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  • healthy volunteers  (37)
  • bioavailability  (28)
  • Column liquid chromatography  (26)
  • Springer  (88)
  • Alfred Wegener Institute for Polar and Marine Research & German Society of Polar Research
  • Blackwell Publishing Ltd
  • 1980-1984  (88)
  • 1950-1954
  • 1920-1924
  • 1984  (88)
Collection
Keywords
Publisher
  • Springer  (88)
  • Alfred Wegener Institute for Polar and Marine Research & German Society of Polar Research
  • Blackwell Publishing Ltd
Years
  • 1980-1984  (88)
  • 1950-1954
  • 1920-1924
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 513-520 
    ISSN: 1432-1041
    Keywords: xipamide ; electrolyte excretion ; bioavailability ; elimination ; extrarenal clearance ; chronic renal failure ; furosemide ; hydrochlorothiazide ; amiloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of a single oral dose of 40 mg xipamide on urinary excretion of Na+, K+, Cl−, Ca2+ and Mg2+ in healthy subjects and in patients with varying degrees of renal impairment was compared with various conventional diuretics. Xipamide caused marked excretion of Na+ and Cl−, whereas the diuretic produced only moderate kaliuresis; urinary excretion of Ca2+ was increased in proportion to Na+, like the loop diuretics. Xipamide affected electrolyte excretion even in patients with a creatinine clearance below 30 ml/min, as do the loop diuretics, too. Therefore, the pharmacodynamic characteristics of xipamide are more like those of a loop diuretic than of a thiazide. Xipamide was good bioavailable, its t1/2β was 7 h and urinary recovery of the undegraded drug was 40% of the given dose. In renal insufficiency, t1/2β increased from 7 to only 9 h, yielding a moderate increase in the AUC. Urinary recovery of the drug was reduced in proportion to the reduction in the creatinine clearance of the patient. Therefore, significant extrarenal elimination of the diuretic must be postulated, which suffices to prevent significant drug accumulation in renal failure.
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  • 2
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    European journal of clinical pharmacology 26 (1984), S. 627-630 
    ISSN: 1432-1041
    Keywords: bupropion ; ethanol ; pharmacokinetic interaction ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A study was performed to determine whether there is a pharmacokinetic interaction between alcohol and the novel antidepressant bupropion. In the first part 8 healthy male volunteers received single doses of 100 mg bupropion hydrochloride orally on 2 occasions accompanied by either ethanol in orange or plain orange drink according to a balanced cross over design. Plasma bupropion concentrations were determined by radioimmunoassay and kinetics analysed with the aid of NONLIN. Blood alcohol levels were assessed by breathalyser. The disposition of bupropion was adequately described by a 2 compartment model and kinetic parameters were not significantly altered by the presence of alcohol. In the second part of the study the same subjects received 40 ml ethanol in orange drink 3.5 h after ingestion of 100 mg bupropion or dummy tablet in a double blind cross over fashion. Bupropion did not affect alcohol kinetics. In contrast to many other psychotropic drugs there is no evidence for a kinetic interaction between bupropion and alcohol.
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  • 3
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    European journal of clinical pharmacology 27 (1984), S. 105-110 
    ISSN: 1432-1041
    Keywords: phenytoin ; epileptic women ; pharmacokinetics ; bioavailability ; pregnancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five epileptic women needing to commence phenytoin therapy during pregnancy received a single intravenous and a single oral dose of phenytoin several days apart before starting regular intake of the drug. Plasma phenytoin concentration — time data were analysed by three different pharmacokinetic techniques. However assessed, the mean oral bioavailability of the drug proved to be about 90% of the intravenous bioavailability. This finding makes it unlikely that impaired bioavailability accounts for the increase in oral phenytoin dosage necessary in pregnancy to maintain plasma phenytoin concentrations at pre-pregnancy values. Phenytoin clearance in the pregnant subjects was approximately double the published values for phenytoin clearance in nonpregnant persons. This suggests that increased (metabolic) clearance accounts for the increased phenytoin dosage requirement of pregnancy.
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  • 4
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    European journal of clinical pharmacology 27 (1984), S. 595-602 
    ISSN: 1432-1041
    Keywords: furosemide ; bioavailability ; generic tablet formulations ; intrasubject variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Intrasubject variation in bioavailability (rate and extent) and disposition of furosemide 40 mg was investigated using a repeated, randomized, double-blind cross-over study in 8 healthy subjects. Two generic tablet formulations (Lasix and Furix) and intravenous furosemide were compared on 6 separate days. Extensive intrasubject variability after oral administration was observed in AUC, mean absorption time (MAT) and urinary excretion. The variability (error variance) within the dosage forms was as large as that between the two generics. These variations most probably depended on the absorption process, since the repeated i.v. doses showed only marginal intrasubject variability. Absolute bioavailability was 56% for Lasix and 55% for Furix (AUC). The range was 20 to 84% between individuals and the maximal range within one individual was 20 to 61%. Confidence interval and Bayesian analysis showed a high probability of non-equivalence not only between but also within the generics when the separate cross-over experiments were analyzed (8 observations). When extending the analysis to 16 observations, bioequivalence was demonstrated for the two generic tablets. Rate of absorption, quantified as MAT, was 128 min for Lasix and 98 min for Furix (16 observations). Since MAT was significantly longer (p〈0.001) than the mean residence time after the i.v. dose (57 min), absorption was evidently the rate-limiting step in the overall kinetics of oral furosemide. Intraindividual variation in absorption is a confounding factor in bioavailability studies of furosemide using limited numbers of subjects. This is important to consider when designing and evaluating bioavailability studies for drugs showing these variations.
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  • 5
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    European journal of clinical pharmacology 26 (1984), S. 405-407 
    ISSN: 1432-1041
    Keywords: theophylline ; drug absorption ; bioavailability ; food intake ; sustained-release preparations ; Theolin Retard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of theophylline from a sustained release tablet preparation (Theolin® Retard 300 mg) was studied in 10 subjects both when fasting and immediately after a standardized breakfast. Intravenous aminophylline was used as the reference material. Food did not influence the absorption from Theolin Retard. The bioavailability was complete (93% after 30 h) both with and without food, and no difference was found in the time to peak of the plasma concentration curve (7 h), or the mean residence time (14 h). The absorption characteristics, with predominantly zero order kinetics, did not change with concomitant intake of breakfast.
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  • 6
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    European journal of clinical pharmacology 26 (1984), S. 635-637 
    ISSN: 1432-1041
    Keywords: theophylline ; inhalation ; saliva-serum distribution ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Six healthy volunteers received an iv infusion of 317 mg lysine theophylline (equivalent to 197 mg anhydrous theophylline) in order to calculate theophylline clearance by standard methods. They subsequently received a 20 minute inhalation of nebulised lysine theophylline. Serum and salivary theophylline concentrations were measured and all saliva was collected for the first hour. From these concentrations estimates were made of the distribution of theophylline into the blood and saliva with 40% to 94% identified in the blood. Very high salivary concentrations were reached during the inhalation phase with saliva: serum concentration ratios of between 60 and 1600.
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  • 7
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    European journal of clinical pharmacology 27 (1984), S. 111-114 
    ISSN: 1432-1041
    Keywords: chlorambucil ; chronic lymphocytic leukaemia ; phenylacetic acid mustard ; food intake ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of food intake on the pharmacokinetics of chlorambucil (C) and its cytotoxic metabolite, phenylacetic acid mustard (PAM), has been studied in man after oral doses of chlorambucil. The administration of chlorambucil with food resulted in slower absorption than when fasting. However, the area under the plasma concentration-time curve (AUC) was unaffected. The mean ratio AUCPAM/AUCC was 2.8 (range 1.4–7.1) under fasting and 3.3 (range 1.3–7.4) under nonfasting conditions. The metabolite very probably plays an important role in the cytotoxic effects observed after administration of C, since calculations show that a major fraction of the metabolite is eliminated by alkylation reactions.
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  • 8
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    European journal of clinical pharmacology 27 (1984), S. 115-117 
    ISSN: 1432-1041
    Keywords: benzodiazepine antagonist ; Ro 15-1788 ; healthy volunteers ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of the selective benzodiazepine antagonist Ro 15-1788 has been studied in 6 healthy male volunteers following a single intravenous dose of 2.5 mg. The drug was only slightly bound to plasma proteins (40±8%, mean±SD). A negligible amount (〈0.2% of the dose) of unchanged drug was recovered in urine. Hepatic elimination was rapid, as shown by a short t1/2 of 0.9±0.2 h, and high total plasma and blood clearances of 691±216 ml/min and 716±199 ml/min, respectively. The fast decline of plasma levels from about 60 to 2 ng/ml accounts for the short-lasting reversal of benzodiazepine-induced sedation by Ro 15-1788.
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  • 9
    ISSN: 1432-1041
    Keywords: nitroglycerin ; plasma concentration ; transdermal administration ; bioavailability ; pharmacodynamics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 6 healthy volunteers, intravenous infusions of nitroglycerin 4.8 and 10.6 µg/min yielded mean steady-state plasma concentrations of 0.5±0.02 and 0.82±0.04 ng/ml as determined by a gas chromatographic/mass spectrometric method. The plasma concentrations reached in the same subjects 17 h after application of Nitroderm TTS 5 and 10 with in vivo release rates of 3.7 and 5.7 µg/min were 0.28±0.01 and 0.37±0.01 ng/ml, respectively. Thus, 75% of the quantity of nitroglycerin released by the systems passed into the circulation. The inter-individual and intra-individual variations in plasma concentrations were similar for both modes of administration. The nitroglycerin-induced morphological changes in the fingerpulse wave were clearly dose-dependent, but it seems that this pharmacodynamic parameter is determined less by the plasma concentration than by the nitroglycerin content of the vascular wall.
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  • 10
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    European journal of clinical pharmacology 27 (1984), S. 371-373 
    ISSN: 1432-1041
    Keywords: disodium chromoglycate ; nasal airway resistance ; platelet activating factor ; healthy volunteers ; rhinomanometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Thirteen healthy subjects participated in a double blind, randomized, cross-over investigation of whether or not intranasal disodium chromoglycate could block the change in nasal airway resistance induced by platelet activating factor (PAF). Placebo or active drug was given for 3 days before intranasal challenge with PAF. Nasal airway resistance before and at intervals after callenge was determined with a rhinomanometer. Pretreatment with disodium chromoglycate blocked the decrease in nasal airway resistance induced by PAF. This indicates an alternative mode of action of disodium chromoglycate in the treatment of allergic airway diseases.
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  • 11
    ISSN: 1432-1041
    Keywords: spironolactone ; canrenone ; metabolites ; pharmacokinetics ; single/multiple oral doses ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of canrenone and ‘total metabolites’ after base hydrolysis was studied in eight young volunteers following single and multiple dose oral administration of spironolactone. The plasma levels of canrenone and ‘total metabolites’ were fitted to a two-compartment open model with a first-order absorption process. From our eight normal subjects studied, the harmonic mean of the distributive half-life (t1/2α) of canrenone was found to be 1.66 h, and the harmonic mean of the terminal elimination half-life (t1/2β) to be 22.6 h. Harmonic means of the distributive and elimination half-lives of ‘total metabolites’ after base hydrolysis were 2.48 h and 28.8 h respectively. The accumulation ratio of canrenone was 2.53, whereas that of ‘total metabolites’ was 1.89. Despite the fact that spironolactone has been shown to induce hepatic metabolism of other drugs, no evidence of autoinduction was noted in the present study, as plasma levels of canrenone and ‘total metabolites’ were found to obey a linear two-compartment model with reproducible absorption and disposition after single and multiple doses.
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  • 12
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    European journal of clinical pharmacology 27 (1984), S. 447-452 
    ISSN: 1432-1041
    Keywords: alaproclate ; antipyrine clearance ; serotonin reuptake inhibitor ; healthy volunteers ; antipyrine metabolism ; metabolite clearance ; alaproclate kinetics ; inhibition of drug metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Alaproclate, a selective serotonin reuptake inhibitor, presently undergoing clinical trial for the treatment of major depressive disorders, has been shown to inhibit hexobarbital metabolism in mice. In the present study the influence of oral alaproclate on the total plasma clearance of antipyrine and on the formation of its metabolites was investigated in 10 healthy volunteers. The peak level of alaproclate was reached after about 1.5 h, and after a distribution phase, its plasma elimination half-life was between 3.0 and 3.5 h. Antipyrine tests were performed before treatment, during the first four doses and after the seventh dose of alaproclate 200 mg/day. During treatment, total plasma antipyrine clearance and the clearance for production of all antipyrine metabolites were reduced by 30%, indicating non-selective inhibition of oxidative drug-metabolizing enzyme activity in man by alaproclate. After the last dose of alaproclate, antipyrine plasma clearance and the clearance to its metabolites returned to control values. In order to allow more detailed evaluation of the results, the time course of the clearances for production of metabolites was investigated. This revealed that the extent of inhibition of metabolite formation by alaproclate was dependent on the plasma alaproclate level, indicating a rapidly reversible inhibition.
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  • 13
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    European journal of clinical pharmacology 27 (1984), S. 471-475 
    ISSN: 1432-1041
    Keywords: acyclovir ; A515U ; 6-deoxyacyclovir ; pharmacokinetics ; prodrug ; antiviral chemotherapy ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A515U (6-deoxyacyclovir) is an analogue of acyclovir devoid of antiviral activity in vitro but which is well absorbed and undergoes conversion to acyclovir after oral administration to rats. The tolerance and pharmacokinetics of various doses of A515U have been studied in 8 healthy volunteers. Single oral doses of 25, 50, 100, 200 and 400 mg A515U and 400 mg acyclovir for comparison were administered to the volunteers at weekly intervals. Concentrations of the parent drug and acyclovir were determined in plasma and urine. The prodrug was well tolerated and did not cause adverse reactions or changes in haematological or biochemical variables. It was well absorbed and conversion to acyclovir was rapid and extensive at all doses. Plasma concentrations of acyclovir achieved with 50 mg A515U orally were comparable to and less variable than those produced by 400 mg acyclovir. A515U was rapidly cleared with a short plasma elimination half life of approximately 0.5 h. The attainment of high plasma concentrations of acyclovir by oral administration of a prodrug may represent an important advance in antiviral chemotherapy.
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  • 14
    ISSN: 1432-1041
    Keywords: benzodiazepine antagonist ; visual function ; intrinsic effect ; Ro 15-1788 ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ro 15-1788 is a specific benzodiazepine antagonist, which has also been shown to have some agonist properties. Since benzodiazepine receptors are involved in the physiological mechanisms of vision, a possible intrinsic effect of Ro 15-1788 was sought in 6 healthy volunteers by study of psychophysical flicker thresholds, including critical fusion frequency and low frequency modulation threshold, and pattern reversal visual evoked response, using double blind cross-over methodology. In each session 2 tablets of Ro 15-1788 30 mg were administered. Using a two factorial univariate analysis of variancé, no change was detected in any of the parameters studied.
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  • 15
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    European journal of clinical pharmacology 27 (1984), S. 535-538 
    ISSN: 1432-1041
    Keywords: pindolol ; healthy volunteers ; heart rate ; intrinsic sympathomimetic activity ; diurnal heart rate ; nocturnal heart rate ; rebound effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect on heart rate of pindolol 5, 15 and 30 mg/day, a beta-adrenoreceptor blocker possessing intrinsic sympathomimetic activity, administered to 8 healthy volunteers for 14 days was studied. Heart rate was continuously recorded over 24 h during placebo treatment before each sequence, every 2 days during treatment, and then on the 15th, 17th and 18th days. Pindolol in the three doses used had no significant effect on mean heart rate over 24 h. It tended to lower mean diurnal heart rate non-significantly between noon and 6 p.m. Pindolol raised nocturnal heart rate between midnight and 6 a.m. to a comparable extent at all the doses used. Sympathetic tone is at its lowest during that period, which makes it possible to detect the intrinsic sympathomimetic activity of pindolol. After cessation of treatment, a rebound effect was observed, cardioacceleration being most marked after 30 mg/day.
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  • 16
    ISSN: 1432-1041
    Keywords: zetidoline ; prolactin ; aldosterone ; dopamine ; healthy volunteers ; pharmacodynamic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The neuroendocrinological effects of acute oral administration of 20 mg zetidoline, a new antipsychotic drug with antidopaminergic properties, were evaluated in 8 healthy volunteers, by a double-blind, crossover comparison with placebo. Zetidoline significantly increased serum prolactin (p〈0.01 at 1–3 h; p〈0.05 at 4–6 h). No significant change was observed in blood levels of aldosterone, renin, cortisol, growth hormone and electrolytes, or in blood pressure and heart rate. The data suggest that the drug increases prolactin through blockade of dopaminergic receptors. The lack of change in the aldosterone levels may be evidence against the hypothesis of dopaminergic control of aldosterone secretion.
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  • 17
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    European journal of clinical pharmacology 26 (1984), S. 133-135 
    ISSN: 1432-1041
    Keywords: co-dergocrine mesylate ; geriatric patients ; hydergine ; bioavailability ; steady state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The relative bioavailability of the newly developed formulation of co-dergocrine mesylate (Hydergine spezial, 1×4 mg) was determined in elderly patients under steady state conditions, with conventional Hydergine forte tablets (2×2 mg) as a reference. Both formulations were given once a day for 8 days in a randomised cross-over design. The areas under the curve showed that the bioavailability of the new tablet was about 30% higher (28±6.3%) than that of Hydergine forte. The peak plasma concentration was reached 3±0.9 h after administration. Because of its greater relative bioavailability higher plasma levels were found 2–24 hours after the Hydergine spezial formulation than after Hydergine forte tablets.
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  • 18
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    European journal of clinical pharmacology 26 (1984), S. 261-264 
    ISSN: 1432-1041
    Keywords: indomethacin capsules ; bioequivalence ; volunteers ; pharmacokinetics ; statistical significance ; bioavailability ; comparative bioequivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Two, separate 6×6 Latin square cross-over bioequivalence studies were performed in adult male volunteers using 10 different indomethacin capsule preparations marketed in India together with the pure drug powder as the standard. The products were evaluated with respect to plasma level at various times up to 8 h following administration of a 50 mg (2 × 25 mg) dose. Plasma samples were analysed by a fluorimetric method. Various pharmacokinetic parameters were calculated according to a two compartment model. Statistical evaluation of the data employed analysis of variance for a cross-over design (ANOVA) and Duncan's multiple range test to ascertain the significance of differences between the products. Of the 10 products studied, two were found to be bioinequivalent.
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  • 19
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    European journal of clinical pharmacology 26 (1984), S. 463-470 
    ISSN: 1432-1041
    Keywords: dihydroergotamine ; 8′-hydroxy-dihydroergotamine ; plasma metabolites ; bioavailability ; receptor affinity ; healthy volunteers ; liver microsomal incubates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma concentrations and urinary excretion of dihydroergotamine and its metabolites have been measured after a single oral administration of 3 mg tritium-labelled drug to 6 male volunteers. The plasma level of non-volatile radioactivity declined biphasically with α- and β-phase half-lives of 2.1 h and 32.3 h, respectively. The peak plasma concentration was reached within 3.2h. Urinary excretion of total non-volatile radioactivity was low, amounting to 1.0% of the dose. The parent drug and four metabolites could be quantitated in urine and plasma samples. Metabolite 4 (8′-hydroxy-dihydroergotamine) was isolated from incubates of rat and monkey liver microsomal preparations. In human liver microsomal incubates, metabolite 4 was shown to be the primary metabolite of dihydroergotamine. In receptor binding studies performed with mammalian brain preparations, metabolite 4 had IC50-values at 6 monoaminergic binding sites similar to those of dihydroergotamine. Thus, it appears that the active principle consists at least of dihydroergotamine and its 8′-hydroxy derivative. As the concentration of metabolite 4 exceeded 5–7 times that of dihydroergotamine in urine and plasma, the bioavailability of dihydroergotamine should be reevaluated, taking into account the plasma concentrations of the parent drug and of its acitve metabolite, 8′-hydroxydihydroergotamine.
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  • 20
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    European journal of clinical pharmacology 26 (1984), S. 533-534 
    ISSN: 1432-1041
    Keywords: amiodarone ; bioavailability ; clearance estimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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  • 21
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    European journal of clinical pharmacology 27 (1984), S. 191-196 
    ISSN: 1432-1041
    Keywords: pizotifen 5-hydroxyindoleacetic acid ; homovanillic acid ; urinary excretion ; healthy volunteers ; migraine prevention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A single dose of 0.5 mg pizotifen or a placebo was administered to 10 healthy male volunteers in a double blind cross-over trial. 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in hourly urine samples were determined by liquid chromatography with amperometric detection. The 5-HIAA levels were strongly correlated with the HVA levels in control samples (r=0.95, p〈0.001). Pizotifen produced a significant increase in the urinary 5-HIAA/HVA ratio over the 3 hours following absorption of the drug (+0.21, +0.18, +0.19, p〈0.05). The increase demonstrates an interaction between pizotifen and 5-HT metabolism, which may be involved in its antimigraine effect.
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  • 22
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    European journal of clinical pharmacology 27 (1984), S. 483-489 
    ISSN: 1432-1041
    Keywords: radiosensitiser ; pharmacokinetics ; healthy volunteers ; tumour patients ; Ro 03-8799
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A new hypoxic cell radiosensitiser, Ro 03-8799 has been administered intravenously to human volunteers and its kinetic parameters derived from plasma and urine data. Good penetration of drug into tumour tissue is found, consistent with its large volume of distribution. The plasma clearance of this compound is rapid due to high metabolic and renal clearances. These parameters combine to produce an elimination half-life of 5.6 h, approximately half that of misonidazole, a well studied radiosensitiser. It is hoped that this decrease in total body exposure will also reduce the cumulative toxicity seen when misonidazole is administered repeatedly.
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  • 23
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    European journal of clinical pharmacology 27 (1984), S. 501-503 
    ISSN: 1432-1041
    Keywords: valpromide ; valproic acid ; pharmacokinetics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of valpromide, a primary amide of valproic acid, was investigated in 6 healthy, adult male volunteers, each of whom was given 900 mg as a marketed, enteric-coated tablet and a solution. Valpromide was biotransformed to valproic acid after the administration of the tablet and the solution with a bioavailability of 0.79±0.24 and 0.77±0.12, respectively, relative to a marketed tablet of valproic acid. The absorption of valpromide was not rate-limited by dissolution. As a solid, non-hygroscopic, neutral prodrug of valproic acid, valpromide may be a good alternative to valproic acid and sodium valproate.
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  • 24
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    European journal of clinical pharmacology 26 (1984), S. 125-127 
    ISSN: 1432-1041
    Keywords: nadolol ; pharmacokinetics ; plasma levels ; urinary excretion ; bioavailability ; circadian rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 7 healthy subjects (3 males and 4 females), the kinetics of nadolol was investigated after oral doses of 60 and 120 mg. The t1/2 was 14.0±1.8 h. The peak plasma level was doubled on doubling the dose (from 69±15 to 132±27 ng/ml, respectively) and the urinary excretion (13.5%) rose similarly. The half-life of elimination was longer at night than in the day, probably because of the slower nocturnal flow of urine.
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  • 25
    ISSN: 1432-1041
    Keywords: cimetidine ; cystic fibrosis ; bioavailability ; renal clearance ; renal function differences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and metabolism of cimetidine were studied in five cystic fibrosis patients (mean age 12.6 years) after oral and intravenous administration. As compared to healthy adult volunteers, cystic fibrosis children had an elevated cimetidine total body clearance (474 vs 300 ml/min/m2) as well as renal clearance (293 vs 232 ml/min/m2) whether normalized for body weight or surface area differences. Cimetidine elimination was elevated in juvenile cystic fibrosis patients as compared to adult volunteers, however, it did not differ significantly from that previously seen in age matched children. There were no appreciable differences in cimetidine metabolism after either route of administration. Differences between adults and cystic fibrosis children were attributed to developmental and age related differences between the two groups. The recommended pediatric dose of 15 to 20 mg/kg, although four-fold greater than that used in adults, produces serum concentrations similar to those seen in adults, and is adequate for most juvenile cystic fibrosis patients.
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  • 26
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    European journal of clinical pharmacology 26 (1984), S. 197-207 
    ISSN: 1432-1041
    Keywords: furosemide ; bioavailability ; pharmacokinetics ; oral administration ; i.v. administration ; drug absorption ; moment analysis ; food effect ; dissolution effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Furosemide 40 mg was administered to 8 healthy subjects as an i.v. bolus dose, as 1 tablet in the fasting state, and as 1 tablet and a solution after food intake. The i.v. data gave a total body clearance of 162±10.8 ml/min and a renal clearance of 117±11.3 ml/min; the volume of distribution at steady state was 8.3±0.61. Oral administration gave a bioavailability of the tablet (fasting) of 51%. Food intake slightly reduced the bioavailability, but not to a significant extent. There was no significant difference in availability between the tablet and the solution. Moment analysis gave a mean residence time after the i.v. dose, MRTi.v., of 51±1.5 min. The mean absorption times (MAT) for all oral doses were significantly longer than the MRTi.v., indicating absorption rate-limited kinetics of furosemide. On average, food delayed the absorption by 60 min. The MAT for the tablet in the postprandial state was significantly longer than for the solution, indicating dissolution rate-limited absorption of the tablet.
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  • 27
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    European journal of clinical pharmacology 26 (1984), S. 271-273 
    ISSN: 1432-1041
    Keywords: cimetidine ; prednisolone ; aluminium phosphate ; antacids ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ten fasting subjects received 200 mg cimetidine orally either with water or 11 g aluminium phosphate mixture in a randomized, single dose, two-way cross-over study. Blood samples were taken for 12 h and urine was collected for 24 h. Cimetidine in plasma and urine was analysed by HPLC. There were no significant differences between the treatments with respect to peak plasma concentration, time to peak plasma concentration, area under the plasma concentration-time curve, and urinary excretion. In 12 healthy subjects the absorption of prednisolone was investigated when given alone and together with 11 g aluminium phosphate. Blood samples were taken over 16 h and prednisolone in plasma was analysed by HPLC. There were no significant differences in the values of area under curve (AUC), Cmax and tmax. The results indicate that aluminium phosphate does not reduce the bioavailability of cimetidine and prednisolone.
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  • 28
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    European journal of clinical pharmacology 26 (1984), S. 347-355 
    ISSN: 1432-1041
    Keywords: cimetidine ; cirrhosis ; pharmacokinetics ; bioavailability ; clearance reduction
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of impaired liver function on the pharmacokinetics of cimetidine was studied in 8 patients with advanced cirrhosis given single doses of 100 mg i.v. and 400 mg p.o. on separate days. Compared to a control group of 10 healthy volunteers, the total renal and nonrenal clearance was significantly reduced in the cirrhotic patients; (total plasma clearance mean ± SD) 356±181 vs 789±262 ml/min (p〈0.01); renal clearance (Clr) 296±100 vs 588±181 ml/min (p〈0.01) and nonrenal clearance (Clnr) 97±111 vs 205±89 ml/min (p〈0.05). Compared to published results for age-matched ulcer patients, both total and nonrenal clearance were lower whereas renal clearance was within the reported normal range. A significant reduction in volume of distribution (Vdβ) was found, from 2.1±0.1 l/kg in controls to 1.0±0.4l/kg, and in the patient group there was a significant correlation between Vdβ and total plasma clearance (r=0.72, p〈0.05). Volume of distribution in steady state (Vdss) did not differ from published results in age-matched controls. No significant change in half-life was found. Bioavailability, estimated by AUC-measurement, showed considerable patient variability (21–143%), with a mean of 70±39%. This was lower than in the controls. In contrast, measurement of urinary excretion showed higher bioavailability in the patients (66±23 vs 51±8%). No correlation was found between any of the kinetic parameters and the clinical and laboratory data. It is suggested that patients with advanced cirrhosis should be closely observed when given cimetidine, and a reduction in dose should be concidered if side effects are to be avoided.
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  • 29
    ISSN: 1432-1041
    Keywords: trimethoprim ; concentration ; urinary excretion ; healthy volunteers ; steady state ; pharmacokinetics ; serum creatinine
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The steady state pharmacokinetics of trimethoprim was determined after 300 mg orally once daily to 6 healty volunteers for 9 days. The microbiological assay of plasma level was unreliable at trimethoprim concentrations 〉4 µg/ml, so results from an HPLC-assay are given. Steady state was present after 3 days. The plasma concentration peaked 1 to 4 h (mean 2.0 h) after the dose at a mean of 6.0 µg/ml (range 3.1–9.5 µg/ml); the minimum value was 1.5 µg/ml (range 0.6–2.9 µg/ml). The mean AUCss was 77 µg/ml · h and the mean plasma clearancess was 67 and 74 ml/min on Days 8 and 9. Renal clearance was about 60% of the plasma clearance. The average plasma half life was 10.6 h (range 8.7–15.3 h). Thus, there was considerable interindividual variation in all pharmacokinetic parameters. 72 h after the last dose trimethoprim was detectable in plasma in only 1 of the 6 subjects. The minimum urinary concentration of trimethoprim during treatment was always well above (range 22 to 220 µg/ml) the MIC values for most urinary tract pathogens. Therefore, a daily dose of 300 mg trimethoprim results in a therapeutic concentration in urine at steady state that lasts throughout the dosing interval and in most subjects probably lasts also for a further 24 h. Trimethoprim administration raised mean serum creatinine from 67 to 97 µmol/l, probably due to competitive inhibition of the tubular secretion of creatinine.
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  • 30
    ISSN: 1432-1041
    Keywords: acetylsalicylic acid ; platelet function ; salicylate ; controlled release formulation ; single dosing ; continuous dosing ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The extent to which a controlled release acetylsalicylic acid (ASA) formulation inhibited platelet function has been evaluated in single and chronic dosing studies. In the single dose study, the platelet inhibitory effect of the controlled release formulation was compared with that of an equivalent dose of soluble ASA and an equimolar dose of sodium salicylate (SA). In the chronic dosing study, ASA dose-response curves for platelet function, including cyclooxygenase activity, were determined for various doses (20–1300 mg) of the controlled release (enteric coated pellets) ASA formulation taken by volunteers daily for one week. Platelet function was assessed by the degree of inhibition of aggregation for several aggregating agents, and the degree of inhibition of activity of platelet cyclooxygenase quantified by the estimation of malondialdehyde (MDA) production. Plasma ASA and SA concentrations were also determined in each study. The controlled release product inhibited platelet function to the same extent as an equimolar dose of soluble ASA, but did so with much lower and sometimes undetectable peak systemic plasma ASA concentrations. SA, the direct metabolite of aspirin, did not have any effect on platelet function. The ASA dose-platelet function response curves obtained from chronic dosing with the controlled release formulation appeared to be similar to those reported previously for the soluble product. The inhibition of platelet function appeared to be unrelated to plasma ASA concentrations.
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  • 31
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    European journal of clinical pharmacology 27 (1984), S. 105-110 
    ISSN: 1432-1041
    Keywords: phenytoin ; epileptic women ; pharmacokinetics ; bioavailability ; pregnancy
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five epileptic women needing to commence phenytoin therapy during pregnancy received a single intravenous and a single oral dose of phenytoin several days apart before starting regular intake of the drug. Plasma phenytoin concentration — time data were analysed by three different pharmacokinetic techniques. However assessed, the mean oral bioavailability of the drug proved to be about 90% of the intravenous bioavailability. This finding makes it unlikely that impaired bioavailability accounts for the increase in oral phenytoin dosage necessary in pregnancy to maintain plasma phenytoin concentrations at pre-pregnancy values. Phenytoin clearance in the pregnant subjects was approximately double the published values for phenytoin clearance in nonpregnant persons. This suggests that increased (metabolic) clearance accounts for the increased phenytoin dosage requirement of pregnancy.
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  • 32
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    European journal of clinical pharmacology 27 (1984), S. 23-27 
    ISSN: 1432-1041
    Keywords: hypertension ; alpha2-adrenoceptors ; blood pressure ; clonidine ; guanfacine ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The time courses of the changes in plasma growth hormone and noradrenaline concentrations in response to 15 min infusions of clonidine 0.2 mgs and guanfacine 2 mgs, were studied in six normal volunteers, in a double-blind, randomised, crossover study. Plasma noradrenaline fell within 15 min of the commencement of drug administration, by 36±14% after clonidine (p〈0.05) and by 32±11% (p〈0.05) after guanfacine. Plasma growth hormone was not significantly elevated until the 30th minute to 12.0±4.7 lU/ml (p〈0.05) after clonidine and 14.7±11.5 lU/ml (p〈0.05) after guanfacine, having been undetectable prior to both drugs. The reduction in plasma noradrenaline by these α2-adrenergic agonists, prior to activation of central adrenoceptors as detected by changes in plasma growth hormone, is evidence for a peripheral component in their sympatholytic effect.
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  • 33
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    European journal of clinical pharmacology 27 (1984), S. 75-80 
    ISSN: 1432-1041
    Keywords: bupropion ; alcohol interaction ; healthy volunteers ; performance ; autonomic functions
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of bupropion and ethanol were examined alone and in combination in a placebo controlled, double-blind, crossover study in 12 healthy volunteers. Results were subjected to analysis of variance and differences ofp〈0.05 taken as significant. In the main study using the Wilkinson auditory vigilance test, no active treatment or combination of treatments produced significant change compared with placebo. However, when compared with bupropion 100 mg, vigilance was significantly impaired by 32 ml alcohol alone though not when combined with bupropion. No significant changes in reaction time or short term memory occurred. Visual analogue scales indicated that the subjects were mentally slower after alcohol 32 ml than after placebo. Combination of bupropion 100 mg with alcohol 32 ml abolished this difference. A similar pattern occurred with group ratings indicating mental sedation. Subjects were clearly able to differentiate between the 16 ml and 32 ml doses of alcohol when assessing their degree of inebriation. Combination of bupropion with alcohol made no difference to the ratings of inebriation. The top dose of alcohol tended to increase energy in the low frequency EEG bands. Combination of the top alcohol dose with bupropion, however, produced a significant reversal with lowered energy in the 4–7.5 Hz band. Combination of bupropion with alcohol failed to change the blood alcohol concentration achieved.
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  • 34
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    European journal of clinical pharmacology 27 (1984), S. 111-114 
    ISSN: 1432-1041
    Keywords: chlorambucil ; chronic lymphocytic leukaemia ; phenylacetic acid mustard ; food intake ; pharmacokinetics ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of food intake on the pharmacokinetics of chlorambucil (C) and its cytotoxic metabolite, phenylacetic acid mustard (PAM), has been studied in man after oral doses of chlorambucil. The administration of chlorambucil with food resulted in slower absorption than when fasting. However, the area under the plasma concentration-time curve (AUC) was unaffected. The mean ratio AUCPAM/AUCC was 2.8 (range 1.4–7.1) under fasting and 3.3 (range 1.3–7.4) under nonfasting conditions. The metabolite very probably plays an important role in the cytotoxic effects observed after administration of C, since calculations show that a major fraction of the metabolite is eliminated by alkylation reactions.
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  • 35
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    European journal of clinical pharmacology 27 (1984), S. 119-121 
    ISSN: 1432-1041
    Keywords: S-adenosyl-L-methionine ; pharmacokinetics ; protein binding ; dose-dependent kinetics ; healthy volunteers ; urinary excretion
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary S-Adenosyl-L-methionine (AdoMet) kinetics was studied in 6 male subjects given 100 and 500 mg i. v. Drug concentrations in plasma and urine were assayed using a radioenzymatic method. Pharmacokinetic parameters were estimated according to an open two-compartment model. The apparent volumes of distribution after the 100 and 500 mg doses were 407±27 and 443±36 ml/kg (mean±SEM), terminal half-lives 81±8 and 101±7 min and body clearances 3.7±0.5 and 3.1±0.2 ml/min per kg. Urinary excretion was 34±3 and 40±2% of the administered dose. The results demonstrate that drug disposition occurs more via metabolism than via renal excretion, and it is not dependent on the administered dose. Binding of AdoMet to serum proteins is negligible.
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  • 36
    ISSN: 1432-1041
    Keywords: nitroglycerin ; plasma concentration ; transdermal administration ; bioavailability ; pharmacodynamics ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 6 healthy volunteers, intravenous infusions of nitroglycerin 4.8 and 10.6 µg/min yielded mean steady-state plasma concentrations of 0.5±0.02 and 0.82±0.04 ng/ml as determined by a gas chromatographic/mass spectrometric method. The plasma concentrations reached in the same subjects 17 h after application of Nitroderm TTS 5 and 10 with in vivo release rates of 3.7 and 5.7 µg/min were 0.28±0.01 and 0.37±0.01 ng/ml, respectively. Thus, 75% of the quantity of nitroglycerin released by the systems passed into the circulation. The inter-individual and intra-individual variations in plasma concentrations were similar for both modes of administration. The nitroglycerin-induced morphological changes in the fingerpulse wave were clearly dose-dependent, but it seems that this pharmacodynamic parameter is determined less by the plasma concentration than by the nitroglycerin content of the vascular wall.
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  • 37
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    European journal of clinical pharmacology 27 (1984), S. 367-369 
    ISSN: 1432-1041
    Keywords: flurbiprofen ; syrup ; suppository ; kinetics ; children ; bioavailability
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Eight subjects, aged 6–12 years and weighing 18.8–36.7 kg, received single doses of flurbiprofen 50 or 75 mg (corresponding to 1.4–2.7 mg/kg) as syrup and suppository in a Latin square design. Half-life (2.7–3.2 h), elimination constant (0.22–0.26 h−1), area under the plasma level curve (72.4–77.3 µg·h·ml−1) and time to reach the concentration peak (1–0.75 h) were similar after the syrup and suppository. Flurbiprofen showed equivalent bioavailability after oral and rectal administration and the same pharmacokinetic profile was confirmed in children as observed in adults.
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  • 38
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    European journal of clinical pharmacology 27 (1984), S. 453-458 
    ISSN: 1432-1041
    Keywords: dipyrone ; metabolism ; metabolite pharmacokinetics ; acetylation polymorphism ; healthy volunteers ; dapsone phenotyping
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of the dipyrone metabolites 4-methylaminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylaminoantipyrine (AAA) were evaluated following the administration of a single oral 1.0 g dose of dipyrone to 23 healthy volunteers. Twelve were slow and 11 were rapid acetylators as previously determined by dapsone phenotyping. For MAA and FAA the mean peak plasma concentrations were 10.5±2.8 µg/ml and 2.1±0.8 µg/ml and the half-lives were 3.3±1.0 and 10.1±1.8 h, respectively. No significant difference was found between rapid and slow acetylators in MAA and FAA kinetics. For AA, the mean peak plasma concentrations were 2.7±0.6 and 1.6±0.7 µg/ml (p〈0.01), the peak times 6.7±2.1 and 3.1±1.1 h (p〈0.01) and the half-lives were 5.5±1.0 and 3.8±1.2 h in slow and rapid acetylators, respectively. For AAA, the mean peak plasma concentrations were 1.6±0.4 and 4.4±1.1 µg/ml (p〈0.01) and the peak time 16.1±5.1 and 10.0±2.6 h (p〈0.01) in slow and rapid acetylators, respectively. There was no difference in the elimination half-life between the two groups (10.6±2.2 h). Thus, it has been demonstrated that the AAA/AA ratio is an indicator of the acetylation phenotype, as it is closely correlated with that determined by dapsone (r=0.895, p〈0.0005).
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  • 39
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    European journal of clinical pharmacology 27 (1984), S. 495-497 
    ISSN: 1432-1041
    Keywords: ranitidine ; aldosterone secretion ; sodium depletion ; drug interference ; plasma renin activity ; biochemical parameters ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of a 3-day oral course of ranitidine on plasma aldosterone level has been studied in 6 normotensive volunteers maintained in a state of sodium depletion. A significant fall in plasma aldosterone (p〈0.05–0.02), in both the overnight recumbency levels and in the levels obtained during a two hour period of ambulation was observed. The change took place in the absence of variation in plasma renin activity and potassium. Plasma cortisol and prolactin levels were lower after ranitidine at the beginning of the test but their values were not significantly different after ambulation during ranitidine therapy. Ranitidine appears to interfere with aldosterone secretion in vivo.
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  • 40
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    European journal of clinical pharmacology 27 (1984), S. 623-624 
    ISSN: 1432-1041
    Keywords: cimetidine ; bioavailability ; renal clearance
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    Topics: Chemistry and Pharmacology , Medicine
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  • 41
    ISSN: 1432-1041
    Keywords: cimotaxone ; MAO inhibitor ; plasma prolactin ; circadian rhythm ; healthy volunteers ; hypothalamic MAO ; prolactin secretion ; metabolism ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Prolactin (PRL) secretion is stimulated by serotonin (5-HT) and inhibited by dopamine (DA). 5-HT is generally recognized as a substrate for type A monoamine oxidase (MAO), whereas DA is considered as a substrate for either A or B, or both forms of MAO, depending on the species and tissues used. The effect of cimoxatone, a reversible, selective MAO-A inhibitor, on diurnal variation in plasma PRL level was investigated in healthy adults after a single 40 mg oral dose, as an indirect approach to investigating whether DA is preferentially a substrate for Type A or B MAO in man. The circadian rhythm in PRL, stress conditions and diet were taken into account in the present study, which was placebo-controlled. There was a slight but significant reduction in circulating PRL in the six subjects, which persisted for at least 9 h after cimoxatone. However, the duration of the decrease in plasma PRL was shorter than the inhibition of MAO-A. The results are not inconsistent with the presence of both forms of MAO in the human hypothalamus and with DA as a substrate for both forms in this region, if it is assumed that the hypothalamic concentrations of the drug during the period 0–9 hours was sufficiently high to inhibit DA deamination by both forms of MAO.
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  • 42
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    European journal of clinical pharmacology 26 (1984), S. 129-131 
    ISSN: 1432-1041
    Keywords: aprindine ; antiarrhythmic agent ; healthy volunteers ; plasma level ; oral administration ; pharmacokinetics ; urinary excretion
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The disposition of aprindine following a single oral dose can best be described by a two-compartment open model. The mean plasma half-life (t1/2β) increased from 8.0±2.1 h (SD) after a 25 mg dose to 9.4±2.9 h after 50 mg and to 15.8±2.6 h after 100 mg, with a decrease in total plasma clearance (Cl/F) and volume of distribution at steady state (Vdss/F) and during β-phase (Vdβ/F). The area under plasma concentration-time curve (AUC), maximum plasma concentration (Cmax) and the amount of unchanged aprindine excreted in the urine increased in a non-linear fashion with the increase in dose. The t1/2β after multiple oral doses showed a 3-fold increase over the single dose value. These results indicate that aprindine shows dose-dependent non-linear kinetics.
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  • 43
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    European journal of clinical pharmacology 26 (1984), S. 269-270 
    ISSN: 1432-1041
    Keywords: cyclophosphamide ; cytostatic drug ; cancer therapy ; female breast cancer ; bioavailability ; rapid release formulations ; gastric juice resistant formulation ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Cyclophosphamide (CP) is an alkylating cytostatic compound, which is activated to its cytotoxic form in the liver [1]. Since the therapeutic range of CP in the treatment of human tumours, is small like other cytostatics, a constant high bioavailability is essential for its oral administration. Although CP has become one of the most widely used cytostatics [2], there do not appear to have been any bioavailability investigations providing the necessary information. The development of a very sensitive gas chromatographic analytical method has now permited investigation of the pharmacokinetics of oral CP in conventional clinical doses [3, 4, 5, 6].
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  • 44
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    European journal of clinical pharmacology 26 (1984), S. 603-608 
    ISSN: 1432-1041
    Keywords: pinacidil ; hypertension ; pinacidil pyridine-N-oxide ; urinary excretion ; protein binding ; pharmacokinetics ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Preliminary investigation in 3 healthy volunteers suggested that intravenous pinacidil in a dose of 0.2 mg/kg had a potent but well-tolerated hypotensive action in the supine position. Facial flushing, uncomfortable chest sensation and distressing postural hypotension occurred at serum concentrations above 300 ng/ml. Pinacidil, 0.2 mg/kg, was given intravenously over 4 min to 15 healthy volunteers in the supine position. Maximum fall in mean arterial pressure (MAP) was 15.7±6.0 mmHg. Maximum rise in heart rate was 23.8±6.6 beats/min. Pinacidil serum distribution half-life ( $${\text{T}}_{{\raise0.7ex\hbox{${\text{1}}$} \!\mathord{\left/ {\vphantom {{\text{1}} {{\text{2}}\alpha }}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${{\text{2}}\alpha }$}}}$$ ) was 13.4±8.5 min and elimination half-life ( $${\text{T}}_{{\raise0.7ex\hbox{${\text{1}}$} \!\mathord{\left/ {\vphantom {{\text{1}} {{\text{2}}\beta }}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${{\text{2}}\beta }$}}}$$ ) was 2.13±0.49 h. The apparent volume of distribution (Vdβ) was 90.3±13.21 and total body clearance was 31.1±9.61/h. Pinacidil was approximately 40% bound to plasma protein over the concentration range 40–400 ng/ml. Urinary excretion of unchanged pinacidil accounted for 5.7 ± 1.3% of the administered dose over 24 hours and urinary excretion of the major metabolite, pinacidil pyridine-N-oxide, was 31.6±9.2% of the administered dose. It was concluded that intravenous pinacidil is a potent vasodilator hypotensive compound, with a duration of action between 1.5 and 2 h.
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  • 45
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    European journal of clinical pharmacology 26 (1984), S. 761-767 
    ISSN: 1432-1041
    Keywords: drug absorption ; intoxication ; activated charcoal ; disopyramide ; indomethacin ; trimethoprim ; healthy volunteers ; adsorption capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The efficacy of various charcoal-to-drug ratios for the absorption of drugs was studied in 6 healthy volunteers and in vitro at two pHs. Disopyramide 200 mg, indomethacin 50 mg and trimethoprim 200 mg were ingested on an empty stomach with 100 ml water. After 5 min the subjects ingested a charcoal suspension in 300 ml — 2.5 g, 10 g, 25 g or 50 g of Norit A, or 10 g of PX-21, or water 300 ml only. Increasing the dose of activated charcoal from 2.5 g to 50 g reduced the gastrointestinal absorption of disopyramide and indomethacin from 30–40% to 3–5%, and that of trimethoprim from 10% to 1% of the respective controls. Disopyramide and trimethoprim were best adsorbed by charcoal in vitro at neutral and indomethacin at acid pH, but saturation of the adsorption capacity was apparent at charcoal-to-drug ratios less than 7.5. Combining the in vitro and in vivo results it can be concluded that the dose of activated charcoal to be given in acute intoxication should be as large as possible, because the drug history is often unknown.
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  • 46
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    European journal of clinical pharmacology 27 (1984), S. 75-80 
    ISSN: 1432-1041
    Keywords: bupropion ; alcohol interaction ; healthy volunteers ; performance ; autonomic functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of bupropion and ethanol were examined alone and in combination in a placebo controlled, double-blind, crossover study in 12 healthy volunteers. Results were subjected to analysis of variance and differences ofp〈0.05 taken as significant. In the main study using the Wilkinson auditory vigilance test, no active treatment or combination of treatments produced significant change compared with placebo. However, when compared with bupropion 100 mg, vigilance was significantly impaired by 32 ml alcohol alone though not when combined with bupropion. No significant changes in reaction time or short term memory occurred. Visual analogue scales indicated that the subjects were mentally slower after alcohol 32 ml than after placebo. Combination of bupropion 100 mg with alcohol 32 ml abolished this difference. A similar pattern occurred with group ratings indicating mental sedation. Subjects were clearly able to differentiate between the 16 ml and 32 ml doses of alcohol when assessing their degree of inebriation. Combination of bupropion with alcohol made no difference to the ratings of inebriation. The top dose of alcohol tended to increase energy in the low frequency EEG bands. Combination of the top alcohol dose with bupropion, however, produced a significant reversal with lowered energy in the 4–7.5 Hz band. Combination of bupropion with alcohol failed to change the blood alcohol concentration achieved.
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  • 47
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    European journal of clinical pharmacology 27 (1984), S. 85-89 
    ISSN: 1432-1041
    Keywords: digitoxin ; radioimmunoassay ; pharmacokinetics ; bioavailability ; digitoxin metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of digitoxin were examined in six normal human subjects using an assay that separates digitoxin from its metabolites. After intravenous administration, the mean systemic clearance was 2.44 ml/min; the volume of distribution was 0.47 l/kg; and the elimination half-life was 6.5 days. After oral administration, the elimination half-life was 5.8 days. The bioavailability was 81.5% using the specific assay. Using a non-specific, direct serum digitoxin radioimmunoassay the bioavailability was 98.0%. Assay of aqueous fractions from extracted serum samples indicated higher levels of water-soluble metabolites following oral compared to intravenous digitoxin administration. These findings suggest that previously reported values for digitoxin bioavailability using non-specific methods may be falsely elevated due to the presence of digitoxin metabolites in serum.
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  • 48
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    European journal of clinical pharmacology 27 (1984), S. 23-27 
    ISSN: 1432-1041
    Keywords: hypertension ; alpha2-adrenoceptors ; blood pressure ; clonidine ; guanfacine ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The time courses of the changes in plasma growth hormone and noradrenaline concentrations in response to 15 min infusions of clonidine 0.2 mgs and guanfacine 2 mgs, were studied in six normal volunteers, in a double-blind, randomised, crossover study. Plasma noradrenaline fell within 15 min of the commencement of drug administration, by 36±14% after clonidine (p〈0.05) and by 32±11% (p〈0.05) after guanfacine. Plasma growth hormone was not significantly elevated until the 30th minute to 12.0±4.7 lU/ml (p〈0.05) after clonidine and 14.7±11.5 lU/ml (p〈0.05) after guanfacine, having been undetectable prior to both drugs. The reduction in plasma noradrenaline by these α2-adrenergic agonists, prior to activation of central adrenoceptors as detected by changes in plasma growth hormone, is evidence for a peripheral component in their sympatholytic effect.
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  • 49
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    European journal of clinical pharmacology 27 (1984), S. 85-89 
    ISSN: 1432-1041
    Keywords: digitoxin ; radioimmunoassay ; pharmacokinetics ; bioavailability ; digitoxin metabolites
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of digitoxin were examined in six normal human subjects using an assay that separates digitoxin from its metabolites. After intravenous administration, the mean systemic clearance was 2.44 ml/min; the volume of distribution was 0.47 l/kg; and the elimination half-life was 6.5 days. After oral administration, the elimination half-life was 5.8 days. The bioavailability was 81.5% using the specific assay. Using a non-specific, direct serum digitoxin radioimmunoassay the bioavailability was 98.0%. Assay of aqueous fractions from extracted serum samples indicated higher levels of water-soluble metabolites following oral compared to intravenous digitoxin administration. These findings suggest that previously reported values for digitoxin bioavailability using non-specific methods may be falsely elevated due to the presence of digitoxin metabolites in serum.
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  • 50
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    European journal of clinical pharmacology 27 (1984), S. 119-121 
    ISSN: 1432-1041
    Keywords: S-adenosyl-L-methionine ; pharmacokinetics ; protein binding ; dose-dependent kinetics ; healthy volunteers ; urinary excretion
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary S-Adenosyl-L-methionine (AdoMet) kinetics was studied in 6 male subjects given 100 and 500 mg i. v. Drug concentrations in plasma and urine were assayed using a radioenzymatic method. Pharmacokinetic parameters were estimated according to an open two-compartment model. The apparent volumes of distribution after the 100 and 500 mg doses were 407±27 and 443±36 ml/kg (mean±SEM), terminal half-lives 81±8 and 101±7 min and body clearances 3.7±0.5 and 3.1±0.2 ml/min per kg. Urinary excretion was 34±3 and 40±2% of the administered dose. The results demonstrate that drug disposition occurs more via metabolism than via renal excretion, and it is not dependent on the administered dose. Binding of AdoMet to serum proteins is negligible.
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  • 51
    ISSN: 1432-1041
    Keywords: acetylsalicylic acid ; platelet function ; salicylate ; controlled release formulation ; single dosing ; continuous dosing ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The extent to which a controlled release acetylsalicylic acid (ASA) formulation inhibited platelet function has been evaluated in single and chronic dosing studies. In the single dose study, the platelet inhibitory effect of the controlled release formulation was compared with that of an equivalent dose of soluble ASA and an equimolar dose of sodium salicylate (SA). In the chronic dosing study, ASA dose-response curves for platelet function, including cyclooxygenase activity, were determined for various doses (20–1300 mg) of the controlled release (enteric coated pellets) ASA formulation taken by volunteers daily for one week. Platelet function was assessed by the degree of inhibition of aggregation for several aggregating agents, and the degree of inhibition of activity of platelet cyclooxygenase quantified by the estimation of malondialdehyde (MDA) production. Plasma ASA and SA concentrations were also determined in each study. The controlled release product inhibited platelet function to the same extent as an equimolar dose of soluble ASA, but did so with much lower and sometimes undetectable peak systemic plasma ASA concentrations. SA, the direct metabolite of aspirin, did not have any effect on platelet function. The ASA dose-platelet function response curves obtained from chronic dosing with the controlled release formulation appeared to be similar to those reported previously for the soluble product. The inhibition of platelet function appeared to be unrelated to plasma ASA concentrations.
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  • 52
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    European journal of clinical pharmacology 27 (1984), S. 115-117 
    ISSN: 1432-1041
    Keywords: benzodiazepine antagonist ; Ro 15-1788 ; healthy volunteers ; pharmacokinetics
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of the selective benzodiazepine antagonist Ro 15-1788 has been studied in 6 healthy male volunteers following a single intravenous dose of 2.5 mg. The drug was only slightly bound to plasma proteins (40±8%, mean±SD). A negligible amount (〈0.2% of the dose) of unchanged drug was recovered in urine. Hepatic elimination was rapid, as shown by a short t1/2 of 0.9±0.2 h, and high total plasma and blood clearances of 691±216 ml/min and 716±199 ml/min, respectively. The fast decline of plasma levels from about 60 to 2 ng/ml accounts for the short-lasting reversal of benzodiazepine-induced sedation by Ro 15-1788.
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  • 53
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    European journal of clinical pharmacology 27 (1984), S. 335-339 
    ISSN: 1432-1041
    Keywords: transdihydrolisuride ; dopamine agonist ; pharmacokinetics ; pharmacodynamics ; prolactin levels ; side-effects ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma levels and urinary excretion of the dopamine agonist, transdihydrolisuride (TDHL), were measured by radioimmunoassay in healthy male volunteers given TDHL 50 µg i.v. and oral doses of 200, 400 and 800 µg. Plasma prolactin was also measured by radioimmunoassay. Following i.v. injection, the concentration of TDHL declined with a half-life of 37±19 min. The total clearance was 38±27 ml/min/kg and the apparent volume of distribution was 1.3±0.4 l/kg. The bioavailability of oral TDHL was proportional to the dose; after 200, 400 and 800 µg the bioavailability was 20±25%, 31±24% and 48±26%. TDHL was almost totally metabolized and less than 0.5% of the dose was excreted unchanged in urine in 24 h. Plasma prolactin levels were depressed by 66±15%, 75±11% and 80±7% after TDHL 200 µg, 400 µg and 800 µg. The effect lasted for more than 12 h after the lowest dose and for more than 24 h after 400 and 800 µg. Side effects, mainly nausea and headache, only occurred at the two highest dose levels.
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  • 54
    ISSN: 1432-1041
    Keywords: molsidomine ; vasodilators ; pharmacokinetics ; pharmacodynamics ; dose-response relationship ; haemodynamics ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 12 healthy male volunteers, molsidomine 1, 2 and 4 mg i.v. increased resting heart rate and decreased systolic blood pressure, the latter still being affected after 8 hours. After single oral doses of 1 and 2 mg, systolic pressure tended to be reduced for 90 minutes and exercise heart rate tended to be increased. After oral treatment with 2 mg molsidomine three times daily for 1 week, the pharmacokinetic parameters and the effects on heart rate and blood pressure after the final dose were not different from those after the first dose. The terminal half-life was independent of dose and route of administration. Clearance and distribution volume were not dose-dependent. The bioavailability of a 2 mg oral dose of molsidomine was 44%. Inter-individual variation in heart rate, blood pressure and pharmacokinetics was observed.
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  • 55
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    European journal of clinical pharmacology 27 (1984), S. 303-306 
    ISSN: 1432-1041
    Keywords: frusemide ; renal function ; ageing ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of IV frusemide was studied in six healthy young (mean age 26.5 years, range 21–33) and six healthy old (mean age 72.8 years, range 66–80) volunteers. A 24-h urine collection before frusemide showed no difference in volume and sodium excretion, although the old excreted less potassium. Creatinine clearance was significantly reduced in the older subjects. After frusemide, 20 mg IV, the pattern of sodium and water excretion over a 5-h period was different in the two groups. The peak effect was greater in the young and occurred within the first 30 min, but was delayed to between 30 and 60 min in the old. Thus in the young the time for 50% of the total sodium and water to be excreted was half that in the old. This delay in sodium and water excretion was related to baseline creatinine clearance. However, the total water, sodium and potassium excreted in the 5 h after frusemide did not differ in the two groups. These results suggest that the renal effects of frusemide are different in healthy elderly subjects as compared to the young. The delayed and reduced peak response is consistent with fewer nephrons in the elderly kidney.
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  • 56
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    European journal of clinical pharmacology 27 (1984), S. 319-324 
    ISSN: 1432-1041
    Keywords: theophylline ; enprofylline ; terbutaline ; haemodynamic response ; adenosine antagonism ; healthy volunteers
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The haemodynamic response to two xanthines, enprofylline and theophylline, was studied in 6 healthy male volunteers at rest, during exercise and in combination with the beta2-agonist, terbutaline. At rest the haemodynamic effects of both xanthines were small and were qualitatively different from each other. While theophylline exerted a “pressor” response, enprofylline seemed to have arterial dilating ability. During exercise both xanthines as compared to placebo were associated with a higher heart rate and in general with increased systolic blood pressure. In combination with terbutaline enprofylline and theophylline both increased systolic blood pressure more than placebo, i. e. they augmented the positive inotropic effect of terbutaline. The systolic blood pressure was higher after theophylline than enprofylline despite their equipotent bronchodilator activity. This may reflect different inotropic effects of the xanthines as well as a difference in their influence on the response to adenosine.
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  • 57
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    European journal of clinical pharmacology 27 (1984), S. 325-328 
    ISSN: 1432-1041
    Keywords: theophylline ; sustained release ; pharmacokinetics ; chronic administration ; healthy volunteers ; plasma levels ; GCMS assay ; stable isotope technique
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of a new sustained-release preparation of theophylline (Dilatrane à Action Prolongée capsules filled with homogenous microgranules) has been after its studied administration to 7 healthy volunteers at 8 p.m. in order to achieve therapeutic levels at night and in the morning. In separate trials the test dose of 500 or 600 mg was administered for 7 days, once daily at 8 p.m. Plasma theophylline levels were measured by capillary gas chromatography with a mass specific detector after pentylation, using internal standards labelled with stable isotopes (15N-1,3 and 13C-2 theophylline). The new sustained-release preparation showed a monophasic regular absorption phase with very low interindividual variability. After administration, the plasma level stayed within 80% of the peak levels for 8.5±1.5 h. There was a good correlation between the dose and the steady state plasma level (r=0.9587; p〈0.05). This preparation can be chronically administered once daily day at 8 p.m. in order to achieve a therapeutic level during the night and the morning, and to provide sufficient protection during the nycterohemeral period, with a once dose a day schedule.
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  • 58
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aromatic acid isomers ; Low capacity ion-exchange resin ; Microbore packed columns
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    Topics: Chemistry and Pharmacology
    Notes: Summary A low-capacity, anion-exchange, porous-polymer resin was used as the packing material in a microbore column. Using a phosphate buffer containing various organic modifiers, retention behavior of substituted benzoic acid isomers with amino, chloro, methyl, nitro and carboxylic groups was investigated. The effect of ethanol, acetonitrile and sodium dodecylsulfate used as organic modifiers on the retention behavior at various eluent pH values was studies and optimum separations of the positional isomers reported.
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  • 59
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    Chromatographia 18 (1984), S. 668-672 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mixed eluents ; Preferential sorption of eluents ; Pressure effects
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    Topics: Chemistry and Pharmacology
    Notes: Summary Pronounced base line perturbations were repeatably observed in LC both in alternating recycling and in backflushing experiments when binary eluents and refractometric detectors were used. The perturbations which we call eigenzones appeared immediately after operating the recycling or the backflushing valve, and their size and shape depended on the nature of both the column filling and the mixed mobile phase as well as on the pressure drop across the column. Experimental results presented confirm that the primary causes of the eigenzones were the pressure changes in the columns which influenced the sorption equilibrium of mixed eluent components within the column packing. Some practical consequences of this effect are briefly discussed.
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  • 60
    ISSN: 1612-1112
    Keywords: Polycyclic aromatic hydrocarbons ; Column liquid chromatography ; Polyphenyl bonded phases ; Retention and carbon content
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    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the retention of PAHs having various molecular sizes and the carbon contents (%) of bonded stationary phases with various types of ligands were investigated. The examined stationary phases were phenyl, diphenyl, triphenyl and benzyl-bonded silicas. The data indicated that sometimes it is not true that the retention of any solute relates linearly to the carbon content of the stationary phase. As the result, it is suggested that the pore size distribution of the silica support, the bulkiness of the ligand bonded to the silica and the molecular size of solute should also be considered before any precise statement can be made.
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  • 61
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    Chromatographia 18 (1984), S. 175-182 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fourier transform IR ; Polar compounds ; Coal products
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    Topics: Chemistry and Pharmacology
    Notes: Summary Fourier-transform infrared spectrometry (FTIR) was utilized as a detection system for high-performance liquid chromatography of polar compounds on a normal bonded-phase system. In addition to FTIR, UV (254 nm) and refractive index detection were employed in the separation of model compounds containing oxygen and nitrogen atoms in their molecules (phenols, alcohols, neutral and weakly basic nitrogen compounds). A polar amino-cyano (PAC) bonded-phase column was employed with a binary mobile phase (98:2 CDCl3:CH3CN). The separations and the information gained from each detector is discussed, including interactions between sample material and mobile phase. A polar fraction of a coal-derived product is also chromatographed under identical conditions. The results based on FTIR detection and chromatographic retention behavior suggest the exclusive presence of hindered and unhindered phenols.
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  • 62
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    Chromatographia 18 (1984), S. 211-215 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkylbenzenes ; PAHs ; Retention prediction ; Microcomputer
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    Topics: Chemistry and Pharmacology
    Notes: Summary The microcomputer-assisted retention prediction system in C18 reversed-phase HPLC is described. The system is based on the use of the hydrophobic parameter and the correlation factor of alkylbenzenes and polycyclic aromatic hydrocarbons (PAHs) which are highly correlated to their retention in reversed-phase HPLC. The system is evaluated by comparing the retention data between measured and predicted values. One of the typical examples applied for PAH analysis in the extracts of diesel particulate matter shows the high potential of the system investigated.
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  • 63
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    Chromatographia 18 (1984), S. 216-220 
    ISSN: 1612-1112
    Keywords: Cation exchangers ; Column liquid chromatography ; Exchange capacity, determination ; Organic peroxidation
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    Topics: Chemistry and Pharmacology
    Notes: Summary Two oxidation procedures for the synthesis of silicabased aliphatic sulfonic acid cation-exchangers for HPLC are described. Several reaction conditions for oxidizing a terminal-bonded thiol with organic peroxides are provided along with their yields, capacities, reproducibility, and chromatographic behavior. Also, three methods for determining exchange capacity are discussed, and their relationship to the capacity factors of charged solutes is compared. The maximum capacity determined by the titration of the bonded silica was 0.34 meq/gram. The general problems of synthesizing cation-exchangers, measuring their efficiencies and exchange capacities, and evaluating their overall performances are outlined.
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  • 64
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    Chromatographia 18 (1984), S. 369-373 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange ; dynamic ; Metal ions ; Equilibria effects
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    Topics: Chemistry and Pharmacology
    Notes: Summary Equilibria occurring during the dynamic ion exchange separation of metal ions were examined, and their effect on the chromatography of the metal ions was evaluated. Bonded reversed-phase silica, pure organic reversed phase, and silica columns were used to differentiate between the role of silica and the reverse phase. The results show that system peaks had the most important influence on the applicability of dynamic exchangers to quantitative metal ion determinations. The response of system peaks to sample composition (pH, ionic strength, matrix effects) was complicated and could not be predicted easily. Equilibria effects that can cause analytical errors were identified and recommendations for elimination of such errors are given.
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  • 65
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amines ; Phenols ; Fourier transform I.R.
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    Topics: Chemistry and Pharmacology
    Notes: Summary Several chromatographic parameters have been examined as to their effect on detectability for microbore high-performance liquid chromatography coupled with Fourier-transform infrared spectrometry. Detection limits for several compound classes are presented as amount injected. Improvements in detectability for this technique are discussed.
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  • 66
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polystyrene packings ; Pre-column derivatization ; Thiamine compounds ; UV and fluorescence detection
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    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatography of thiochrome and related phosphate esters was studied on two different polystyrene packing materials. The adsorbents were compared with respect to capacity factors, plate heights and resolution factors measured with different mixtures of phosphate buffer (pH 8.5) and methanol. In contrast with derivatized silica, these phases were found to be stable using an alkaline mobile phase and sample. Fast separations were possible with good peak symmetry at all organic modifier concentrations.
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  • 67
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    Chromatographia 18 (1984), S. 445-448 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino-bonded stationary phase ; Ion-exchange ; Fermentation solution ; Biomass
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    Topics: Chemistry and Pharmacology
    Notes: Summary In this work the analytical separation of biomass hydrolysis and fermentation products is described. Aminobonded phase and ion exchange materials (HPX 87H, HPX 42A, μ Spherogel Carbohydrate) were used as HPLC stationary phases for the determination of monomeric and oligomeric carbohydrates, carbohydrate degradation and fermentation products. The HPX 42A and the amino-bonded phase columns are especially suitable for the analysis of the gluco oligomers. The HPX 87H column separates the monomeric sugars and their degradation and fermentation products (e.g. furfurals and ethanol) very well. Using the μ Spherogel Carbohydrate column the lower gluco-oligomers as well as the monomeric sugars and their degradation and fermentation products, can be determined within 35 minutes.
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  • 68
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral bonded phase ; Racemate resolution
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    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral stationary phase with an immobilized, optically active diamine was prepared for the separation of enantiomers. The synthesis of the phase was carried out by bonding (−)trans-1,2-cyclohexanediamine to microparticulate silica gel through the coupling agent 3-glycidoxypropylsilane. The resolution of the racemic compounds catechin, 2,2′-dihydroxy-1,1′binaphthyl and trans-1,2-cyclohexandiol, is reported.
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  • 69
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    Chromatographia 18 (1984), S. 495-498 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; PAHs ; Molecular shape recognition
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    Topics: Chemistry and Pharmacology
    Notes: Summary The molecular-shape recognition of polycyclic aromatic hydrocarbons has been studied on various stationary phases in reversed-phase high-performance liquid chromatography. The examined stationary phases were phenyl-, diphenyl-, triphenyl- and benzyl-bonded silicas. The results of regression analysis inidcated that triphenylsilica is the best packing material to recognize the difference in the molecular-shape of structural isomers. This fact was confirmed by the separation of 4-ring isomers.
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  • 70
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention data ; Substituted benzene derivatives ; Correlations
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    Topics: Chemistry and Pharmacology
    Notes: Summary The capacity factors of substituted benzene derivatives on bonded phases of various chain lengths in the reversed-phase mode have been measured and correlation of retention data between four stationary phases has been investigated by linear regression analysis. As a result, a difference in the retention mechanism between phases of shorter chain length and octadecylsilica was observed. In addition, it is also apparent that the multicombination treatment between retention data and descriptors such as π, HA, HD and σ promises the possibility of predicting the retention of substituted benzene derivatives on various reversed-phase stationary phases.
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  • 71
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyamines ; Dansyl derivatives ; Peak compression
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    Topics: Chemistry and Pharmacology
    Notes: Summary Analytical conditions for the high-speed, reversed-phase, liquid chromatographic of a diamine (putrescine) and polyamines (spermine and spermidine) were determined. Various elution modes were employed using the same mobile phase constituents: 20mM sodium heptane sulfonate and 20mM acetic acid as solvent A and, pure acetonitrile as solvent B. Samples were derivatized with dansyl chloride before injection. Under isocratic conditions, the separation of the three polyamines was achieved in 7 min. The use of a linear elution gradient led to the same analytical time but with a better resolution of the putrescine peak from non-polyamine frontal peaks. For these measurements, the sample size was 5μl. This volume was increased to 20μl and the use of a steep gradient combined with the peak-compression technique allowed a fast analysis in 2–3 minutes, which may be compared with a 30 min run time necessary when a conventional column is used.
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  • 72
    ISSN: 1573-8744
    Keywords: hydrochlorothiazide ; triamterene ; hydroxytriamterene sulfate ; pharmacokinetics ; bioavailability ; renal clearance ; interaction
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate were monitored in the plasma and urine of 24 healthy young men taking single doses of a liquid preparation containing both hydrochlorothiazide and triameterene, liquid preparations containing either of these drugs alone, and a combination tablet recently formulated with a dose ratio of hydrochlorothiazide: triamterene (1∶1,5) found to give optimal potassium-sparing effect. In contradiction to a recent publication, no interaction between the drugs affecting the bioavailability or renal clearance of either could be demonstrated. The previous report of drug-drug interaction probably arose from formulationrelated problems with bioavailability from the two capsule and two tablet products which had been studied. A well-formulated hydrochlorothiazide-triamterene combination tablet promotes plasma concentrations and urinary excretion of hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate which are virtually identical to those seen after either a combination liquid dosage form or simple liquid forms containing only one of the two drugs.
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  • 73
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    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 289-313 
    ISSN: 1573-8744
    Keywords: protein binding ; pharmacokinetics ; bioavailability ; disopyramide ; heart failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and bioavailability of total (bound plus unbound) and unbound disopyramide were compared following the simultaneous administration of an oral dose of disopyramide and an intravenous dose of14C-disopyramide in five normal volunteers and in 11 patients with congestive heart failure. The binding of disopyramide varied between 60 and 92% in patients and between 81 and 88% in normal subjects at postequilibrium drug concentrations of 10−7M. The binding of disopyramide to serum protein was concentration-dependent in all study subjects at serum concentrations achieved following drug administration. The association constant for the first binding site in serum from normal subjects and patients averaged 8.7X105 M−1 and 4.4X10 5 M−1, respectively (p 〈 0.05). The unbound clearance of disopyramide averaged 277ml/min and 209 ml/min in normal subjects and in patients (p 〈 0.05). When normalized for body weight, the unbound clearance between patients and normal subjects was not significantly different. The elimination half-life of unbound concentrations in normal subjects and in patients averaged 4.9 and 6.1 h, respectively (p 〈 0.05). The clearance and elimination half-life of total disopyramide was the same in both groups. Although the bioavailability of disopyramide averaged 0.85 in both groups, it was more variable in patients owing to the variability in the fraction of the dose absorbed. The unbound renal clearance and volume of distribution at steady state of disopyramide was related to cardiac index. The ratio of elimination half-lives of total and unbound disopyramide was related to the extent of serum protein binding.
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  • 74
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    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 315-331 
    ISSN: 1573-8744
    Keywords: theophylline ; antacids ; interaction ; bioavailability ; steady state
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    Topics: Chemistry and Pharmacology
    Notes: Abstract We examined the influence of a large-volume, therapeutic antacid regimen, administered for three full days, on the steady-state bioavailability of a conventional-release and sustained-release theophylline product, Aminophyllin and Theodur, respectively. Nine stable asthmatics voluntarily completed a four-phase investigation requiring a total stay of 12 days in the Clinical Research Unit. The treatments consisted of administration of the formulations mentioned with and without antacids to each patient in a randomized sequence. Four patients participated in an additional phase where antacids were administered q2h around the clock for three days. After coadministration of theophylline plus antacids for two days, theophylline therapy was discontinued while numerous blood samples were obtained over 22 hr and analyzed for theophylline content via radioimmunoassay. Antacids had no predictable, consistent influence on theophylline absorption rate as determined by the absorption rate constant, the time to maximal theophylline concentration, or the lag time for theophylline absorption. Antacids had no detectable influence on theophylline elimination half-life and had no consistent, statistically significant effect on the extent of theophylline bioavailability, according to measurements of maximal concentration, AUCmeasured over the appropriate steady-state dosing interval, or elimination-rate adjusted AUC.The substantial intraindividual changes for all parameters of theophylline bioavailability that occurred for control and treatment phases likely represent spontaneous, random between-day variability in theophylline disposition independent of antacid administration, as evidenced by the comparability of the percent coefficient of variation for parameters of biovailability across all phases. Our data demonstrate that therapeutic antacid administration has no effect on steady-state theophylline bioavailability and does not alter the intrinsic variability in theophylline absorption. Based on the results of our data, it is unlikely that a clinically significant (〉20%) decrease in theophylline absorption would occur in any patient treated intensively with antacids concurrently.
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    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 83-91 
    ISSN: 1573-8744
    Keywords: bioavailability ; bioequivalence ; hypothesis tests ; sample size determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The clinical problem of testing for equivalence in comparative bioavailability trials is restated in terms of the proper statistical hypotheses. A simple t-test procedure for these hypotheses has been devloped that is more powerful than the methods based on usual (shortest) and symmetric confidence intervals. In this note, this new procedure is explained and an example is given, including the method for sample size determination.
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  • 76
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    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 437-450 
    ISSN: 1573-8744
    Keywords: first-pass ; bioavailability ; Michaelis-Menten ; volume of distribution ; absorption rate constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two approaches used for bioavailability determination of drugs with Michaelis-Menten elimination kinetics were examined by computer simulation. The first method involved treating the drug as though its clearance remained constant during elimination, and the conventional method of taking the ratio of areas under the curve resulting from the oral and intravenous doses was used to calculate bioavailability. The second approach involved using the Michaelis parameters, Vmax and Km,to determine concentration dependent clearance values, but based these calculations on peripheral drug concentrations rather than on concentrations entering or in the liver. We have developed a simulation method that was used to test the accuracy of the above two methods. In the simulations described, Vmax, Km,and hepatic blood flow were chosen to represent a drug with an extraction ratio of 0.9 under linear conditions, but with Michaelis-Menten kinetics occurring at the doses given. Absorption was assumed to be first-order, and metabolism was assumed to occur only in the liver. These simulations showed that the most accurate determination of bioavailability requires knowledge of the direct contribution of oral absorption to the concentration of drug entering the liver. Unexpectedly, the results also showed that if a drug has a large volume of distribution or a large absorption rate constant, or both, use of the much simpler conventional method of bioavailability determination may be appropriate even in cases where the degree of saturation is substantial.
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  • 77
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    Chromatographia 18 (1984), S. 574-578 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore column ; Flow rate stability ; Performance ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Some quantitative implications of the use of microbore columns in column liquid chromatography are investigated. Although for several pumps the flow rate stability at 50 μl min−1 is slightly worse than that of pumps operating at 1 ml min−1, the quantitative performance with respect to repeatability and reproducibility of response factors equals that of conventional liquid chromatography. Thermostatting is strongly recommended for microbore column operation.
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  • 78
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    Chromatographia 18 (1984), S. 62-64 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Microparticulate packing ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A procedure is described by which 20 commonly occurring amino acids may be separated by reversed-phase liquid chromatography at room temperature in a total time, including derivatisation with o-phthalaldehyde/2-mercaptoethanol reagent, of approximately 15 minutes. Further, an increase in column temperature enables increased resolution of certain amino acids to be obtained with small but acceptable losses in fluorescence intensity. The only major drawback to the method is that the derivatisation reagent does not react with proline or hydroxyproline.
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  • 79
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    Chromatographia 18 (1984), S. 15-17 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair ; Dynamic equillibrium ; Aqueous and aqueous alcohol eluents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This work describes the dynamic equilibrium of an ionpair, reverse-phase liquid chromatography system. A given adsorbed quantity of an anionic surfactant can lead to different capacity factors and selectivity for anionic solutes.
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  • 80
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention correlation ; Silica ; Normal and reversed phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The correlation between the retention data of polyaromatic hydrocarbons (PAH) obtained in normal-and reversed-phase liquid chromatography is investigated in order to determine the dominant factors controlling the retention. It is clear that the separation of PAHs on various chemically-bonded packing materials in normal- and/or reversed-phase modes is primarily controlled by the molecular structure and shape. The π-electron interaction between the solute and the stationary phase also contributes to the retention, although pure silica shows a somewhat different behavior.
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  • 81
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    Chromatographia 18 (1984), S. 600-602 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sugars ; Copper (II) complex ; UV detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive method of sugar analysis by HPLC is described in which a copper (II) modified silica gel as stationary phase is used. Detection is based on UV absorption of a complex formed between the sugar, copper, and ammonia.
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  • 82
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    Chromatographia 18 (1984), S. 695-697 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Semi-microbore columns ; Reverse-phase ; 3 μm packing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation and use of semi-microbore (2mm i.d.), reverse-phase columns in HPLC has been investigated and they have been compared with 5 mm bore analytical columns. Injection valve design, detector cell volume, column loading and column linking are considered for both semi-microbore and analytical systems. Mobile phase flow-rate, detector time constant and column lifetime are also evaluated for small-bore systems.
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  • 83
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Quantitative determination of L-alanine ; DABS-Cl ; Tryglycine sulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the quantitative determination of L-alanine in triglycine sulphate crystals, in the presence of excess amounts of glycine, is described. L-alanine is determined after derivatization with 4-N,N-dimethyl-aminoazobenzene-4′-sulfonyl chloride (DABS-Cl) and in the presence of DABS-valine used as the internal standard. The results obtained indicate that the method permits the determination of alanine in triglycine sulphate crystals at concentrations of about 1%.
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  • 84
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    Chromatographia 18 (1984), S. 73-80 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore columns ; Performance ; High-speed separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microbore columns of 1 mm i.d. have turned out to be very suitable for the achievement of efficient columns. The packing procedure for stainless steel 1 mm i.d. columns from 5 to 100 cm in length was studied. Stationary phases used were: pure silica gel, octyl, octadecyl and amino bonded silicas. The main parameters (slurry composition, packing system, choice of materials) are discussed. Short columns packed with 3 or 5μm particles allow high speed separations. A separation in 18 seconds is described. Very high plate numbers can be obtained with long columns. With 7–8μm particles, a 1 m column can produce 50,000 plates (h=3). Columns can be joined without loss of efficiency. 270 000 theoretical plates were obtained on a 6 m adsorption column with a test mixture. In reversed-phase chromatography, bile acid sodium salts can be separated on a 1 m column. In adsorption chromatography, details are given of the separation of a polystyrene oligomer sample, as well as a light and a heavy petroleum distillate samples on a 2 m column with refractive index detection in the last-case.
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  • 85
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    Chromatographia 18 (1984), S. 84-86 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Stationary phase evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the evaluation of reversed phase packing materials a mixture of acetylacetone, I-nitronaphthalene and naphthalene is proposed. This will reveal the usual optimum kinetic chromatographic parameters (the naphthalene peak), the degree of activity or endcapping status of the column (the ratio of the I-nitronaphthalene and naphthalene retention times) and trace metal activity (the shape and intensity of the acetylacetone peak).
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  • 86
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    Chromatographia 18 (1984), S. 81-83 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded phases ; Characterisation ; Toxicological screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes a test (“DMD-test”) to determine chromatographic properties of C8- or C18-bonded phases. The test was developed to select HPLC columns, for clinical and forensic toxicological screening in particular. The three compounds for the DMD-test are: diphenhydramine, 5-(p-methylphenyl)-5-phenylhydantoin (=MPPH) and diazepam. The isocratic mobile phase (acetonitrile/buffer pH2.3) is suitable for analysis of biological samples. 24 commercially available columns were tested. From our work this test enables the selection of commercial HPLC columns with reproducible properties. In this way a reference LC retention list can be developed to identify analytical results on an inter- or intralaboratory basis.
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    Chromatographia 18 (1984), S. 90-95 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Retention prediction ; Substituted benzenes ; Molecular parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of substituted benzene derivaties on a reversed-phase C-18 column has been examined. The correlations between the logarithm of the capacity factor and several descriptors indicating the molecular size, shape and the physical properties of a solute were determined. The results indicated that hydrophobicity is the dominant factor to control the retention of substituted benzenes. Their retention in reversed-phase HPLC can be predicted with help of the equations derived by multicombination of the parameters.
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  • 88
    ISSN: 1612-1112
    Keywords: Aldehydes and ketones ; 2,4-dinitrophenylhydrazine-coated silica gel ; Gas chromatography ; Column liquid chromatography ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary After a brief review of several methods described in the literature this paper discusses air-sampling on 2,4-dinitrophenylhydrazine-coated silica gel and identification requirements for aldehydes and ketones most commonly found in industrial pollution. Quantitative analysis of formaldehyde and acetaldehyde either by GC or by HPLC techniques is established using a dynamic system producing test atmospheres and compared with the usual colorimetric determinations.
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