptan undergoes active renal tubular secretion. Sumatriptan has a large apparent volume of distribution (170 1) and an elimination half-life of 2 h. Oral doses of sumatriptan were administered as a solution of dispersible tablets and subcutaneous dosing was by injection into the arm. In clinical practice, sumatriptan is administered as a film coated tablet or by subcutaneous injection into the thigh.
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    URL: http://dx.doi.org/10.1007/BF00193709
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  • 18
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    The pharmacokinetics of granisetron, a 5-HT3 antagonist in healthy young and elderly volunteers (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 519-520 
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    ISSN: 1432-1041
    Keywords: Granisetron ; pharmacokinetics ; elderly ; tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194344
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  • 19
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    Pharmacokinetics and pharmacodynamics of a single dose of recombinant human growth hormone after subcutaneous administration by jet-injection: comparison with conventional needle-injection (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 69-72 
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    ISSN: 1432-1041
    Keywords: Growth hormone ; Jet-injection ; pharmacokinetics ; pharmacodynamics ; Somatomedin C ; free fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetics and pharmacodynamics of recombinant human growth hormone (rhGH) were studied after a single subcutaneous dose given by jet-injection, and have been compared with the results obtained after conventional needle-injection. Twelve healthy male volunteers completed an open label, randomised, two-way crossover study, with a 7-day washout period between the two single sc doses. Pharmacokinetic parameters were derived from rhGH concentrations in blood samples collected regularly over 24 h after dosing on Day 1 of each period. To investigate the pharmacodynamics, additional samples were taken for the analysis of somatomedin C (IGF-I) and free fatty acids (FFA). A higher and earlier Cmax was found after jet-injection (ratio (%) jet-injected/needle-injected 124; 90%-confidence interval 108 – 142). The AUC0−∞ for rhGH were similar (ratio (%) jet-injected/needle-injected 98; 90%-confidence interval 93 – 103). Both treatments were associated with a significant and similar rise in IGF-I. Both administrations of rhGH were associated with identical rhythmical changes in FFA. The study indicates that jet-injected and needle-injected rhGH are bioequivalent with respect to the amount absorbed. The criterion for bioequivalence is not met for the rate of absorption. It is unlikely that the latter finding will influence the pharmacodynamics of rhGH, since bioequipotency was established for the effect on IGF-I generation. Jet-injection was safe in use and was generally well tolerated.
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  • 20
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    Effects of cimetidine on pharmacokinetics and pharmacodynamics of losartan, an AT1-selective non-peptide angiotensin II receptor antagonist (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 115-119 
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    ISSN: 1432-1041
    Keywords: Losartan ; Cimetidine ; pharmacokinetics ; plasma renin activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract This was a 2-period randomized, crossover study in 8 healthy males to determine the effects of cimetidine (400 mg q.i.d. for 6 days) on the pharmacokinetics and pharmacodynamic effects of the angiotensin II receptor antagonist, losartan (100 mg). Cimetidine increased the AUC for losartan 18% without affecting the AUC for E-3174, the active metabolite of losartan. The increase in plasma renin activity following losartan was not affected by cimetidine (maximum mean increases 12.6 and 12.1 ng Ang I·ml−1·h−1 without and with cimetidine, respectively). These results indicate that cimetidine does not appear to alter the pharmacokinetics or pharmacodynamics of losartan to a clinically significant extent.
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    URL: http://dx.doi.org/10.1007/BF00192369
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  • 21
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    Lack of relationship between quinidine pharmacokinetics and the sparteine oxidation polymorphism (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 501-504 
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    ISSN: 1432-1041
    Keywords: Quinidine ; CYP2D6 ; Sparteine oxidation polymorphism ; (3S)-3OH-quinidine ; quinidine-N-oxide ; dihydroquinidine ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Quinidine is a very potent inhibitor of CYP2D6, but the role of the enzyme in the biotransformation of quinidine has only been investigated in a single in vitro study and in two small in vivo experiments, with contradictory results. The present investigation was designed to present definite evaluation of whether quinidine is metabolised by CYP2D6. Eight poor metabolizers (PM) and 8 extensive metabolizers (EM) of sparteine each took one oral dose of 200 mg quinidine. In the EM, the total clearance, the clearance via 3-hydroxylation and the clearance via N-oxidation, were 33, 3.7 and 0.23 l·h−1, respectively. In the PM, the corresponding values were 29, 3.1 and 0.18 l·h−1, respectively. There were no statistically significant differences between EM and PM in any of these pharmacokinetic parameters. It is concluded that CYP2D6 is not an important enzyme for the oxidation of quinidine.
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  • 22
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    Single-dose pharmacokinetics of nefazodone in healthy young and elderly subjects and in subjects with renal or hepatic impairment (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 221-228 
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    ISSN: 1432-1041
    Keywords: Nefazodone ; Geriatric assessment ; Hepatic cirrhosis ; Renal impairment ; pharmacokinetics ; antidepressive agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The single-dose pharmacokinetics of nefazodone (NEF) and its metabolites hydroxynefazodone (HO-NEF) and m-chlorophenylpiperazine (mCPP) were examined in 12 healthy younger subjects ≤55 years of age (YNG), 12 elderly subjects ≥65 years of age (ELD), 12 patients with biopsy proven hepatic cirrhosis (HEP) and 12 patients with moderate renal impairment (REN), ClCR 20–60 ml·min−1. The study was of parallel group design, with each of the four subject groups receiving escalating single oral doses of 50, 100 and 200 mg of nefazodone at 1 week intervals. Serial blood samples for pharmacokinetic analysis were collected for 48 h following each dose and plasma samples were assayed for NEF, HO-NEF and mCPP by a validated HPLC method. Single oral doses up to 200 mg of nefazodone were well tolerated by all subjects. Maximum plasma levels of NEF and HO-NEF were generally attained within 1 h after administration of nefazodone. HO-NEF and mCPP plasma levels were about 1/3 and 〈1/10 those of NEF, respectively. There were no apparent gender-related pharmacokinetic differences in any group of subjects. NEF and HO-NEF pharmacokinetics were dose dependent in all four subject groups; a superproportional increase in AUC and an increase in t1/2 with increasing dose was obtained, indicative of nonlinear pharmacokinetics. Relative to normal subjects, elderly and cirrhotic subjects exhibited increased systemic exposure to NEF and HO-NEF, as reflected by AUC, at all doses of nefazodone; subjects with moderate renal impairment did not. Elderly and cirrhotic patients may require lower doses of NEF to achieve and maintain therapeutic effectiveness.
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    URL: http://dx.doi.org/10.1007/BF00192383
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  • 23
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    Steady-state pharmacokinetics of nefazodone in subjects with normal and impaired renal function (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 229-235 
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    ISSN: 1432-1041
    Keywords: Nefazodone ; Renal impairment ; pharmacokinetics ; antidepressive agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The steady-state pharmacokinetics of nefazodone (NEF) and its metabolites hydroxynefazodone (HO-NEF) and m-chlorophenylpiperazine (mCPP) were compared in subjects with normal and impaired renal function. Patients: The Study was of parallel group design which included 7 subjects with normal (NOR) renal function, CLCR≥72 ml·min−1·1.73 m−2, 6 with moderate (MOD) renal impairment, CLCR 31–60 ml·min−1·1.73 m−2 and 9 with severe (SEV) renal impairment, CLCR≤30 ml·min−1·1.73 m−2. Subjects in each renal function group received a 100-mg oral dose of nefazodone hydrochloride BID for 7 days and a single morning dose on day 8. Starting 48 h after the last 100-mg dose, 200-mg doses were administered on a similar schedule to 3, 4 and 3 subjects from each renal function group (NOR, MOD and SEV, respectively). Single trough blood samples just prior to each morning dose (Cmin) and serial samples after the dose on day 8 were obtained at each dose level for pharmacokinetic analysis. Plasma samples were assayed by a specific HPLC method for NEF, HO-NEF and mCPP. The CMIN data indicated that steady state was attained by the third day of BID administration of both the 100- and 200-mg doses of nefazodone, regardless of degree of renal function. Both NEF and HO-NEF attained steady-state Cmax within 2 h after administration of nefazodone; tmax for mCPP was less defined and more delayed. HO-NEF and mCPP plasma levels were about 1/3 and 〈1/10 those of NEF, respectively, regardless of the status of renal function. Steady-state systemic exposure of NEF and HO-NEF, as reflected by AUC and Cmax, and elimination t1/2 values did not differ significantly among renal function groups. Conclusion: The study results suggest that dose adjustments may not be necessary, but nefazodone should be used with caution in the presence of severe renal impairment.
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  • 24
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    Relationship of changes in felodipine pharmacokinetics to haemodynamics during chronic oral treatment of congestive heart failure patients (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 203-210 
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    ISSN: 1432-1041
    Keywords: Felodipine ; pharmacokinetics ; haemodynamics ; congestive heart failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract In congestive heart failure patients the kinetics of felodipine, a dihydropyridine calcium antagonist, show interpatient differences after acute i.v. administration that disappear after 8 weeks oral treatment with a change in kinetics in the patients with the largest clearances (CL) and the smallest volumes of distribution (V SS). Pharmacokinetic and haemodynamic data were combined to construct a haemodynamic-pharmacokinetic model. This model shows that the differences between the patients in i.v. pharmacokinetics are consistent with a difference in plasma flow distribution between liver and poorly perfused tissues. In patients in whom kinetics changed, felodipine treatment is supposed to cause a redistribution of flow from liver to peripheral tissues, accompanied by a decreased work load of the heart and a larger increase in VO2max during therapy than in the other patients, whose workload increased. This suggests a better therapeutic response in the patients whose kinetics changed. As change in kinetics is related to felodipine CL and CL to liver plasma flow, felodipine CL or even indocyanine CL might be predictive for the therapeutic effect of felodipine.
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  • 25
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    The tolerability, pharmacokinetics and lack of effect on plasma cholesterol of 447C88, an AcylCoA:Cholesterol Acyl Transferase (ACAT) inhibitor with low bioavailability, in healthy volunteers (1995)
    Springer
    European journal of clinical pharmacology 49 (1995), S. 243-249 
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    ISSN: 1432-1041
    Keywords: Cholesterol acyltransferase ; Hypocholesterolaemic ; 447C88 ; volunteers ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract 447C88 (N-Heptyl-N′-(2,4 difluoro-4-6-(2(-4-(2,2 dimethylpropyl)phenyl)ethyl)phenyl)urea) is an inhibitor of human microsomal AcylCoA:Cholesterol acyltransferase (ACAT) with an IC50 of 10.2 ng·ml−1 (23 nM). It is poorly absorbed but 5 mg·kg−1·day−1 completely abolishes the rise in plasma cholesterol in cholesterol-fed rats. In this study, twelve healthy, male volunteers received single, oral doses of 25, 50, 100, 200, 400 and 800 mg of 447C88 (n+8) or placebo (n+4) with food in a double-blind study with at least a week between occasions. The 400 mg dose was repeated after an overnight fast. Subsequently, fourteen different volunteers received a single 200 mg dose of 447C88 (n+8) or placebo (n+6) with food and, a week later, the same dose twice daily for 10 days; all doses were given with food. All doses were well tolerated with no significant changes in vital signs, full blood counts or plasma biochemical profiles. Plasma concentrations of 447C88 were unquantifiable after the fasting dose and low after all other doses. Mean Cmax and AUC were 1.8 ng·ml−1 and 9.0 ng·ml−1·h after 200 mg rising to 5.4 ng·ml−1 and 23.8 ng·ml−1·h respectively after 800 mg; t1/2 was 1.3 to 5.2 h. After 10 days dosing, plasma 447C88 concentrations were higher in the evening than the morning probably due to administration of the evening dose with more food. There were no significant changes in plasma triglcerides or total, LDL- or HDL-cholesterol after dosing with 447C88.
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    Whole-blood pharmacokinetics and metabolic effects of the topical carbonic anhydrase inhibitor dorzolamide (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 453-460 
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    ISSN: 1432-1041
    Keywords: Dorzolamide ; Glaucoma ; carbonic anhydrase ; pharmacokinetics ; renal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Following a single-dose, open-label, pilot pharmacokinetic study in six subjects, the systemic pharmacokinetics and metabolic effects of dorzolamide after topical ocular administration were investigated in a double-blind, randomised, placebo-controlled study in 12 healthy volunteers. The subjects received a controlled diet on the 5 days before treatment initiation and throughout the study. For 14 days, a bilateral q.i.d. regimen of 3% dorzolamide, consisting of approximately 7.7 μg per day (21.3 μmol) dorzolamide hydrochloride, or placebo was given. Blood and urine electrolytes and acid-base profiles were measured 1 day prior to treatment and on days 1, 7 and 14 of treatment, and 24-h urine samples were collected daily. Topically applied dorzolamide was slowly taken up in erythrocytes and eliminated with a half life of approximately 120 days. Compared to the pre-study values, no significant treatment effect was observed in either the daily profiles or the 14-day cumulative sodium, potassium and citrate excretions. Two other volunteers given acetazolamide (125 mg q.i.d.) and assessed with the identical set of observations demonstrated marked metabolic changes. In spite of the prolonged and marked inhibition of carbonic anhydrase in red blood cells by dorzolamide, clinically significant metabolic and renal effects were not observed. The ocular tolerability profile was acceptable to all subjects.
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  • 27
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    Elimination of amrinone during continuous veno-venous haemofiltration after cardiac surgery (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 57-59 
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    ISSN: 1432-1041
    Keywords: Amrinone ; continuous veno-venous haemofiltration ; drug monitoring ; pharmacokinetics ; low cardiac output syndrom ; elimination ; renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract We studied the elimination of amrinone during continuous veno-venous haemofiltration (CVVHF) in three anuric patients after cardiac surgery. The patients had developed low cardiac output followed by acute prerenal failure. Plasma amrinone levels measured by HPLC were fitted to a two-compartment model. We found significant amrinone clearance, with a mean sieving coefficient (S) of 0.44%, which correlates with the protein-unbound, pharmacologically effective fraction of amrinone. The AUC of the arterial plasma concentration-time curve was decreased by 49.8%. All pharmacokinetic parameters showed wide interindividual variation. To ensure the therapeutic effect of amrinone and to avoid toxic adverse effects monitoring of plasma amrinone levels is necessary.
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    Paracetamol disposition in Thai patients during and after treatment of falciparum malaria (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 65-69 
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    ISSN: 1432-1041
    Keywords: Paracetamol ; Malaria ; pharmacokinetics ; phase II conjugation ; glucuronidation ; sulphation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Investigations in animals have suggested that conjugation of paracetamol may be reduced in malaria. We have measured plasma concentrations and the urinary excretion of paracetamol and its phase II metabolites in eight Thai patients during uncomplicated falciparum malaria and in convalescence, following a 1000 mg single oral dose. The apparent oral clearance (Malaria, 3.6; Convalescence, 3.9; ml·min−1·kg−1), the elimination half-life (Malaria, 3.8; Convalescence, 3.7 h) and apparent volume of distribution (Malaria, 1.2; Convalescence, 1.2; l·kg−1) of paracetamol were similar during malaria and convalescence. In addition, the urinary excretion of paracetamol and its major phase II metabolites and their formation clearances from paracetamol were not significantly different between the two study phases. These data show that clinical malaria infection has no effect on the conjugation of paracetamol in man.
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  • 29
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    The acetylation phenotype: does it contribute to the non-linearity of the metabolite pharmacokinetics of metamizol? (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 79-80 
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    ISSN: 1432-1041
    Keywords: Metamizol ; Acetylation phenotype ; metabolites ; pharmacokinetics ; dose-linearity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202178
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    Relative bioavailability of nicotine from a nasal spray in infectious rhinitis and after use of a topical decongestant (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 71-75 
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    ISSN: 1432-1041
    Keywords: Nicotine ; Rhinitis ; pharmacokinetics ; nasal spray ; xylometazoline ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The relative bioavailability of nicotine from a nasal spray was assessed in 15 smokers suffering a common cold and rhinitis according to generally accepted criteria. The patients were given a single dose of 2 mg nicotine from the nasal spray with and without concurrent administration of a nasal vasoconstrictor decongestant, xylometazoline, in randomised order. Control session measurements were made in the disease-free state. Applying strict bioequivalence criteria, we found that common cold/rhinitis slightly reduced the bioavailability of nicotine, both in its rate and extent; the geometric mean of the ratio of Cmax, AUC and tmax were 0.81, 0.93 and 1.36, respectively. The nasal vasoconstrictor, xylometazoline, normalised the extent of the bioavailability of nicotine, but further prolonged the time for absorption to almost twice that measured in the disease-free state, increasing the tmax ratio to 1.72. The results suggest that a minor proportion of people stopping smoking with the help of a nicotine nasal spray may experience a minor reduction in the effect of the spray during common cold/rhinitis. However, the nicotine self-titration behaviour found with most smoking cessation products (except the nicotine patch) will automatically lead to an adjustment of the dosage to achieve the desired effect.
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    Effects of liver disease on the pharmacokinetics of intravenous and oral chlordesmethyldiazepam (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 265-268 
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    ISSN: 1432-1041
    Keywords: Chlordesmethyldiazepam ; Liver disease ; pharmacokinetics ; i.v./p.o. administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract We studied the pharmacokinetics of a single 0.5-mg i.v. dose of chlordesmethyldiazepam in 8 patients with liver disease and in 12 age-matched healthy controls. The kinetics were also studied of a single 1-mg oral dose in the patients with liver disease. After i.v. administration the kinetics of total chlordesmethyldiazepam in patients with liver disease differed from those in controls: elimination half-life was almost twice that in controls (395 and 204 h), as a consequence of a marked reduction in total clearance (0.13 and 0.25 ng·ml−1·h−1), whereas the apparent volume of distribution was similar in patients and controls (4.7 and 3.9 1/kg−1). The free fraction of the drug in patients was higher (5.5%) than in controls (2.9%). Correction for differences in protein binding revealed clearance in the patients was one-fifth (1.8 and 10.5 ng ml−1·kg−1) and volume of distribution one-half (65.0 and 118.4 1·kg−1) that in controls. The systemic availability of oral chlordesmethyldiazepam was high (110%) in spite of a relatively slow absorption rate. These results indicate a need for caution in the administration of chlordesmethyldiazepam to patients with liver disease.
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    Effects of a finnish sauna on the pharmacokinetics and haemodynamic actions of propranolol and captopril in healthy volunteers (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 133-137 
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    ISSN: 1432-1041
    Keywords: Sauna ; Propranolol ; Captopril ; pharmacokinetics ; blood pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The effects of a Finnish sauna on propranolol pharmacokinetics and on the pharmacodynamics of propranolol and captopril were studied in healthy, young volunteers (2 males, 6 females) in a double-blind, cross-over trial. The subjects received single oral doses of placebo. propranolol (40 mg) or captopril (12.5 mg) in sauna and control sessions at a one-week interval. The sauna sessions consisted of three repetitive 10-min stays in a sauna (85–100°C, relative humidity 25–35%) separated by two 5-min rest periods in a cool room. Sauna bathing started 35, 50 and 65 min after ingestion of the drugs. Venous blood for plasma propranolol measurement were collected before and 15, 30, 45, 60, 75, 90 min and 2, 3, 4, 5, 7 and 24 h after drug intake. The sauna significantly increased the maximum concentration (Cmax 41 vs. 28 ng·ml−1) of propranolol and the mean plasma propranolol concentration 60 and 90 min, and 2 and 3 h after drug administration. It also significantly increased the AUC0–5h (119 vs 71 μg·h·l-1) of propranolol from 0 to 5 hours tmax, t1/2β and AUC0–24h of propranolol did not differ between the control and sauna sessions. The higher propranolol levels during and after the cessation of sauna bathing did not lead to significant changes in blood pressure or heart rate compared to the control period. Captopril had no major effects on these parameters during the post-sauna phase. The results suggest that a sauna may increase the plasma propranolol concentration, but that did not notably affect the blood pressure or heart rate in healthy, young volunteers during the post-sauna phase.
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    Pharmacokinetic interactions of alcohol and acetylsalicylic acid (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 151-153 
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    ISSN: 1432-1041
    Keywords: Ethanol ; Acetylsalicylic acid ; ibuprofen ; paracetamol ; non-steroidal anti-inflammatory drugs ; interactions ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract This study assessed the influence of acetylsalicylic acid (ASA, 1.0 g), ibuprofen (0.8 g) and paracetamol (1.0 g) on the single-dose kinetics of ethanol in 12 healthy volunteers ingesting the drug and a standardised 1840-kJ breakfast 1 h before intake of ethanol. It also assessed the influence of ethanol on the single-dose kinetics of 1.0 g ASA in ten fasting healthy volunteers. Plasma concentrations of ethanol were measured by gas chromatography, and those of the drugs by liquid chromatography. There was no effect of ASA, ibuprofen or paracetamol on the single-dose kinetics of ethanol, but concurrent intake of ethanol reduced the peak concentration of ASA by 25%.
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    Influence of piroxicam coadministration on pharmacodynamic parameters and the plasma concentration/effect relationship of recombinant hirudin (CGP 39393) (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 241-246 
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    ISSN: 1432-1041
    Keywords: Recombinat hirudin ; Piroxicam ; activated partial thromboplastin time ; pharmacokinetics ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Recombinant hirudins are currently under investigation for use in myocardial infarction and unstable angina. In this study the influence of piroxicam on the pharmacodynamics and pharmacokinetics of a recombinant hirudin preparation (CGP 39393) administered intravenously was determined. Twelve healthy, male volunteers received piroxicam 10 mg and matching placebo once daily for 12 days according to a double-blind, randomised cross-over design. On the 12th day, the dose of piroxicam was followed by a 6-hour infusion of hirudin 0.1 mg·kg−1·h−1. Plasma concentrations and urinary excretion of hirudin and repeated measurements of the activated partial thromboplastin time (APTT), bleeding time and platelet adhesion index were assessed up to 24 h after the start of the infusion. The maximum APTT was 83 s (placebo) and 84 s (piroxicam), 3 to 4 h after the start of the infusion, and was comparable on both study days. The AUD0–24 (APTT) came to 913 s·h·kg−1 under placebo and it was slightly increased to 1,017 s·h·kg−1 after piroxicam; the 95%-confidence interval according to MOSES ranged from 0.97 to 1.24, and the point estimator was 1.10. Bleeding time was significantly prolonged from 290 s under placebo to 345 s under piroxicam before the start of the infusion of hirudin. No further prolongation was found during or after the infusion. No change was observed in the platelet adhesion index. Responsiveness parameters according to a sigmoidal Emax-model were obtained from the hirudin-plasma concentration/effect (i.e. APTT-prolongation)-curves after placebo and piroxicam. Maximal APTT-prolongation (Emax; i.e. peak APTT minus the baseline value) was 53 s after placebo and 52 s after piroxicam. The EC50 was 34 nmol·l−1 after placebo and 40 nmol·h·l−1 after piroxicam. The AUC0 of hirudin was to 539 nmol·h·l−1·kg−1 under placebo and 557 nmol·h·l−1·kg−1 after piroxicam coadministration; the 95%- confidence interval according to MOSES ranged from 0.95 to 1.14, and the point estimator was 1.03. No period effect was detected. There were no significant differences between the other pharmacokinetic parameters except Vss, which was increased slightly from 0.23 l to 0.27 l under piroxicam. The results do not show a clinically relevant pharmacodynamic and/or pharmacokinetic interaction between hirudin and piroxicam.
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    Pharmacokinetics of fluconazole after oral administration in children with human immunodeficiency virus infection (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 291-293 
    Details
    ISSN: 1432-1041
    Keywords: Fluconazole ; absorption ; pharmacokinetics ; HIV infection ; children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The objective of this study was to determine the pharmacokinetics of fluconazole after oral administration in children with human immunodeficiency virus (HIV) infection. After an overnight fast, a single dose of either 2 mg·kg−1 or 8 mg·kg−1 was administered in a suspension; five children received 2 mg·kg−1 and four 8 mg·kg−1 (ages 5–13 years). Blood samples were collected at various times on day 1, and once daily on days 2–7 after the dose. Fluconazole serum concentrations were measured by gas chromatography. At the dose of 2 mg·kg−1, the Cmax, AUC (0–∞), and t1/2 ranged from 2.3–4.4 μg·ml−1, 84.9–136 μg·h·ml−1, and 19.8–34.8 h, respectively. At the dose of 8 mg·kg−1 the Cmax, AUC (0–∞), and t1/2 ranged from 5.4–12.1 μg·ml−1, 330–684 μgh·ml−1, and 25.6–42.3 h, respectively. When compared with published data in healthy adults, fluconazole achieved similar serum concentrations in the present group of children, indicating a nearly complete degree of absorption.
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    URL: http://dx.doi.org/10.1007/BF00198314
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    Humoral and haemodynamic effects of idrapril calcium, the prototype of a new class of ACE-inhibitors, in essential hypertensive patients (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 339-343 
    Details
    ISSN: 1432-1041
    Keywords: Idrapril ; ACE-inhibition ; Hypertension ; essential ; active renin ; angiotensin II ; blood pressure ; pharmacodynamics ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Idrapril is the prototype of a new class of ACE inhibitors, characterised by the presence of a hydroxdmic group. Six untreated in-patients with essential hypertension were given single oral doses of the calcium salt of idrapril, idrapril calcium (200 mg) and placebo according to a double blind, randomised experimental design. Supine and upright blood pressure, heart rate, plasma idrapril serum ACE, active renin and angiotensin II were measured at timed intervals for 24 hours after dosing. Plasma idrapril reached a peak after 2 hours (3.01 μ·ml−1), and by 12 hours the compound had al most disappeared (67 ng·ml−1). Derived t1/2 was 1.4–2.2 h. ACE activity was suppressed [from 77.9 to 3.3 after 2 hours and 11.8 after 12 hours nmol−1·min−1·ml] and angiotensin II production inhibited [from 8.8 to 3.1 (after 1 hour) and 7.5 (after 12 hours) pg·ml−1] for up to 12 h, while active renin rose up to 24 h [from 12.3 to 20.1 (after 8 hours) and 17.5 (after 24 hours) pg·ml−1]. Compared to placebo, idrapril calcium significantly lowered both supine blood pressure starting at 4 hours (idrapril calcium 140/93 mmHg; placebo 157/101 mmHg) up to 24 hours (idrapril calcium 142/91 mmHg; placebo: 155/97 mmHg), and upright blood pressure starting at 3 hours (idrapril calcium 135/95 mmHg; placebo 147/100 mmHg) up to 24 hours (idrapril calcium 132/92 mmHg; placebo 145/100 mmHg). Idrapril calcium appears to be an effective ACE inhibitor in essential hypertension, with a hypotensive action for up to 24 h.
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    Relative bioavailability of cyclosporin from conventional and microemulsion formulations in heart-lung transplant candidates with cystic fibrosis (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 285-289 
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    ISSN: 1432-1041
    Keywords: Cyclosporin ; Cystic fibrosis ; pharmacokinetics ; bioavailability ; formulation ; transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Patients with cystic fibrosis absorb cyclosporin poorly and erratically. We have compared the relative bioavailability of cyclosporin from conventional and microemulsion formulations in 5 adult heart-lung transplant candidates with cystic fibrosis. Relative bioavailability was compared at two dose levels (200 mg and 800 mg). A randomized 4-period cross-over study was performed with at least a 7 days washout period between each single dose pharmacokinetic study. Blood cyclosporin concentrations were measured by a selective monoclonal antibody-based radioimmunoassay. The bioavailability of cyclosporin from the microemulsion formulation was 1.84 (95% C.I. 1.05 to 3.22; P−0.04) and 2.09 (95% C.I. 0.95 to 4.61; P−0.06) times higher compared with the conventional formulation at 200 mg and 800 mg respectively. Cmax following the microemulsion formulation was 3.38 (C.I. 1.14 to 10.59; P−0.04) and 2.77 (C.I. 1.48 to 5.19; P−0.01) times higher compared with the conventional formulation at 200 mg and 800 mg respectively. The higher Cmax following the microemulsion formulation was accompanied by shorter tmax. An enhancement of cyclosporin absorption with the microemulsion formulation was demonstrated in each patient for at least one dose level. We conclude that rate and extent of cyclosporin absorption from the microemulsion formulation is greater compared with the conventional formulation in patients with cystic fibrosis. The potential therapeutic and economic benefits of the micro-emulsion formulation should be evaluated in cystic fibrosis patients following heart-lung transplantation.
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    URL: http://dx.doi.org/10.1007/BF00198313
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    Pharmacokinetic-pharmacodynamic (PK-PD) modeling for a new antihypertensive agent (neutral metalloendopeptidase inhibitor SCH 42354) in patients with mild to moderate hypertension (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 351-359 
    Details
    ISSN: 1432-1041
    Keywords: Atrial natriuretic peptide ; Hypertension ; SCH 42354 ; blood pressure ; neutral metalloendopeptidase ; pharmacodynamics ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract SCH 42354, a neutral metalloendopeptidase (NEP) inhibitor, is the pharmacologically active form of the prodrug SCH 42495. It exerts antihypertensive effects by potentiating atrial natriuretic peptide (ANP) activity through inhibition of its hydrolysis by NEP. The objective of this study was to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of SCH 42354 in hypertensive males. SCH 42495 12.5 to 400 mg was administered orally to hypertensive men twice daily in a double-blind, placebo controlled multiple-dose parallel group design. Plasma SCH 42354 concentration and diastolic blood pressure (DBP) data were used to develop a PK-PD model using two approaches. In the first (non-integrated) approach, the “link” model was used to predict effect-site concentrations, and was applied to data obtained at the 300 and 400 mg BID doses only; data at the other (lower) doses were not amenable to modeling because of high variability. Effect-site concentration and DBP data were then fit to a sigmoid Emax PD model. For the 300 mg BID dose, PD parameters were: maximum effect (Emax), 8.1mmHg; no-drug effect (Eo), 3.6 mmHg; concentration corresponding to 50% of maximum response (EC50), 0.87 μg·ml−1; and gamma, 3.9. In the second (time-integrated) approach, plasma SCH 42354 concentration and effect data obtained over the entire dose range were integrated with respect to time. Average plasma concentration and DBP data were then fit to a simple Emax PD model. PD parameters obtained over the dose range were: Emax, 10.3 mmHg; Eo, 2.0 mmHg; and EC50, 0.7 μg·ml−1. These were similar to the estimates obtained from the first approach, demonstrating that the integrated (average) data allow PK-PD modeling over the (entire) dose range. The analysis showed that, at steady-state, a 400 mg BID dose of SCH 42495 produced an approximate 10 mmHg decrease in DBP in hypertensive males; the average plasma SCH 42354 concentration attained at this dose was approximately 1.8 μg·ml−1.
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    The effect of pH on the buccal and sublingual absorption of captopril (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 373-379 
    Details
    ISSN: 1432-1041
    Keywords: Captopril ; sublingual ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of pH on the buccal and sublingual absorption of captopril was evaluated using in vitro techniques and human studies. Partitioning of captopril into n-octanol was lowest over the pH range 5 to 8 and highest at pH values 3, 4 and 9. Using the buccal absorption technique, the partitioning of captopril (2 mg) was examined in six healthy male volunteers from buffered solutions (pH 3, 4, 5, 6, 7, 8, and 9). Lowest buccal partitioning occurred at pH 3 while maximal buccal partitioning occurred at pH 7. These data clearly indicated that the buccal absorption of captopril did not obey the classical pH/partition hypothesis suggesting that mechanisms other than passive diffusion were involved in its absorption. Captopril pharmacokinetic and pharmacodynamic parameters were determined after administration of buffered sublingual captopril (pH 7, optimal pH for absorption as determined from the buccal partitioning data) and unbuffered sublingual captopril. The study was performed in eight healthy volunteers in a randomised single-blind cross-over fashion. The tmax for captopril was found to be approximately 11 minutes earlier after buffered versus unbuffered sublingual administration and AUC0–30 min increased by approximately 30% in the case of buffered captopril. Cpmax, AUC0–180 min and relative bioavailability did not differ between the buffered and unbuffered administration. Pharmacodynamic parameters (BP, heart rate and plasma renin activity) did not differ significantly between buffered and unbuffered sublingual administration. The increased rate of captopril absorption after buffered sublingual administration was small and is likely to offer little therapeutic advantage over conventional sublingual formulation.
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    Plasma and red blood cell pharmacokinetics of pimobendan enantiomers in healthy Chinese (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 537-542 
    Details
    ISSN: 1432-1041
    Keywords: Pimobendan ; enantiomers ; pharmacokinetics ; stereoselectivity ; demethyl pimobendan ; metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The pharmacokinetics of enantiomers of pimobendan and their demethylated metabolites in plasma and red cells were studied in 8 normal healthy volunteers. After racemic pimobendan 5 mg IV, the plasma concentration-time curve followed a two-compartment open-model with elimination half-lives of 1.81 h and 1.86 h for (+)- and (−)-pimobendan, respectively. The clearances and volumes of distribution postequilibrium were 13.5 ml · min−1 · kg−1, 14.4 ml · min−1 · kg−1; 1.74 l · kg−1 and 2.34 l · kg−1 for (+)- and (−)-pimobendan, respectively. Plasma protein binding (n=3) of (+)-, (−)-pimobendan, (+)- and (−)-demethylated metabolites was 97.6, 97.6, 92.2 and 92.5%, respectively. The plasma concentration-time curve also followed a two-compartment open model after oral administration of 7.5 mg racemic pimobendan. The absolute bioavailabilities of (+)- and (−)-pimobendan were 0.51 and 0.55. Peak levels of (+)-and (−)-pimobendan, both at 1.2 h, were 15.8 and 16.8 ng · ml−1, respectively. The (+)- and (−)-pimobendan concentrations in red cells were determined and their pharmacokinetics were estimated using red blood cell data. Interesting phenomena were observed: the peak concentrations of (+)- and (−)-pimobendan in red blood cells were about 5.5- and 9.2-times higher than in plasma, and the AUCs were correspondingly elevated. The volume of distribution of the central compartment of (−)-pimobendan in red cell was significantly smaller than that of (+)-pimobendan. (0.24 vs. 0.42 l · kg−1.) Similar phenomena were found after IV administration. These all indicated stereoselective partitioning or distribution of (−)-pimobendan into red cells. Since the elimination half-life of (+)- and (−)-pimobendan in red cells was similar (3.07 vs 2.97 h), the highly significant difference in clearance between (+)- and (−)-pimobendan (3.7 vs 2.3 ml · min−1 · kg−1) was solely due to the stereoselective distribution of (−)-pimobendan into the red blood cells. This stereoselective property of the (−)-isomer may be the explanation of a previous report that (−)-pimobendan produced a 1.5-times larger contractile force in detergent-skinned preparations of cardiac muscle from guinea pig and dog than the (+)-isomer.
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    MBOHO calculations of phosphorus-carbon nuclear spin-spin coupling constants (1995)
    Springer
    Theoretical chemistry accounts 92 (1995), S. 61-65 
    Details
    ISSN: 1432-2234
    Keywords: NMR ; Nuclear spin coupling constant ; Maximum bond order hybrid orbital ; Phosphorus-carbon coupling ; Net atomic charge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The novel generalized correlation of the nuclear spin-spin coupling constants with the atomic hybrids and net charges is employed to give a new relationship for calculating the directly bonded phosphorus-carbon coupling constants by use of the maximum bond order hybrid orbital procedure together with the extended Hückel molecular orbital calculation. The calculated coupling constants of phosphorus-carbon are all in good agreement with the experimental data, which shows that the new relationship obtained in the present paper is quite satisfactory for calculation of the phosphorus-carbon coupling constants.
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    URL: http://dx.doi.org/10.1007/BF01134204
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    Determination of the structure of fusaproliferin by1H-NMR and distance geometry (1995)
    Springer
    Structural chemistry 6 (1995), S. 183-189 
    Details
    ISSN: 1572-9001
    Keywords: NMR ; distance geometry ; cluster analysis ; absolute configuration ; fusaproliferin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The absolute configuration of fusaproliferin, a toxic metabolite produced byFusarium proliferation, was determined by the combined use of1H NMR and distance geometry. The configuration of double bonds has been determined in agreement with NOESY buildup data. An R configuration for C10 was determined using Mosher's method. Processing the constraints obtained from NOESY experiments with a distance geometry program, a limited number (80) of possible structures was derived. An agglomerative nonhierarchical method of clustering was used in order to place these structures into classes suggested by the data, and not previously defined in any way. This statistical method showed that indeed the structures could be grouped in four classes. One of these classes is represented by a single structure, with the highest sum of violations and was discarded. All other structures have the same chirality; respectively S for C14 and R for C15. In solution the overall conformation is quite well defined in the region of the five-member ring and the planes of double bonds C2–C3 and C11–C12, while near to C8 and C9 internal flexibility appears evident.
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    Ascorbic acid prevents lipid peroxidation and oxidative damage of proteins in guinea pig extrahepatic tissue microsomes (1995)
    Springer
    Molecular and cellular biochemistry 142 (1995), S. 71-78 
    Details
    ISSN: 1573-4919
    Keywords: ascorbic acid ; microsomes ; NADPH ; superoxide radical ; lipid peroxidation ; oxidative damage of proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It has recently been indicated that in the absence of free iron, NADPH initiates oxidative damage of proteins in guinea pig liver microsomes and also lipid peroxidation and protein damage in cardiac microsomes and that ascorbic acid specifically inhibits both the lipid peroxidation and protein damage [Mukhopadhyay CK, Chatterjee IB: J Biol Chem 269: 13390–13397, 1994; Mukhopadhyay Met al.: Mol Cell Biochem 126: 69–75, 1993]. In this paper we demonstrate that Fe(III)-independent NADPH-initiated lipid peroxidation and oxidative damage of proteins occur in the microsomes of all the extrahepatic tissues including lung, kidney, adrenal gland and brain and that both the lipid peroxidation and protein damage are specifically prevented by ascorbic acid. We further demonstrate that when NADPH is replaced by $$O_2^{\bar \cdot } $$ as the electron donor, the $$O_2^{\bar \cdot } $$ lipid peroxidation and protein damage are also inhibited by ascorbic acid.
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    Modulation of cyclophosphamide-induced early lung injury by curcumin, an anti-inflammatory antioxidant (1995)
    Springer
    Molecular and cellular biochemistry 142 (1995), S. 79-87 
    Details
    ISSN: 1573-4919
    Keywords: cyclophosphamide ; curcumin ; bronchoalveolar lavage fluid ; lavage cells ; lipid peroxidation ; antioxidant defense mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Cyclophosphamide causes lung injury in rats through its ability to generate free radicals with subsequent endothelial and epithelial cell damage. In order to observe the protective effects of a potent anti-inflammatory antioxidant, curcumin (diferuloyl methane) on cyclophosphamide-induced early lung injury, healthy pathogen free male Wistar rats were exposed to 20 mg/100 g body weight of cyclophosphamide, intraperitoneally as a single injection. Prior to cyclophosphamide intoxication oral administration of curcumin was performed daily for 7 days. At various time intervals (2, 3, 5 and 7 days post insult) serum and lung samples were analyzed for angiotensin converting enzyme, lipid peroxidation, reduced glutathione and ascorbic acid. Bronchoalveolar lavage fluid was analyzed for biochemical constituents. The lavage cells were examined for lipid peroxidation and glutathione content. Excised lungs were analyzed for antioxidant enzyme levels. Biochemical analyses revealed time course increases in lavage fluid total protein, albumin, angiotensin converting enzyme (ACE), lactate dehydrogenase, N-acetyl-β-D-glucosaminidase, alkaline phosphatase, acid phosphatase, lipid peroxide levels and decreased levels of glutathione (GSH) and ascorbic acid 2, 3, 5 and 7 days after cyclophosphamide intoxication. Increased levels of lipid peroxidation and decreased levels of glutathione and ascorbic acid were seen in serum, lung tissue and lavage cells of cyclophosphamide groups. Serum angiotensin converting enzyme activity increased which coincided with the decrease in lung tissue levels. Activities of antioxidant enzymes were reduced with time in the lungs of cyclophosphamide groups. However, a significant reduction in lavage fluid biochemical constituents, lipid peroxidation products in serum, lung and lavage cells with concomitant increase in antioxidant defense mechanisms occurred in curcumin fed cyclophosphamide rats. Therefore, our results suggest that curcumin is effective in moderating the cyclophosphamide induced early lung injury and the oxidant-antioxidant imbalance was partly abolished by restoring the glutathione (GSH) with decreased levels of lipid peroxidation.
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    Cisplatin induced nephrotoxicity and the modulating effect of glutathione ester (1995)
    Springer
    Molecular and cellular biochemistry 144 (1995), S. 7-11 
    Details
    ISSN: 1573-4919
    Keywords: cisplatin ; glutathione ester ; reduced glutathione ; antioxidants ; lipid peroxidation ; nephrotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The objective of this study was to assess the therapeutic advantage of glutathione ester along with cisplatin. Comparisons were made with renal reduced glutathione, enzymatic antioxidants, and lipid peroxidation levels. Cisplatin caused differential toxic effects on renal antioxidants and lipid peroxidation. However administration of glutathione ester modulates the toxic effects of cisplatin observed in renal antioxidants and lipid peroxidation. The finding that glutathione ester co-administration along with cisplatin is more effective and advantageous in protecting against the nephrotoxicity of cisplatin when it was given alone.
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    URL: http://dx.doi.org/10.1007/BF00926734
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    Effects of magnesium and iron on lipid peroxidation in cultured hepatocytes (1995)
    Springer
    Molecular and cellular biochemistry 144 (1995), S. 141-145 
    Details
    ISSN: 1573-4919
    Keywords: magnesium ; iron ; lipid peroxidation ; hepatocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In primary cultures of rat hepatocytes, the effects of extracellular Mg2+ and Fe on lipid peroxidation (LPO) as measured by means of malondialdehyde (MDA) formation were investigated. Incubation of hepatocytes at decreasing extracellular Mg2+ concentration enhanced LPO, depending on extracellular Fe. About 96% of MDA accumulated in the culture medium. Addition of desferrioxamine prevented LPO. Additionally, the formation of oxygen free radicals was determined by fluorescence reduction of cis-parinaric acid. With this method, an immediate decay of fluorescence was found after addition of Fe2+. Fluorescence reduction was completely prevented by desferrioxamine, indicating the function of extracellular Fe. This mechanism may operate additionally to the increase in intracellular Fe and intracellular formation of oxygen free radicals during Mg deficiencyin vivo.
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    Inhibition of cardiac sarcolemma Na+−K+ ATPase by oxyradical generating systems (1995)
    Springer
    Molecular and cellular biochemistry 147 (1995), S. 139-144 
    Details
    ISSN: 1573-4919
    Keywords: sarcolemmal Na+−K+ ATPase ; lipid peroxidation ; oxyradicals ; cardiac membrane ; oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The Na+−K+ ATPase activity and SH group content were decreased whereas malondialdehyde (MDA) content was increased upon treating the porcine cardiac sarcolemma with xanthine plus xanthine oxidase, which is known to generate superoxide and other oxyradicals. Superoxide dismutase either alone or in combination with catalase and mannitol fully prevented changes in SH group content but the xanthine plus xanthine oxidase-induced depression in Na+−K+ ATPase activity as well as increase in MDA content were prevented partially. The Lineweaver-Burk plot analysis of the data for Na+−K+ ATPase activity in the presence of different concentrations of MgATP or Na+ revealed that the xanthine plus xanthine oxidase-induced depression in the enzyme activity was associated with a decrease in Vmax and an increase in Km for MgATP; however, Ka value for Na+ was decreased. Treatment of sarcolemma with H2O2 plus Fe2+, an hydroxyl and other radical generating system, increased MDA content but decreased both Na+−K+ ATPase activity and SH group content; mannitol alone or in combination with catalase prevented changes in SH group content fully but the depression in Na+−K+ ATPase activity and increase in MDA content were prevented partially. The depression in the enzyme activity by H2O2 plus Fe2+ was associated with a decrease in Vmax and an increase in Km for MgATP. These results indicate that the depressant effect of xanthine plus xanthine oxidase on sarcolemmal Na+−K+ ATPase may be due to the formation of superoxide, hydroxyl and other radicals. Furthermore, the oxyradical-induced depression in Na+−K+ ATPase activity may be due to a decrease in the affinity of substrate in the sarcolemmal membrane.
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    Characteristics of Fe(II)ATP complex-induced damage to the rat liver mitochondrial membrane (1995)
    Springer
    Molecular and cellular biochemistry 145 (1995), S. 53-60 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; oxidative stress ; iron ; lipid peroxidation ; membrane permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It is well established that several iron complexes can induce oxidative damage in hepatic mitochondrial membranes by catalyzing the formation of ·OH radicals and/or by promoting lipid peroxidation. This is a relevant process for the molecular basis of iron overload diseases. The present work demonstrates that Fe(II)ATP complexes (5–50μM) promote an oxygen consumption burst in a suspension of isolated rat liver mitochondria (either in the absence or presence of Antimycin A), caused mainly by lipid peroxidation. Fe(II)ATP alone induced small levels of oxygen uptake but no burst. The time course of Fe(II)ATP oxidation to Fe(III)ATP in the extramitochondrial media also reveals a simultaneous ‘burst phase’. The iron chelator Desferal (DFO) or the chain-break antioxidant butylated hydroxytoluene (BHT) fully prevented both lipid peroxidation (quantified as oxygen uptake burst) and mitochondrial swelling. DFO and BHT were capable of stopping the ongoing process of peroxidation at any point of their addition to the mitochondrial suspension. Conversely, DFO and BHT only halted the Fe(II)ATP-induced mitochondrial swelling at the onset of the process. Fe(II)ATP could also cause the collapse of mitochondrial potential, which was protected by BHT if added at the onset of the damaging process. These results, as well as correlation studies between peroxidation and mitochondrial swelling, suggest that a two phase process is occurring during Fe(II)ATP-induced mitochondrial damage: one dependent and another independent of lipid peroxidation. The involvement of lipid peroxidation in the overall process of mitochondrial membrane injury is discussed.
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    URL: http://dx.doi.org/10.1007/BF00925713
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    Relationship between elevated lipid peroxides, vitamin E deficiency and hypertension in preeclampsia (1995)
    Springer
    Molecular and cellular biochemistry 151 (1995), S. 33-38 
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    ISSN: 1573-4919
    Keywords: preeclampsia ; vitamin E ; lipid peroxidation ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Preeclampsia or pregnancy-induced hypertension is a major cause of both maternal and fetal-neonatal morbidity and mortality. The deficiency of vitamin E can cause accumulation of lipid peroxidation products, which, in turn, can induce vasoconstriction. This study has examined any evidence of increased cellular lipid peroxidation and accumulation of malonydialdehyde (MDA, an end product of lipid peroxidation) in pregnancy-induced hypertension and any relationship between the elevated MDA and lower vitamin E levels with hypertension in pregnant women. EDTA-Blood was collected from pregnant women at the time of delivery. Plasma vitamin E was determined by HPLC; MDA by the thiobarbituric acid-reactivity. Subjects with diastolic blood pressure(DBP) ≥90 mm Hg were considered hypertensive (HT) and with 〈90 mm Hg normotensive (NT). Data (Mean±SE) from 49 NT and 11 HT women show that HT has significantly lower vitamin E (22±1 vs 27±1 nmole/ml, p〈0.03) and elevated MDA levels (0.56±0.06 vs 0.43±0.02 nmole/ml, p〈0.03) compared to NT; the ages and gestational ages of women were similar. Among all women, there was a significant positive relationship between DBP and MDA levels (r=0.27, p〈0.05), and a significant negative relationship between vitamin E levels and DBP (−0.36, p〈0.005), and a significant negative relationship between MDA and vitamin E levels (r=−0.27, p〈0.05). Thus, HT women's plasma has significantly lower E and higher MDA levels, and DBP significantly correlates with the extent of vitamin E deficiency and increased MDA levels. This study suggests a relationship between elevated lipid peroxidation and lower vitamin E levels and hypertension in pregnancy (preeclampsia).
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    URL: http://dx.doi.org/10.1007/BF01076893
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    Oxidative stress and heart failure (1995)
    Springer
    Molecular and cellular biochemistry 147 (1995), S. 77-81 
    Details
    ISSN: 1573-4919
    Keywords: antioxidants ; redox state ; lipid peroxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Various abnormalities have been implicated in the transition of hypertrophy to heart failure but the exact mechanism is still unknown. Thus heart failure subsequent to hypertrophy remains a major clinical problem. Recently, oxidative stress has been suggested to play a critical role in the pathogenesis of heart failure. Here we describe antioxidant changes as well as their significance during hypertrophy and heart failure stages. Heart hypertrophy in rats and guinea pigs, in response to pressure over-load, is associated with an increase in ‘antioxidant reserve’ and a decrease in oxidative stress. Hypertrophied rat hearts show increased tolerance for different oxidative stress conditions such as those imposed by free radicals, hypoxia-reoxygenation and ischemia-reperfusion. On the other hand, heart failure under acute as well as chronic conditions is associated with reduced antioxidant reserve and increased oxidative stress. The latter may have a causal role as suggested by the protection seen with antioxidant treatment in acute as well as in chronic heart failure. It is becoming increasingly apparent that, anytime the available antioxidant reserve in the cell becomes inadequate, myocardial dysfunction is imminent.
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    Lipid peroxidation of erythrocytes during anemia of the hamsters infected withLeishmania donovani (1995)
    Springer
    Molecular and cellular biochemistry 146 (1995), S. 99-105 
    Details
    ISSN: 1573-4919
    Keywords: antioxidant reserve ; membrane cholesterol/phospholipid ratio ; lipid peroxidation ; erythrocytes ; Leishmani donovani
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Visceral leishmaniasis has been found to be associated with severe anemia and premature lysis of erythrocytes. Peroxidative damage of red cells has been noted in several hemolytic anemias. Present study shows enhanced formation of methemoglobin in hamsters infected withLeishmania donovani. Increased formation of malonyldialdehyde and diene conjugate has been noted in the erythrocytes of the infected animals with the progress of anemia. Results showed decreased activities of protective enzymes like superoxide dismutase, catalase and glutathione reductase against peroxidative attack. An increase in the membrane cholesterol/phospholipid ratio and a decrease in membrane fluidity of erythrocytes were observed under the diseased condition. Densitometric scan after SDS-PAGE of red cell membrane of the infected animals revealed significant degradation of band 3 and band 4.1 proteins. The results suggest that alteration in the membrane may lead to reduced life span of the red cells in experimental visceral leishmaniasis.
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    Modulations in antioxidant enzymes in different tissues of marine bivalvePerna viridis during heavy metal exposure (1995)
    Springer
    Molecular and cellular biochemistry 146 (1995), S. 107-113 
    Details
    ISSN: 1573-4919
    Keywords: Marine mussels ; metal accumulation ; lipid peroxidation ; antioxidant enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Lipid peroxidation induced by metals at sub-lethal levels, alter physiological and biochemical characteristics of biological systems. To counter the detrimental effects of the prooxidant activity of metals, a group of antioxidant enzyme systems function in the organisms. The present study was performed to investigate into the lipid peroxidation product formation due to the exposure to effects of the metals namely aluminium, lead and cadmium at sub-lethal concentrations and the biological response through protective antioxidant enzyme activity in the marine mussels,Perna viridis Lin. This organism is a known bioindicator and bioconcentrator of metals in the environment. The results of the present study were: (a) accumulation of lead showed a definite linear increase during the period of exposure whereas aluminium and cadmium showed fluctuations. Mantle and gill tissues showed greater accumulation of metals when compared to digestive gland; (b) lead and aluminium induced lipid peroxidation was greater in tissues than the peroxidation induced by cadmium. Cadmium induced peroxidation was observed only after the day 7 of the exposure; (c) anti-oxidant enzymes activity levels were significantly higher in digestive gland and mantle than gills; (d) mantle was observed to significantly contribute to the organismal response to lipid peroxidation as indicated by high activity levels of anti-oxidant enzymes.
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    Influence of dietary curcumin and cholesterol on the progression of experimentally induced diabetes in albino rat (1995)
    Springer
    Molecular and cellular biochemistry 152 (1995), S. 13-21 
    Details
    ISSN: 1573-4919
    Keywords: curcumin ; diabetes ; hyperglycemia ; lipid peroxidation ; urinary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Effect of feeding 0.5% curcumin diet or 1% cholesterol diet was examined in albino rats rendered diabetic with streptozotocin injection. Diabetic rats maintained on curcumin diet for 8 weeks excreted comparatively less amounts of albumin, urea, creatinine and inorganic phosphorus. Urinary excretion of the electrolytes sodium and potassium were also significantly lowored under curcumin treatment. Dietary curcumin also partially reversed the abnormalities in plasma albumin, urea, creatinine and inorganic phosphorus in diabetic animals. On the other hand, glucose excretion or the fasting sugar level was unaffected by dietary curcumin and so also the body weights were not improved to any significant extent. Diabetic rats fed curcumin diet had a lowered relative liver weight at the end of the study compared to other diabetic rat groups. Diabetic rats fed a curcumin diet also showed lowered lipid peroxidation in plasma and urine when compared to other diabetic groups. The extent of lipid peroxidation on the other hand, was still higher in cholesterol fed diabetic groups compared to diabetic rats fed with control diet. Thus, the study reveals that curcumin feeding improves the metabolic status in diabetic condition, despite no effect on hyperglycemic status or the body weights. The mechanism by which curcumin improves this situation is probably by virtue of its hypocholesterolemic influence, antioxidant nature and free radical scavenging property.
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    NMR study of the selective inhibition of water permeability of rat erythrocyte membrane (1995)
    Springer
    Bioscience reports 15 (1995), S. 55-63 
    Details
    ISSN: 1573-4935
    Keywords: water transport mechanisms ; NMR ; rat erythrocytes ; tritium effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The inhibition of water diffusion across the rat erythrocyte membrane was studied by NMR using two basically different types of inhibitory agents: PCMB andin vivo irradiation. The contribution of lipid and protein to water permeability revealed the inhibitory effect of each pathway. Internal contamination with tritium (25–115 mGy) reduces water permeability due to protein modifications; for doses higher than 100 mGy the lipid mediated mechanism seems also to be impaired. The same procedure enables one to assess the extent to which the higher water permeability of rat, compared to human, erythrocyte is due to one of the two pathways.
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    Chemical and rheological investigations of the sol-gel transition in organically-modified siloxanes (1995)
    Springer
    Journal of sol gel science and technology 4 (1995), S. 151-162 
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    ISSN: 1573-4846
    Keywords: sol-gel transition ; rheology ; siloxane ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ormosils are well-known organic-inorganic sol-gel derived materials also called heteropolysiloxanes. This paper presents two basic heteropolysiloxane structures where the organic part is either a short organic chain bridging two silicon atoms for the first material or an organic polymer backbone for the second. Their synthesis is detailed and a variety of experimental techniques (IR, 13C and 29Si NMR and CP-MAS NMR, GPC) have been employed to investigate the chemical structure of these new materials. Their mechanical properties, more precisely their viscoelastic behaviour, have been evaluated using dynamic rheological techniques. The storage and loss moduli have been followed during the sol-gel transition at fixed and variable oscillation frequencies. The results have been correlated to the 29Si CP-MAS NMR informations concerning the network polycondensation and compared to a pure inorganic sol-gel material prepared from tetraethoxysilane.
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    15N resonance assignments of oxidized and reducedChromatium vinosum high-potential iron protein (1995)
    Springer
    The protein journal 14 (1995), S. 115-126 
    Details
    ISSN: 1573-4943
    Keywords: NMR ; high-potential iron protein ; 15N assignment ; heteronuclear correlation ; paramagnetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The15N resonances in reduced and oxidizedChromatium vinosum high-potential iron protein have been assigned by use of1H-1H COSY spectra and1H-15N HMQC, HMQC-COSY, and HMQC-NOESY spectra. Unambiguous assignment of 70 of 85 backbone15N resonances in the reduced protein and 62 of 85 resonances in the oxidized protein are made, as are 12 of 21 side-chain15N resonances.
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    URL: http://dx.doi.org/10.1007/BF01980323
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    Oxidation of acetophenone in a high temperature open-tubular capillary column liquid chromatographic system (1995)
    Springer
    Chromatographia 40 (1995), S. 99-101 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; High temperature open-tubular columns ; Solvent make-up ; Acetophenone oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acetophnone, a substance stable at room temperature, is readily oxidizes in a high temperature open tubular liquid chromatographic system by the residual oxygen in the mobile phase. The oxidation product is less UV absorptive and detection sensitivity decreases greatly. To prevent the oxidation, through degassing of the mobile phase is necessary.
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    The removal of endotoxins from protein solutions using column packings with aminated poly (γ-methyl L-glutamate) spheres (1995)
    Springer
    Chromatographia 40 (1995), S. 33-38 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Endotoxins ; Lipopolysaccharide ; Aminated poly(γ-methyl L-glutamate) ; Bovine serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the selective removal of endotoxins from various protein solutions using columns packed with aminated poly (γ-methyl L-glutamate) (PMLG-NH2) spheres. The PMLG-NH2 adsorbents showed a high adsorbing activity for endotoxins which had an ionic strength of μ=0.05–1.0 and pH 5.0–9.0. The endotoxin-adsorbing capacity per millitre of the wet adsorbent increased from 0.40 to 1.35 mg (E. coli O111: B4 LPS) at μ=0.2 and pH 7.0 while the aminogroup content of the adsorbent increased from 0.8 to 3.5 meq g−1. The PMLG-NH2-3.5 has an amino-group content of 3.5 meq g−1. This column packing selectively adsorbed endotoxins, without loss of the protein, from a γ-globulin or cytochromec solution which contained endotoxins at μ=0.05 and pH 7.0. On the other hand, when bovine serum albumin (BSA) was present in solution with endotoxins, both the endotoxins and the BSA were adsorbed by the column. The BSA-adsorbing activity increased with increasing amino-group content of the adsorbent. However, this undesirable adsorption was suppressed with increasing ionic strength of the buffer. As a result, when the packing which had an amino-group content of 1.5 meg g−1 was used in conditions of μ=0.2 and pH 7.0, the endotoxins were removed from a BSA-containing solution without affecting the recovery of the BSA.
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    Analysis of lignin degradation products by capillary electrophoresis (1995)
    Springer
    Chromatographia 40 (1995), S. 51-57 
    Details
    ISSN: 1612-1112
    Keywords: Column electrophoresis ; Column liquid chromatography ; Phenolic lignin degradation compounds ; Sugar degradation products ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the quantitative analysis of phenolic lignin degradation products by capillary electrophoresis (CE) with on-column UV detection has been developed. The liquid biomass solutions contain low molecular hemicellulosic sugars and phenolic lignin degradation products with various degrees of polymerization. Special attention has been paid to the monomeric phenolic components of lignin degradation fragments, e.g. derivatives of phenolic acids, aldehydes, and alcohols. Uncoated fused silica capillaries and borate-phosphate buffer systems at moderate pH conditions were used in order to separate the compounds of interest. To provide validation of the method, the same samples were analyzed independently by HPLC using gradient elution on a RP-C18 column. As sugar degradation fragment, furan-2-carboxylic acid was detected.
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    Liquid chromatography of phenolic compounds in natural water using on-line trace enrichment (1995)
    Springer
    Chromatographia 40 (1995), S. 85-90 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenolic compounds ; Ion-pair solid phase extraction ; On-line trace enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two packing materials, C18 and PLRP-S, are studied for on-line trace enrichment of phenolic compounds in water. Various precolumns of different internal diameter are also tested and the addition of an ion-pair reagent to increase retention and thus, breakthrough volumes of phenolic compounds, is studied. Best results are obtained when a PLRP-S precolumn is coupled on-line with a C18 analytical column and DAD detector. Addition of TBA considerably increases breakthrough volumes. In contrast, when a C18 precolumn is used, breakthrough volumes are lower and it is impossible to determine TCP and PCP, under the experimental conditions used, because of interference of other nonpolar compounds in the samples. The performance of the system is evaluated with river and tap water and the preconcentration of 10 ml of sample in a PLRP-S precolumn involves a linear range between 1 μg 1−1 and 20 μl−1 and limits of determination between 0.5 μg l−1 and 1 μg l−1 are obtained.
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    Screening of water samples for polar organic micropollutants using on-column sample enrichment (1995)
    Springer
    Chromatographia 40 (1995), S. 631-637 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Trace analysis ; Pesticides in tap water ; Aromatic sulphonates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methodology and instrumentation are described which allow chromatographic screening of water samples under substantially simplified conditions and at reduced cost. A single column is used to accomplish sample extraction, trace enrichment, and separation. The performance of such a system is demonstrated, and the results compared with conventionally used concepts.
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    Analysis of pyrithiones by reversed-phase high-performance liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 669-673 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Transchelation ; Zinc pyrithione and related compounds ; Antidandruff formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical procedure has been developed for the determination of zinc pyrithione in antidandruff formulations. Zinc pyrithione was converted into a stable copper complex and then analysed by reversed-phase HPLC. The proposed method allows the separation of the analyte from related pyrithiones and therefore is able to verify the compliance of cosmetic preparations with current legislation.
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    Marked differences between acetonitrile/water and methanol/water mobile phase systems on the thermodynamic behavior of benzodiazepines in reversed phase liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 84-87 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Benzodiazepines ; Solvent effects ; ACN clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two different methods were used to determine the separation factor α at different temperatures and the Gibbs-Helmholtz parameters (Δ(ΔH), Δ(ΔS)) of two adjacent benzodiazepines on a chromatogram were obtained from plots of lnα versus 1/T. We first studied each factor (fraction of water ϕ in the ACN/water mixture and column temperatureT), which controls the retention mechanism, and then we examined the simultaneous variation of all these factors. The changes in Δ(ΔH) and Δ(ΔS) in relation to a volume fraction of water ϕ in an ACN/water mixture were examined. In the ACN/water system, Δ(ΔH) was fairly constant in the acetonitrile region of ϕ≤0.52 and appears to be a roughly linear function of ϕ for ϕ≥0.52. In this system Δ(ΔS) is approximately a parabolic function of ϕ with an optimum at ϕ≅0.52. The retention mechanism of ten benzodiazepines was found to be significantly different in the methanol/water and ACN/water mixtures. The separation optimization of these ten benzodiazepines was then considered. A fraction of water of 0.43 in the ACN/water mixture and a column temperature of 44°C gave the most efficient separation conditions in the ACN/water mixture.
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    HPLC determination of urinary 2,4- and 2,6-toluendiamines as potential degradation products of polyurethane breast implants (1995)
    Springer
    Chromatographia 41 (1995), S. 661-664 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyurethane degradation products ; 2,4- and 2,6-toluendiamine ; Urine analysis ; Breast implants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase HPLC method has been developed for the urinary determination of mutagenic 2,4- and 2,6-toluendiamines. These amines are degradation products of polyurethane, a material used to cover textured silicone breast implants. FMOC-Cl was used as fluorescent derivatising agent in order to obtain a limit of detection of 15 ng/ml in urine. Pre-treatment of urine samples was by liquid/liquid extraction and urine specimens of patients after surgury were analysed.
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    HPLC analysis of flavonoids and phenolic acids and aldehydes inEucalyptus spp. (1995)
    Springer
    Chromatographia 41 (1995), S. 657-660 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyphenols ; Flavonoids ; Phenolic acids and aldehydes ; Eucalyptus spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Standards of the polyphenols occurring in wood, bark and leaf extracts ofEucalyptus spp. (i.e. flavonoids and phenolic acids and aldehydes) have been analyzed by HPLC using reversed phase columns, gradient elution and diode-array detection. The conditions used are reported.
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    Polymer encapsulated stationary phases with improved efficiency (1995)
    Springer
    Chromatographia 40 (1995), S. 657-661 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phases ; Polyencapsulated silica ; Polyacrylates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By copolymerization of silica modified with vinyl groups and acrylic acid esters in suspension highly efficient, polymeric-encapsulated stationary-phases can be prepared. The suspending liquid has to be selected such that the monomers are at least partially adsorbed on the surface and the polymer formed does not precipitate. Under these conditions stationary phases capable of speedy mass transfer can be prepared, where the reduced plate heights are between 2 and 3. The silica surface shielding is optimized so that basic and acidic solutes elute with symmetrical peak.
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    Determination of D- and L-amino acid residues in peptides with fluorescent chiral tagging reagents by high-performance liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 645-651 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral resolution of amino acids ; Pre-column derivatization ; Fluorescent chiral tagging reagents ; Stereochemical purity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Derivatization of amino acid enantiomers with fluorescent chiral Edman-type reagents, 4-(3-isothiocyanatopyrrolidin-1-yl)-7-nitro-2,1,3-benzoxadiazole [R(−)- and S(+)-NBD-PyNCS] and 4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole [R(−)-and S(+)-DBD-PyNCS], yields corresponding diastereomers separable by reversed-phase HPLC on normal achiral columns. The resolved diastereomers were detected fluorometrically at 530 nm with excitation at 490 nm for the NBD-PyNCS derivatives and at 560 nm with excitation at 450 nm for those derived from DBD-PyNCS reagents. This HPLC-derivatization method was used for evaluation of stereochemical purity for some synthetic commercial peptides. The enantioanalysis was reliable down to 0.05% racemization of the amino acid residues and a quantity of 100 μg peptide sample was usually enough for the analysis. Two acid hydrolysis methods, i.e. the standard procedure with constant-boiling hydrochloric acid (HCl) and a rapid vapor-phase procedure with HCl-trifluoroacetic acid (TFA) mixture, were compared. The later was found to be unsuitable owing to increased racemization of the amino acid residues during the hydrolysis. Judging from the results obtained for proline and leucine residues, most of the tested peptides including biologically active peptides, such as neurotensin, [d-Ala2,d-Leu5]-enkepharin and morphine tolerance peptide, possessed stereochemical purities higher than 98%. Influence of structural features of the peptides on the racemization of the amino acid residues was found to be significant.
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    HPLC-continuous-flow fast atom bombardment mass spectrometry (HPLC-CFFAB) — a convenient method for the analysis of bile acids in bile and serum (1995)
    Springer
    Chromatographia 40 (1995), S. 674-679 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mass spectrometric detection ; Fast atom bombardment ionization ; Serum bile acid ; Rat bile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to analyse bile acids in biological matrices, e.g. rat bile and human serum, high performance liquid chromatography (HPLC) was coupled to continuous-flow fast atom bombardment mass spectrometry (CFFAB-MS). A gradient elution system which had already proved to be well suited for the quantitative determination of conjugated bile acids in bile was modified to allow HPLC-CFFAB-MS-coupling. Due to the sensitivity of this coupling method it is possible to obtain more information about the biliary bile acid pattern and species-specific secondary bile acids. Furthermore, we were able to identify obviously unknown bile acid species in rat bile which most likely classify as mono-oxo and di-oxo-taurocholates (MW 513 Da, 511 Da) and mono-oxo-glycocholates (MW 463 Da). In the present study we show that using this system it is possible to determine both conjugated and unconjugated as well as sulfated bile acids, without time consuming group separation and derivatization, from rat bile and human serum. In addition, it is suggested that the method presented here should be considered for use in routine analysis.
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    Fluorescence enhancement of dansylamino acids by bovine serum albumin as mobile phase additive in microcolumn liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 159-162 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluorescence enhancement ; Bovine serum albumin ; Dansylamino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of acetonitrile and bovine serum albumin (BSA) concentrations on the signal intensity and retention behavior of dansylamino acids have been examined by using γ-cyclodextrin-bonded silica gel as the stationary phase in microcolumn liquid chromatography. Fluorescence intensities of dansylamino acids were enhanced by BSA as a mobile phase additive, e.g., detection limits of dansyl derivatives of L-Ala and L-Phe were improved by a factor of 12–18.
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    A statistical study of the correlation between k′ or log k′ and log Pow for a group of benzene and naphthalene derivatives in micellar liquid chromatography using a C-18 column (1995)
    Springer
    Chromatographia 40 (1995), S. 185-192 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid phases ; Octanol-water partition coefficient ; Benzene and naphthalene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the logarithm of the capacity factor (log k′) for fifteen benzene and naphthalene derivatives in micellar liquid chromatography with forty nine different mobile phases generally correlates better with the logarithm of the octanol-water partition coefficient (log Pow) than the capacity factor (k′). Optimum conditions are established to obtain the best linear correlations of log k′-log Pow.
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    URL: http://dx.doi.org/10.1007/BF02272169
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    Improvement of selectivity of electrochemical detection for the determination of compounds with chloro aromatic rings (1995)
    Springer
    Chromatographia 40 (1995), S. 247-252 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photolysis ; Electrochemical detection ; Drugs with chlorinated aromatic rings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Pharmaceuticals containing a thiazide ring or chlorinated aromatic ring were investigated with respect to enhanced selectivity in determination. Oxidative electrochemical detection coupled with HPLC was used to study the influence of the pH of the mobile phase under conditions of photolysis. To cover a pH range 3.9–12, the employment of a polymer column stable in alkaline media was necessary. The method offers the great advantage of derivatization without chemicals at low operating potentials, thereby providing high selectivity.
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    Separation of structural isomers using cyclodextrin-polymers coated on silica beads (1995)
    Springer
    Chromatographia 40 (1995), S. 296-302 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Structural isomer separation ; Cyclodextrin ; Polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several β-cyclodextrin (CD)-bonded stationary phases for high performance liquid chromatography (HPLC) were prepared, based on silica beads coated with a poly(alkylamine), [poly(ethyleneimine)(PEI)]. In order to obtain stationary phases with a high content of CD and maximum accessibility of the CD cavity, the functionalization was carried out after the coating, using the mono-tosyl derivative of CD as the intermediate. The ability of these supports to separate ortho, meta and para isomers of some disubstituted benzene derivatives was examined. The contribution of the amino groups of the polymer and of the CD cavity to the separation process is discussed. The resolution is mainly based on the difference in the stability of the complexes of the various isomers with CD. The influence of the amount of CD on the height of the theoretical plate is also studied.
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    A potential application for large diameter pellicular supports in the reversed phase study of ultra high molecular mass polystyrenes (1995)
    Springer
    Chromatographia 40 (1995), S. 307-312 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Polystyrene ; Pellicular ; Ultra high molecular mass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ultra high molecular mass (〉 7 million dalton) polystyrenes are prone to degradation in size exclusion chromatography. In gradient elution reversed phase HPLC they do not elute visibly on small particle size porous supports. However, large diameter C18 pellicular particles were successfully employed for reversed phase study of ultra high molecular mass (15 million dalton) polystyrenes without polymer degradation during elution. Although retention for the lower molecular mass polystyrenes was lower than on small diameter porous particles, the medium high molecular mass polystyrenes (0.5–1 million dalton) showed similar retention. The addition of small diameter porous particles in small quantities, to the large diameter pellicular particles, increased the amount of retention of the low molecular mass polystyrenes without affecting the higher molecular mass polystyrenes.
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    URL: http://dx.doi.org/10.1007/BF02290362
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    High performance liquid chromatographic determination of methyl ethyl ketone in urine as its 3-methyl-2-benzothiazolinone hydrazone derivative (1995)
    Springer
    Chromatographia 40 (1995), S. 336-340 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Methyl ethyl ketone in urine ; Derivatization ; 3-Methyl-2-benzothiazolinone hydrazone ; Comparison with GC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A HPLC method for the determination of methyl ethyl ketone (MEK) in urine after derivatization with 3-methyl-2-benzothiazolinone hydrazone is proposed. The calibration curve for the ketone was linear, ranging between 0.23–10 mg/L, with a detection limit of 0.025 mg/L. The results were compared to those obtained by GC-MS, coupled to the headspace technique. MEK derivatization and the derivative purification processes were verified with respect to the main variables such as reaction temperature, reagent concentration, probable interferences and enrichment phase. The method is simple and reliable and shows a good sensitivity.
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    Liquid chromatographic analysis of sulfornamides in foods (1995)
    Springer
    Chromatographia 40 (1995), S. 382-386 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sulfonamides in foodstuffs ; Honey ; Milk ; Eggs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure for the simultaneous determination of several sulfonamides in different foods, such as honey, milk and eggs is proposed. The analysis is carried out using reversed phase liquid chromatography with spectrophotometric detection. Optimization of the mobile phase led to good separation and a short analysis time when an initial isocratic step with a 3∶97 acetonitrile: water mixture was used for 5 minutes, followed by a linear gradient up to a 40∶60 mixture over 15 min. The proposed method is suitable for routine quality control analysis to ensure the absence of sulfonamides in foods. Recovery studies yielded good results for all food samples because there were no interferences from the matrices.
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    URL: http://dx.doi.org/10.1007/BF02269899
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    Determination of aflatoxins in peanut meal by LC/MS with a particle beam interface (1995)
    Springer
    Chromatographia 40 (1995), S. 411-416 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Particle beam LC/MS interface ; Capillary columns for LC ; Mycotoxins ; Peanut meal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the analysis of aflatoxins in food extracts, based on liquid chromatography/mass spectrometry interfacing, is presented. The chromatographic separation was performed with a reversed phase packed capillary column coupled with a modified particle beam interface capable of handling microliter per minute flow rates. This system allows higher overall sensitivity and easier operation procedures. The method has proved to be particularly suitable for the analysis of the toxins in very complex matrices. The specificity of electron impact ionization allowed positive identification of the aflatoxins with an excellent response linearity for accurate quantitation.
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    URL: http://dx.doi.org/10.1007/BF02269904
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    Retention parameters of some isomeric 2-benzoylbenzoic acids in reversed-phase ion-pair high performance thin-layer and column chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 453-457 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Reversed phase ; 2-benzoylbenzoic acids ; Anionic and cationic counter ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by Δlog k′ and ΔRM values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated.
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    URL: http://dx.doi.org/10.1007/BF02269912
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    Determination of D- and L-amino acids in biological samples by two-dimensional column liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 6-14 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Two-dimensional separation ; D- and L-amino acids ; Enantioseperation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A two-dimensional, column liquid chromatographic system is used for the determination of the D- and L-enantiomers of amino acids in biological samples. Separation of the amino acids is first on ion-exchange column by gradient elution with a sodium citratesodium chloride buffer. Enantioseparation is by subsequent injection of 3 μl heart-cuts of the individual amino acids onto a second column with a chiral crown ether stationary phase. Finally, fluorescence detection is after post-column labelling of the amino acids using ano-phthalaldehyde-2-mercaptoethanol reagent solution. The high separation power and selectivity of the system allow processing of complex samples with hardly any additional treatment and the determination of small quantities of D-amino acids in the presence of excess L-form. Applicability of the system is illustrated by the determination of D- and L-aspartate, serine, glutamate and alanine in various complex biological samples, such as protein hydrolysates, urine and biotechnological and food samples. Data are given on detectability, repeatability and linearity.
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    Simultaneous determination of preservatives, sweeteners and antioxidants in foods by paired-ion liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 43-50 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion pair LC ; Sweeteners, preservatives and antioxidants ; Food additive analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na and acesulfame-K), preservatives (sodium dehydroacetate, sorbic acid, salicyclic acid, benzoic acid, succinic acid, methyl-para-hydroxybenzoic acid, ethylpara-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, isopropyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 mM aqueous α-hydroxy-isobutyric acid solution (pH 4.5) (2.2 ∶ 3.4 or 2.4 ∶ 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a C18 column with a flow rate at 1.0 mL/min and detection at 233 nm were used. This method was found to be very reproducible with detection limits ranged from 0.15 to 3.00 μg. The retention factor (k) of each additive could be affected by concentrations of hexadecyltrimethylammonium bromide and α-hydroxyisobutyric acid, and pH and ratio of mobile phase. The presence of additives in some food samples was determined.
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    URL: http://dx.doi.org/10.1007/BF02274194
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    Prediction of precision from signal and noise measurement in liquid chromatography: Mathematical relationship between integration domain and precision (1995)
    Springer
    Chromatographia 41 (1995), S. 75-83 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Limit of detection ; Precision ; Uncertainty prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The precision of integration over noisy instrumental output for quantitative analysis is studied. A probability theory is developed to predict the relative standard deviation (RSD) of integration results over an integration domain from one-point integation (peak height measurement) to entire area integration in HPLC. Common integration modes of horizontal zero line and oblique zero line are taken into account, but no peak overlap is assumed. The question of the analytical superiority of peak height measurement or integration for quantitation is answered. In the HPLC apparatus used, the minimum RSD of measurements is found in the integration domain of ca. ±0.5 σ for analytes [peaks are approximated by the Gaussian signal of width, σ (standard deviation)]. The RSD of integration measurements is also shown to depend on the stochastic properties of back-ground noise (uncorrelated noise and correlated 1/f type noise). The theoretical conclusion is verified by Monte Carlo simulation and HPLC experiments for some aromatic compounds.
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    Ion-pair reversed-phase and low-molecular-weight aqueous gel permeation high-performance liquid chromatography methods for the determination of amoxicillin oligomersa (1995)
    Springer
    Chromatographia 41 (1995), S. 651-656 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair and GPC separations ; Amoxicillin oligomers ; β-Lactam ring polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polymeric substances formed from concentrated sodium amoxicillin in an aqueous solution have been separated using two high-performance liquid chromatographic methods. We used a C18 reversed-phase column with tetrabutylammonium chloride as an ion-pairing agent with an acetonitrile gradient and a TSKgel G2500PWxl column with water as the solvent for gel permeation chromatography. The separated materials, ranging in size from the monomer to the tetramer, have been characterized by functional-group chemical analysis, while the identification of the piperazine-2,5-dione was done using a pure standard. A greater number of peaks which were also better defined were obtained using the ion-pair reversed-phase method, and open and closed beta-lactam ring polymer forms could be distinguished. Using the gel permeation method, only a few monomer, piperazine-2,5-dione, dimer, trimer and combined amoxicillin trimer and tetramer peaks were obtained with water, although those obtained were quite well defined. The data on the time-course of formation of the oligomers and the amoxicillin degradation product were virtually identical by both methods.
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    URL: http://dx.doi.org/10.1007/BF02267799
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    Signal enhancement by on-column fluorimetric detection in gradient elution of dansyl amino acids in liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 148-152 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-column fluorimetric detection ; Gradient elution ; Dansyl amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fluorimetric detection in the presence of a stationary phase has been applied to gradient elution of dansyl amino acids in liquid chromatography. A 1.5 mm ID quartz tube packed with the same materials as the separation column was employed for the flow cell. Conventional-size columns were employed. The peak height of analytes increased with increasing retention owing to focusing and environmental effects of the stationary phase, leading to improvements in sensitivity, which was pronounced for analytes eluting late. The lower the gradient, the larger the improvement in sensitivity achieved. Detection limits were improved by a factor of up to 5.1 by fluorimetric detection using the packed flow cell, compared with those achieved using a common empty flow cell.
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    URL: http://dx.doi.org/10.1007/BF02267946
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    A study of the behaviour of some new column materials in the chromatographic analysis of Cinchona alkaloids (1995)
    Springer
    Chromatographia 41 (1995), S. 153-160 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; LC-MS ; Cinchona alkaloids ; New column packing materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing materials specially designed for the separation of basic compounds has been studied using mobile phases without the special additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied. The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silicabased C18 material proved superior to the polymer materials tested.
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    A phase II and pharmacokinetic study of 6S-leucovorin plus 5-fluorouracil in patients with colorectal carcinoma (1995)
    Springer
    Investigational new drugs 13 (1995), S. 149-155 
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    ISSN: 1573-0646
    Keywords: leucovorin ; colorectal cancer ; pharmacokinetics ; chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Leucovorin (LV) is commonly used as a modulator of 5-fluorouracil (5-FU) cytotoxicity. In patients with colon cancer, the addition of LV to 5-FU improves response rates, and in some trials has improved survival in advanced disease and in the adjuvant setting. Leucovorin is generally administered as a racemic mixture, but the isomers differ substantially in pharmacokinetics and biological activity, with 6S-LV the predominant active component. The current study was undertaken to determine the effect of 6R on the pharmacokinetics of 6S-LV, and to characterize the toxicity and antitumor effect of 5-FU when administered with 6S-LV to patients with advanced colorectal carcinoma. Thirty patients were treated with weekly 5-FU plus high dose 6S-LV. To determine the effects of 6R-LV on the pharmacokinetics of 6S-LV, 20 patients were randomly assigned to receive either 250 mg/m2 6S-LV or 500 mg/m2 6R,S-LV as a 2 hour IV infusion on day −2, and the other preparation on day −1, with pharmacokinetics measured each day. The presence of 6R-LV had no effect on the AUC, Clp, Cmax, or terminal phase t1/2 of 6S-LV. The overall response rate was 40% (C.I. 23–60%). The most frequent toxicities were gastrointestinal. In this small cohort, scheduled and delivered dose intensity was positively associated with response (p=0.05). These results show that there is no pharmacokinetic advantage to the use of 6S-LV rather than 6R,S-LV as a modulator of 5-FU.
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    Invertomers at nitrogen in aziridine carboxylates by mltltinuclear (1H,13C,17O, and15N) NMR study (1995)
    Springer
    Chemistry of heterocyclic compounds 31 (1995), S. 1071-1078 
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    ISSN: 1573-8353
    Keywords: NMR ; 1H NMR ; 13C NMR ; 17O NMR ; 15N NMR ; aziridine-carboxylates ; configurational analysis ; conformational analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A confrgurational and conformational study of NH, N-acetyl- and N-sulfonylaziridine carboxylates is performed by1H ,13C,17O, and15N NMR spectroscopy. The presence of acetyl and su fonyl groups on the ring nitrogen atom seems to reduce greatly the configurational stability at nitrogen.
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    Pharmacokinetics of Antimony in Patients Treated with Sodium Stibogluconate for Cutaneous Leishmaniasis (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 113-116 
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    ISSN: 1573-904X
    Keywords: antimony ; sodium stibogluconate ; pentavalent antimonials ; pharmacokinetics ; cutaneous leishmaniasis ; antimony in whole blood ; urinary excretion of antimony ; interpatient variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of Sb was examined in 29 patients with cutaneous leishmaniasis following the intramuscular administration of a dose of sodium stibogluconate equivalent to 600 mg of Sb. Blood was sampled at different time intervals from each patient and Sb was measured in whole blood by electrothermal atomic absorption spectrophotometry after an appropriate dilution with Triton X-100. The 24-hr urine- was also collected and analyzed similarly. The blood concentration-time data conformed to the one-compartment open model with mean and (SEM) of the apparent first-order rate constants for absorption (ka) and elimination (kd) of 1.71 (0.15) and 0.391 (0.016) hr−1, respectively. The maximum concentration of Sb achieved was 8.77 (0.39) mg/L and the peak time was 1.34 (0.09) hr. The total body clearance (TBC) and the volume of distribution (Vd) were 17.67 (1.38) L/hr and 45.7 (2.6) L, respectively, assuming a complete absorption. The fraction of dose of Sb excreted in the urine was 0.80 (0.07) and the renal clearance was 12.7 (1.16) L/hr. The frequency distribution pattern of the area-under-the-curve (AUC) appears to be bimodal and separates patients into those with low exposure to Sb (AUC = 11.7-29.04 mg.hr/L) (i.e., rapid eliminators) and those with high exposure to Sb (AUC = 31.5-49.1 mg.hr/ L) (i.e., slow eliminators). This may explain the variability observed in the response to treatment of leishmaniasis with sodium stibogluconate.
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    Assessment of Toxicokinetics and Toxicodynamics Following Intravenous Administration of Etoposide Phosphate in Beagle Dogs (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 117-123 
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    ISSN: 1573-904X
    Keywords: BMY-40481 ; etoposide phosphate ; etoposide ; pharmacokinetics ; pharmacodynamics ; dogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The toxicokinetics and toxicodynamics of etoposide phosphate (BMY-40481), a water soluble phosphate ester derivative of etoposide, were investigated in beagle dogs (N = 4) following 5 min i.v. infusion doses equivalent to 57, 114 and 461 mg/m2 of etoposide. The doses were administered in sequence starting with the low dose. There was a 28 day wash-out period between the doses. Serial blood samples were collected over 32 hr and the levels of intact BMY-40481 and etoposide in plasma were measured using validated HPLC assays. Hematology profiles were obtained at pre-dose, and twice a week post-dose for 28 days to correlate systemic exposure to etoposide and hematologic toxicity. Following i.v. administration, plasma concentrations of BMY-40481 declined rapidly. For the 3 doses, mean t1/2 of BMY-40481 ranged from 0.11 - 0.17 hr (6.6-11 min). The mean Cmax and AUC values of BMY-40481 ranged from 1.72 - 40.5 µg/ml and 0.16 - 4.14 hr.µg/ml, respectively. Both systemic clearance and steady state volume of distribution of BMY-40481 decreased significantly at the high dose. In contrast, the mean Cmax and AUC values of etoposide ranged from 5.46 - 39.4 µg/ml and 2.28 - 22.6 hr.µg/ml, respectively. Cmax occurred at the end of infusion (5 min) at all dose levels, indicating that etoposide was rapidly formed from BMY-40481. The apparent systemic clearance (range: 342 - 435 ml/min/m2) and apparent steady state volume of distribution (range: 21.5 - 26.6 1/m2) of etoposide were dose-independent. The AUC of etoposide was significantly correlated with hematologic toxicity, i.e., percent decreases in white blood count (WBC), absolute neutrophil count (ANC) and platelets. The relationship was best described by the sigmoid Emax model for WBC and ANC, and by a simple linear model for platelets. Hemoglobin showed slight decreases which did not correlate with etoposide AUC. In summary, BMY-40481 is rapidly and extensively converted to etoposide; etoposide exhibits linear kinetics; and except for hemoglobin, hematologic toxicity is significantly correlated with etoposide exposure.
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    The Effect of Food on Pharmacokinetics of Zalcitabine in HIV-Positive Patients (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1462-1465 
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    ISSN: 1573-904X
    Keywords: pharmacokinetics ; food ; interaction ; zalcitabine ; HIV infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to determine the effect of food on the pharmacokinetics of zalcitabine in HIV-positive patients. Methods. Twenty patients received single oral 1.5 mg doses of zalcitabine with and without a standard breakfast in an open-label, randomized crossover study with at least a one week washout period between treatments. Serial blood and urine samples were collected over 24 hours and assayed for zalcitabine by a modified GC/MS method. Results. Administration with food delayed and prolonged absorption resulting in a decrease of approximately 39% in maximal plasma concentrations compared to dosing under fasting conditions. Comparison of plasma AUC values indicated a small (14%) reduction in bioavailability when given with food. Approximately 59% and 45% of the dose were excreted unchanged in the urine under fasting and fed conditions, respectively. Conclusions. The results of this study show that the administration of zalcitabine with food results in a mild reduction in bioavailability. Although these changes are not expected to be of clinical importance, further studies must be conducted for confirmation.
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    A Novel Oligodeoxynucleotide Inhibitor of Thrombin. II. Pharmacokinetics in the Cynomolgus Monkey (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1943-1947 
    Details
    ISSN: 1573-904X
    Keywords: GS-522 ; oligodeoxynucleotide ; thrombin ; pharmacokinetics ; monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine the pharmacokinetics of GS-522, an oligodeoxynucleotide (GGTTGGTGTGGTTGG) inhibitor of thrombin, after constant infusion and bolus administration in the cynomolgus monkey. Methods. Using a stability indicating HPLC method, the GS-522 plasma concentration versus time data were obtained after constant infusion (0.1, 0.3, 0.5 mg/kg/min) and bolus administration (11.25 and 22.5 mg/kg). Plasma data after bolus administration was fit to a three-compartment model. Results. The half-lives for the α and β phases were 1.4 and 5.4 min, respectively. Steady state GS-522 concentrations were reached within 10 minutes after initiation of constant infusions. Termination of infusions resulted in a rapid elimination of GS-522 with an average elimination half-life equal to 1.5 min. The Vss calculated from both the constant infusion and bolus data approximated the blood volume of the monkey. Substitution of the phosphodiester backbone at the 3′ end of GS-522 with two phosphorothioate linkages did not substantially effect the elimination half-life upon termination of infusion. Conclusions. These data in conjunction with published biodistribution data suggest that oligodeoxynucleotides are rapidly cleared from plasma by tissue uptake and that little efflux back into blood takes place. Additionally, strategies designed to increase oligodeoxynucleotide resistance to exonucleases will not dramatically increase plasma half-lives.
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    Regional Drug Delivery II: Relationship Between Drug Targeting Index and Pharmacokinetic Parameters for Three Non-Steroidal Anti-Inflammatory Drugs Using the Rat Air Pouch Model of Inflammation (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1987-1996 
    Details
    ISSN: 1573-904X
    Keywords: drug targeting index ; regional administration ; pharmacokinetics ; rat air pouch model ; inflammation ; non-steroidal anti-inflammatory drugs ; diclofenac ; piroxicam ; S[ + ]ibuprofen ; albumin flux
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To quantify the advantage gained by direct administration to a target site for two non-steroidal anti-inflammatory drugs (NSAIDs) piroxicam and diclofenac in the rat air pouch model of inflammation. To derive a model relating drug targeting index (DTI) to the pharmacokinetic parameters of the target and systemic sites, and to compare predictions with observations. Methods. DTI was calculated based on area under the concentration time curve at target (pouch) and systemic site (venous blood) following administration into and sampling from both sites. A model was derived relating DTI to systemic clearance, target permeability, plasma protein binding and fraction of the targeted dose that is systemically available. Results. Both NSAIDs exhibited linear pharmacokinetics over the dose ranges studies. They differed primarily in total body clearance which was approximately 16 fold greater for diclofenac (213 ml hr−l per 250 g) than piroxicam (13 ml hr−l per 250 g). Observed DTIs (11, 114 and 276 for piroxicam, S[ + ]ibuprofen [studied previously] and diclofenac) were ranked in order of total body clearance but were approximately 7.5 fold lower than predicted (101, 700 and 2214 respectively). Conclusions. The discrepancy was explained by the influx of the plasma binding protein, albumin, into the target site due to increased vascular permeability associated with the inflammatory response. The originally derived equation for DTI, which assumed only unbound drug diffuses across the target site, was modified to take into account the simultaneous flux of bound drug.
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    URL: http://dx.doi.org/10.1023/A:1016212510900
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  • 91
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    Effects of Gender, Pregnancy, and Anesthesia on the Pharmacokinetics of Zidovudine in Rats (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1647-1651 
    Details
    ISSN: 1573-904X
    Keywords: zidovudine ; gender ; anesthesia ; pregnant ; pharmacokinetics ; rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The effects of gender, pregnancy and anesthesia on the pharmacokinetics of zidovudine (AZT) were studied in rats. Methods. Unanesthetized male (MR), female (FR) and pregnant (day 20, PR) rats received 50 mg/kg AZT via a jugular vein cannula. Female (FRA), pregnant (day 20, PRA) and pregnant (day 20, PRR) rats maintained under ketamine: acepromazine:xylazine anesthesia also received 50 mg/kg AZT. Two fetuses were removed at each sampling time from the PRR group. Plasma samples were collected and analyzed by RIA. Results. With the exception of a lower non-renal clearance in female rats, there were no gender differences in the disposition of AZT. No significant differences were noted in total clearance, non-renal clearance or volume of distribution between pregnant and female rats, however, significant differences in renal clearance values were evident. Anesthesia resulted in decreased total, renal and non-renal clearances in female and pregnant rats. The removal of fetuses during the experiments did not alter the total clearance of AZT in pregnant rats, however, renal clearance and volume of distribution were decreased by cesarian section. Conclusions. The rat appears to be a suitable laboratory animal model for investigating AZT disposition during pregnancy. However, results of pharmacokinetic studies when animals are maintained under anesthesia with ketamine :acepromazine:xylazine must be interpreted with caution.
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    URL: http://dx.doi.org/10.1023/A:1016293017318
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  • 92
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    Design for Cell-Specific Targeting of Proteins Utilizing Sugar-Recognition Mechanism: Effect of Molecular Weight of Proteins on Targeting Efficiency (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 209-214 
    Details
    ISSN: 1573-904X
    Keywords: protein targeting ; sugar recognition ; pharmacokinetics ; molecular weight ; liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hepatic targeting of proteins utilizing the sugar-recognition mechanism was investigated in mice after intravenous injection. Five proteins with different molecular weights, i.e., bovine γ-globulins (IgG), bovine serum albumin (BSA), recombinant human superoxide dismutase (SOD), soybean trypsin inhibitor (STI), and chicken egg white lysozyme (LZM), were modified with 2-imino-2-methoxyethyl 1-thiogalactoside to obtain galactosylated proteins (Gal-IgG, Gal-BSA, Gal-SOD, Gal-STI, and Gal-LZM). The numbers of galactose residues were 38, 20, 11, 6, and 5 for Gal-IgG, Gal-BSA, Gal-SOD, Gal-STI, and Gal-LZM, respectively. All galactosylated proteins were dose-dependently taken up by the liver and the relative amount accumulated in the liver was decreased with an increase of the administered dose. At low doses (0.05 and 0.1 mg/kg), Gal-IgG, Gal-BSA, and Gal-SOD could be taken up by the liver up to more than 70–80% of dose within 10 min after intravenous injection, but the maximum amounts accumulated in the liver were approximately 40 and 30% of the dose for Gal-STI and Gal-LZM, respectively. Pharmacokinetic analysis revealed that the hepatic uptake clearance (CLliver) was quite different around the molecular weight of 32 kDa and correlated with the amount delivered to the liver; Gal-IgG, Gal-BSA, and Gal-SOD has a large CLliver that is close to the hepatic plasma flow rate (85 ml/hr), whereas those of Gal-STI and Gal-LZM were approximately 10 ml/hr at low doses. As for the total amount accumulated in the liver, high glomerular filtration rate of Gal-STI and Gal-LZM was also shown to cause insufficient delivery to the liver apart from being caused by their low CLliver.
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    URL: http://dx.doi.org/10.1023/A:1016222808484
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  • 93
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    Evaluation of Intestinal Absorption into the Portal System in Enterohepatic Circulation by Measuring the Difference in Portal–Venous Blood Concentrations of Diclofenac (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 880-883 
    Details
    ISSN: 1573-904X
    Keywords: portal–venous blood concentration difference ; enterohepatic circulation ; diclofenac ; portal system ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. We evaluated the first-pass effects in vivo by the intestine and liver during enterohepatic circulation (EHC) by simultaneously measuring the portal and venous plasma concentrations of the rat. Methods. The venous and upper portal blood vessels were cannulated through the jugular and the pyloric veins, respectively, to obtain simultaneously blood samples from both sites. After diclofenac was injected as a bolus through the jugular vein, the concentrations of diclofenac in the portal and jugular veins were measured at time intervals. The absorption rate from the intestinal tract into the portal system was determined using the portal–venous difference in plasma concentrations of diclofenac, considering 40% partitioning of diclofenac into erythrocytes. Results. After one hour, the plasma concentration in the portal vein was always higher than that in the jugular vein in awakening rats with intact EHC (portal–venous blood concentration difference). No portal–venous difference was observed in awakening rats with bile-duct cannulation. Therefore, it was concluded that this portal–venous concentration difference was not due to the hepatic clearance but to diclofenac reabsorption from the intestinal tract. Conclusions. Appropriately 40% of the dose of diclofenac was reabsorbed over 8 hours from the intestinal tract into the portal system. By comparing the reabsorbed amounts in the portal system and in the systemic circulation, the hepatic extraction ratio in vivo (FH) of diclofenac was estimated to be 63%.
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    URL: http://dx.doi.org/10.1023/A:1016217221977
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  • 94
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    Effect of Corticosteroid Binding Globulin on the Pharmacokinetics of Prednisolone in Rats (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 902-904 
    Details
    ISSN: 1573-904X
    Keywords: corticosteroid binding globulin ; transcortin ; pharmacokinetics ; free hormone hypothesis ; prednisolone ; methylprednisolone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The effect of exogenous corticosteroid binding globulin (CBG) on the pharmacokinetics of intravenous prednisolone was determined in rats to test the “free hormone hypothesis.” Methods. A dose of CBG to yield 95% binding with 1000 ng/ml of prednisolone in vitro in rat plasma or saline was administered before dosing 2 mg/kg of prednisolone hemisuccinate or methylprednisolone intravenously. Drug concentrations in plasma samples were assayed by HPLC. Results. Single administration of CBG decreased apparent prednisolone clearance by 56% (155 to 66 ml/min/kg) and reduced apparent Vss by 35% (4.1 to 2.7 L/kg) (p〈0.001). Methylprednisolone pharmacokinetics, studied as a negative control because the drug does not bind to CBG, did not change. Conclusions. The corticosteroid bound to CBG does not appear to be available for removal by clearance organs.
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    URL: http://dx.doi.org/10.1023/A:1016225423795
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  • 95
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    Metabolism of Dynorphin A 1-13 in Human Blood and Plasma (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1165-1170 
    Details
    ISSN: 1573-904X
    Keywords: dynorphin Al-13 ; opioid peptides ; metabolism ; pharmacokinetics ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. A detailed investigation of the metabolic routes and rates of Dyn A1-13 in human blood and plasma was performed. Methods. Human plasma was incubated at 37°C with dynorphin A 1-13 (Dyn Al-13, 15-20 µM). The generated dynorphin fragments were separated by a new ion-pair chromatographic method and identified by matrix assisted laser desorption mass spectroscopy. The kinetic behavior of parent compound and metabolites was evaluated in the absence and presence of enzyme inhibitors. Results. The major plasma metabolites of Dyn Al-13 were Dyn A1-12, A2-12, A4-12 and A4-8. Further metabolites were Dyn A2-13, A3-13, A3-12, A5-12, A6-12, A7-12, Al-10, A2-10, A2-8 and A3-8. At 37°C, Dyn Al-13 had a half-life of less than one minute in plasma and blood. Plasma half-lives of major metabolites ranged between 0.5 and 4 min. Inter-and intra-individual differences in healthy volunteers were 30% (c.v.). Dyn Al-13 is mainly metabolized by carboxypeptidases to Dyn Al-12 (80%) and by aminopeptidases to Dyn A2-13 (15%). Dyn A1-12 and Dyn A2-13 are predominantly converted into Dyn A2-12 (67% of Dyn Al-13). Subsequent metabolic steps yield Dyn A3-12 (16%), Dyn A4-12 (37%) and Dyn A4-8 (33%). Aminopeptidases generate Dyn A2-12, A3-12, A4-12, A5-12. ACE metabolizes Dyn Al-12 (19%), A2-12 (33%), A3-12 (34%) and A4-12 (46%). Bestatin-sensitive endopeptidases (possibly endopeptidase 24.11) metabolize 30% of Dyn A2-12. Dyn A4-8 is formed via Dyn A4-12 (23% of Dyn A4-12) and Dyn A2-10 (37% of Dyn A2-10). Conclusions. The combination of enzyme inhibition experiments and noncompartmental kinetic analysis proved to be a powerful tool for the detailed evaluation of the metabolic fate of Dyn Al-13 in human blood and plasma.
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    URL: http://dx.doi.org/10.1023/A:1016211910107
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  • 96
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    Pharmacokinetic Studies of Methotrexate in Plasma and Synovial Fluid Following IV Bolus and Topical Routes of Administration in Dogs (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1474-1477 
    Details
    ISSN: 1573-904X
    Keywords: methotrexate ; pharmacokinetics ; synovial fluid ; poloxamer gel ; muscle tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The pharmacokinetic properties of methotrexate (MTX) in the plasma and synovial fluid (SF) after bolus IV and topical administration were studied in dogs to assess the feasibility of topical delivery of MTX for the treatment of rheumatoid arthritis. Methods. A MTX gel in Poloxamer 407 containing an absorption enhancer was formulated and topically applied on the elbow and stifle joints of dogs. SF was collected by inserting a needle with syringe into the joint space. Drug concentrations in the plasma, SF and muscle tissues were determined using a HPLC method with fluorimetric detection. Results. Peak MTX concentrations in SF occurrred at 38 ± 5 min following bolus IV dose, indicating the presence of a substantial diffusion barrier between the plasma and SF. The plasma/SF concentration ratios of 1.16 ± 0.25 were maintained after the attainment of distribution equilibrium between the two compartments. The t1/2 values in the plasma (11.2 ± 1.2 hr) and SF (12.7 ± 3.7 hr) were similar during the elimination phase, while the MRT in SF (3.24 ± 0.21 hr) was longer than that in plasma (2.56 ± 0.20 hr), probably due to the slow distribution of MTX to SF. After topical dose, MTX concentrations in plasma reached the steady state at ~4 hr, lasting for ~20 hr.The bioavailability of MTX from the gel was 11.8 ± 3.3% of the applied dose, but muscle tissues beneath the gel application site had significantly higher levels of MTX than untreated muscle tissues. There was no statistical difference in SF concentrations of MTX between drug treated and untreated joints 24 hr after topical dose. Conclusions. Topical delivery of MTX in a hydrophilic gel achieved a sustained C/t profile in plasma and higher drug levels in muscle tissues underneath the dosing site, implicating the potential therapeutic value of the topical formulation. Methods. A MTX gel in Poloxamer 407 containing an absorption enhancer was formulated and topically applied on the elbow and stifle joints of dogs. SF was collected by inserting a needle with syringe into the joint space. Drug concentrations in the plasma, SF and muscle tissues were determined using a HPLC method with fluorimetric detection. Results. Peak MTX concentrations in SF occurrred at 38 ± 5 min following bolus IV dose, indicating the presence of a substantial diffusion barrier between the plasma and SF. The plasma/SF concentration ratios of 1.16 ± 0.25 were maintained after the attainment of distribution equilibrium between the two compartments. The t1/2 values in the plasma (11.2 ± 1.2 hr) and SF (12.7 ± 3.7 hr) were similar during the elimination phase, while the MRT in SF (3.24 ± 0.21 hr) was longer than that in plasma (2.56 ± 0.20 hr), probably due to the slow distribution of MTX to SF. After topical dose, MTX concentrations in plasma reached the steady state at ~4 hr, lasting for ~20 hr.The bioavailability of MTX from the gel was 11.8 ± 3.3% of the applied dose, but muscle tissues beneath the gel application site had significantly higher levels of MTX than untreated muscle tissues. There was no statistical difference in SF concentrations of MTX between drug treated and untreated joints 24 hr after topical dose. Conclusions. Topical delivery of MTX in a hydrophilic gel achieved a sustained C/t profile in plasma and higher drug levels in muscle tissues underneath the dosing site, implicating the potential therapeutic value of the topical formulation.
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    URL: http://dx.doi.org/10.1023/A:1016231303689
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  • 97
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    Intra- and Inter-Subject Variabilities of CGP 33101 after Replicate Single Oral Doses of Two 200-mg Tablets and 400-mg Suspension (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1878-1882 
    Details
    ISSN: 1573-904X
    Keywords: CGP 33101, intra-subject variability ; inter-subject variability ; pharmacokinetics ; healthy subjects ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to use a replicate designed trial to assess the overall, intra- and inter-subject variabilities in pharmacokinetic parameters of CGP 33101 after oral administration of tablets relative to that of powder suspended in water, and to determine the relative proportion of the intra-subject variance to the overall variability. Methods. Sixteen healthy subjects were randomly assigned to four groups to receive tablets and suspension twice in four different treatment sequences. The plasma concentration-time profile of CGP 33101 was characterized in terms of Cmax, Tmax, and AUC. Bioavailability of tablets relative to suspension and intra- and inter-subject variability were assessed by statistical analysis. Results and Conclusions. The overall variabilities in absorption kinetics of CGP 33101 in healthy subjects were small with CV's of the population mean values for AUC and Cmax less than 26% for both tablets and suspension. Contribution of intra-subject variability to the overall variability was also small (~20%). Both the overall and intra-subject variabilities of AUC and Cmax after suspension were larger than after the tablets. However, the differences in variability between tablets and suspension were not statistically significant (p 〉 0.05). The tablet formulation was bioequivalent to suspension in terms of rate and extent of absorption based on 90% conventional confidence intervals (for AUC and Cmax) and Wilcoxon rank-sum test (for Tmax).
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    URL: http://dx.doi.org/10.1023/A:1016275402723
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  • 98
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    Effect of Probenecid on the Enantioselective Pharmacokinetics of Oxprenolol and Its Glucuronides in the Rabbit (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1964-1967 
    Details
    ISSN: 1573-904X
    Keywords: enantioselectivity ; pharmacokinetics ; oxprenolol ; oxprenolol glucuronides ; probenecid ; active renal secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the effect of probenecid on the stereoselective pharmacokinetics of oxprenolol and its glucuronides in the rabbit. Methods. An oral dose of 50 mg/kg racemic oxprenolol was given to nine rabbits twice, in random sequence with and without the concurrent administration of probenecid. Oxprenolol enantiomers were determined in plasma and urine by an enantioselective HPLC method. Oxprenolol glucuronides were measured in plasma and urine after enzymatic hydrolysis. Results. The disposition of the oxprenolol enantiomers in rabbits is stereoselective, mainly due to a difference in metabolism. Renal excretion is only a minor elimination route for unchanged oxprenolol, and the renal clearances of the enantiomers are similar. Pre-treatment with probenecid did not affect the plasma concentrations of the oxprenolol enantiomers, but there was a slight decrease in their urinary excretion. The plasma concentrations of the oxprenolol glucuronides are much higher than those of the parent enantiomers, and those of (S)-glucuronide are about twice those of its antipode. About 10% of the oxprenolol dose is excreted in the urine as glucuronides. The renal clearances of both glucuronides are similar, and markedly higher than the creatinine clearance. After probenecid, the mean glucuronide plasma levels were markedly higher, with for both glucuronides a more than twofold increase in mean AUC. Probenecid decreased the renal clearance of both glucuronides to about 30%. Moreover, it decreased slightly the formation clearance of (S)-glucuronide, while the formation clearance of (R)-glucuronide was not significantly influenced. Conclusions. Our results show that in the rabbit, both oxprenolol glucuronide diastereomers are actively secreted by the kidney, and that this process is inhibited by probenecid.
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    URL: http://dx.doi.org/10.1023/A:1016204309083
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  • 99
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    Microdialysis Sampling to Determine the Pharmacokinetics of Unbound SDZ ICM 567 in Blood and Brain in Awake, Freely-Moving Rats (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 291-294 
    Details
    ISSN: 1573-904X
    Keywords: brain microdialysis ; blood microdialysis ; pharmacokinetics ; free drug concentration ; SDZ ICM 567
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The free concentrations of the serotoninergic 5-HT3 antagonist SDZ ICM 567 in blood and in the central nervous system were examined in awake, freely-moving rats using blood and brain microdialysis coupled to liquid chromatography. Microdialysis probes were implanted in the jugular vein and in the frontal cortex and dialysis samples were simultaneously collected from both sites. Pharmacokinetic parameters were calculated after a 10 mg/kg intravenous dose of [14C]SDZ ICM 567. The elimination half lives measured in whole blood, brain and blood microdialysates were similar (≃1.7 h). The AUC0–5h corresponding to the unbound drug was 462 ± 142 ng · ml−1 · h in blood dialysate, not significantly different from the AUC corresponding to the free concentration in whole blood, i.e. 586 ± 63 ng · ml−1 h. The free fraction in blood obtained in vitro by equilibrium dialysis (21%) or by microdialysis (19%) was not statistically different from that obtained in vivo (17%) in microdialysis experiments. The unbound concentrations (AUC0–5h) of SDZ ICM 567 in the brain cortex were 86 ± 24 ng · ml−l - h, lower than those expected from unbound blood concentrations, suggesting an active transport out of the central nervous system. Finally, microdialysis sampling allowed the determination of pharmacokinetic parameters of SDZ ICM 567 in blood and brain as well as the estimation of the free fraction of drug in blood.
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    URL: http://dx.doi.org/10.1023/A:1016247413935
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  • 100
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    The Influence of Regional Deposition on the Pharmacokinetics of Pulmonary-Delivered Human Growth Hormone in Rabbits (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 356-359 
    Details
    ISSN: 1573-904X
    Keywords: growth hormone ; pulmonary ; pharmacokinetics ; gamma scintigraphy ; drug delivery ; rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pulmonary deposition and pharmacokinetics of human growth hormone (hGH), administered by aerosol and instillate, in formulations containing 99mTc-DTPA (for gamma scintigraphic imaging) have been studied in five male New Zealand White rabbits. Gamma scintigraphy indicated that the peripheral:central deposition tended to be greater for aerosol (1.54) than for instillate (0.8). Two gamma scintigraphic methods were used to quantify dose deposited by aerosol, which permitted bioavailabilities to be determined. The bioavailable fraction for aerosolized hGH (45%) was greater than for instilled hGH (16%). This was attributed to the differential effects of mucociliary clearance. Absorption rate limited pharmacokinetics prevailed for both hGH formulations with post-peak half-lives approximately 10-fold greater than the intravenous elimination half-life of 40 min. Apparent absorption rate constants resulting from instillation and aerosolization were equivalent (0.0012 min−1and 0.0020 min−1respectively), however lung-to-blood transfer rate constants for aerosol delivery (0.00071 min −l) were greater than for instillation (0.00018 min−1).
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    URL: http://dx.doi.org/10.1023/A:1016292232513
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