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  • 101
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1975), S. 169-178 
    ISSN: 1432-1041
    Schlagwort(e): Heptabarbital ; heptabarbital sodium ; pharmacokinetics ; plasma concentration ; single and multiple dose kinetics ; relative bioavailability ; urinary excretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A method has been developed for the quantitative determination of heptabarbital [5-(1-cyclohepten-1-yl)-5-ethylbarbituric acid] in human plasma after administration of single therapeutic doses of the drug. It involves a single extraction step followed by gas chromatography with alkali flame ionization detection, and the results were linear in the concentration range 0.125 – 5.0 µg/ml plasma. The pharmacokinetics and relative bioavailability of heptabarbital and heptabarbital sodium were studied in a crossover design in 7 healthy volunteers after oral administration of 20 tablets containing 200 mg heptabarbital and hard gelatine capsules containing an equivalent amount of its sodium salt. Heptabarbital concentrations in plasma were determined at regular intervals. The absorption of heptabarbital from the tablets was quite slow and peak level times varied from 1.5 to 4 h. The sodium salt was absorbed more rapidly and peak concentrations occurred between 1/3 and 2 h. In all cases the elimination of heptabarbital could be described by a single first-order process with an average half-life of 7.6 h (range 6.1 – 11.2 h). The half-life of the drug in each individual was about the same in the two trials. The relative bioavailability in each volunteer was estimated by comparing the areas under the plasma concentration curves. The sodium salt had an average bioavailability of 83% relative to the free acid. In some volunteers urinary excretion of unchanged heptabarbital was measured; cumulative excretion amounted to 0.16 – 0.30% of the administered dose. Four volunteers received one tablet each night for eight or ten days, but no accumulation was found. In three volunteers the half-life of the drug prior to and after these experiments did not change, whereas in the other volunteer the half-life decreased from 7.1 to 4.6 h. The possibility of enzyme induction should be considered when heptabarbital is taken regularly. It was concluded that heptabarbital was a suitable drug for the treatment of insomnia, since its half-life was rather short. Heptabarbital sodium may be used for induction of sleep, whereas Medomin® tablets, i.e. heptabarbital free acid, may be prescribed when the maintenance of sleep is the primary reason for treatment with a hypnotic drug.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1975), S. 199-207 
    ISSN: 1432-1041
    Schlagwort(e): Indomethacin ; acetylsalicylic acid ; drug interaction ; oral and rectal dosing ; serum levels ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A clinical-pharmacological study was performed to determine the effect of acetylsalicylic acid upon the serum concentration of indomethacin. 14 rheumatic patients were given indomethacin orally (25 mg × 4 for 4 days) and concurrently acetylsalicylic acid 3.7 g orally (0.9 g × 3 and 1.0 g × 1 daily), and 21 rheumatic patients were given indomethacin rectally in the morning (100 mg × 1) and concurrently acetylsalicylic acid 3.7 g orally (0.9 g × 3 and 1.0 g × 1 daily). On comparison with treatment with oral or rectal indomethacin alone, it was found that peak serum concentrations of indomethacin were significantly reduced (1% level), the times of the peaks were not shifted, and the areas beneath the serum concentration curves of indomethacin were smaller, but significantly so only if compared with rectal administration. In 12 rheumatic patients given indomethacin by rectum in the evening (100 mg × 1) and concurrently acetylsalicylic acid 3.7 g (0.9 g × 3 and 1.0 g × 1 daily), the serum level of indomethacin on the following morning (after 11 h) did not differ from that found after rectal treatment. A statistically but not biologically significant difference was observed between the mean serum half-lives of indomethacin given orally and rectally. For unknown reasons, concurrent doses of acetylsalicylic acid and indomethacin made the mean serum half-life of indomethacin longer than after its oral administration, but shorter than when the same dose of indomethacin was given rectally. There was no difference between serum levels of salicylate after oral administration of acetylsalicylic acid alone or after a concurrent oral or rectal dose of indomethacin. The results have been related to those reported previously, with respect to the interaction between indomethacin and acetylsalicylic acid, the serum levels of indomethacin after oral and rectal dosing, and the serum half-life of indomethacin based upon a one- or two-compartment model. The clinical relevance of the study is discussed.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1975), S. 229-234 
    ISSN: 1432-1041
    Schlagwort(e): Quercetin ; flavonoids ; pharmacokinetics ; absorption ; disposition ; metabolism ; man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of quercetin, a flavonoid, have been studied in 6 volunteers after single intravenous (100 mg) and oral (4 g) doses. The data after iv administration were analyzed according to a two compartment open model with half lives of 8.8±1.2 min for the α phase and 2.4±0.2 h for the β phase (predominant half life), respectively. Protein binding was 〉98%. The apparent volume of distribution was small at 0.34±0.03 l/kg. Of the intravenous dose 7.4±1.2% was excreted in urine as a conjugated metabolite, and 0.65±0.1% was excreted unchanged. After oral administration no measurable plasma concentrations could be detected, nor was any quercetin found in urine, either unchanged or in a metabolized form. These results exclude absorption of more than 1% of unchanged drug. Recovery in faeces after the oral dose was 53±5%, which suggests extensive degradation by microorganisms in the gut. The data obtained show that oral administration of flavonoids may be of questionable value.
    Materialart: Digitale Medien
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  • 104
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1976), S. 327-332 
    ISSN: 1432-1041
    Schlagwort(e): Antipyrine ; pharmacokinetics ; half-life ; blood ; plasma ; saliva ; individual variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A previously described GLC method has been modified and applied to measurement of antipyrine levels in plasma, blood and saliva of man following administration of a single oral dose (10 mg/kg). The levels in blood and saliva were comparable to those in plasma at every time studied. The half life of antipyrine determined in blood, plasma or saliva in any given individual was similar. The intersubject variation in half-life was about two-fold (n=5). Antipyrine levels in saliva were not affected by the rate of saliva flow when collections were made continuously for 20 minutes. This study has demonstrated that kinetic data about antipyrine comparable to that from plasma may also be obtained from readily accessible tissue fluids, such as saliva and capillary blood.
    Materialart: Digitale Medien
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  • 105
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1976), S. 319-325 
    ISSN: 1432-1041
    Schlagwort(e): Chlorthalidone ; diuretics ; drug plasma concentration ; protein binding ; red blood-cell concentration ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A gas chromatographic method has been employed to determine chlorthalidone in plasma and whole blood after therapeutic doses. Radioactively labelled chlorthalidone was used for in vitro studies of the uptake of chlorthalidone from plasma by red blood cells. Chlorthalidone was markedly concentrated in red cells and as a compartment they would account for at least 30% of total drug in the body after multiple doses. The ratio between the plasma and red cell concentration of chlorthalidone varied between individuals. After a single oral dose of 50 mg in 6 healthy volunteers chlorthalidone was eliminated with a half-life of 51 to 89 hours. The apparent volume of distribution varied between 3 and 13 1/kg and the clearance between 53 and 145 ml/min. The mean steady-state plasma concentrations during treatment with a standard dose of 50 mg daily (n=10) varied 5-fold between individuals. During the steady state approximately 50% of the daily dose was excreted unchanged in the urine during 24 hrs. The plasma levels observed in patients were higher than those predicted from the single oral dose studies in healthy volunteers.
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  • 106
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1976), S. 367-372 
    ISSN: 1432-1041
    Schlagwort(e): Sotalol ; β-adrenoceptor blocking drugs ; exercise tachycardia ; efficacy ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effects of sotalol after oral administration were measured on the tachycardia induced by strenuous exercise in normal subjects. Plasma sotalol levels were also determined. The oral administration of sotalol (50, 100, 200 and 400 mg) to 6 subjects produced a progressive reduction in the tachycardia induced by severe exercise. This was similar to the effects of 25, 50, 100, 200, 400 and 800 mg given to different subjects. Each increase in sotalol dose produced a successively greater reduction in exercise tachycardia. This did not appear to be maximum even with 800 mg. Oral sotalol was rapidly absorbed and produced peak blood levels in 2 – 3 hours. The plasma levels of sotalol measured 2 hours after the oral administration of 25 to 800 mg showed never more than a six-fold variation between different subjects. The half-life of sotalol in plasma was 12.7 ± SE 1.6 hours. There was a significant correlation between the logarithm of the plasma sotalol concentration and the percentage reduction of exercise heart rate. It is concluded that the oral administration of sotalol either once or twice daily (depending on dose level) will provide satisfactory 24-hour blockade of β-adrenoceptors.
    Materialart: Digitale Medien
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  • 107
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 9 (1976), S. 443-450 
    ISSN: 1432-1041
    Schlagwort(e): Cyclobarbital calcium ; pharmacokinetics ; plasma concentration ; relative bioavailability ; oral administration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics and relative bioavailability of cyclobarbital calcium have been studied after oral administration of Phanodorm, of tablets according to the Formularium Nederlandse Apothekers (1968; FNA), and an aqueous solution. Six healthy volunteers participated in the investigation on three occasions and each received the three preparations. The dose administered was 300 mg cyclobarbital calcium. Plasma concentrations of cyclobarbital were determined at regular intervals. Absorption from the three preparations was rapid and was faster from the solution. Peak concentrations were usually attained within 1 h. The elimination of cyclobarbital could be described by a single first-order process with an average half-life of 11.6 h (range 8 – 17 h). There was little intra-subject variation of the half-life. Relative bioavailability for each volunteer was estimated by comparing the areas under the plasma concentration curves. The FNA-tablets and Phanodorm exhibited similar bioavailability, whereas the average bioavailability of the solution was 78% of that of FNA-tablets; the reason for this unexpected finding is unknown. It was concluded that cyclobarbital cannot be regarded as a uniformly suitable drug for the treatment of insomnia. The long half-life that was apparent in some of the volunteers (15 – 17 h) creates a substantial risk of residual effects on the following morning. In principle, however, the calcium salt of cyclobarbital may be used for induction of sleep, because of its rapid absorption.
    Materialart: Digitale Medien
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  • 108
    ISSN: 1432-1041
    Schlagwort(e): Halofantrine ; Malaria falciparum ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Halofantrine is a new blood schizontocidal drug used for the treatment of multidrug-resistant falciparum malaria. The pharmacokinetics of halofantrine (HAL) and its principal metabolite, N-desbutylhalofantrine (BHAL), was investigated in 6 adult male patients of Melanesian origin with uncomplicated falciparum malaria. The patients received 500 mg of halofantrine hydrochloride at times 0, 6 and 12 h (total 1.5 g). All patients responded to treatment with a mean parasite clearance time of 52.7 h and a mean fever clearance time of 33.8 h. The following kinetic parameters (mean values) were determined for HAL and BHAL, respectively: maximum plasma concentration (Cmax)=896 and 491 ng·ml−1; time to reach the Cmax (tmax)=15 and 56 h; elimination half-life (t1/2)=91 and 79 h and the mean residence time (MRT)=71 and 102 h. Based on the clinical response the plasma concentrations of HAL and BHAL were adequate for the treatment of uncomplicated falciparum malaria in the 6 patients.
    Materialart: Digitale Medien
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  • 109
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 165-169 
    ISSN: 1432-1041
    Schlagwort(e): Fosinopril ; fosinoprilat ; CAPD ; ACE-inhibitor ; pharmacokinetics ; pharmacodynamics ; peritoneal dialysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics and pharmacodynamics of fosinoprilat, the diacid of fosinopril sodium, a new angiotensin-converting enzyme (ACE) inhibitor, were investigated after the oral administration of 10 mg of fosinopril sodium to 6 chronic ambulatory peritoneal dialysis (CAPD) patients. The results from 1 patient are reported separately because of the presence of concomitant liver dysfunction. The mean t1/2, Cmax, tmax, and AUC values for 5 of the CAPD patients were 19.5 h, 202 ng·ml−1, 4.8 h, and 3.19 μg·h·ml−1, respectively. Values for 1 CAPD patient with liver dysfunction were t1/2 of 65.4 h, Cmax of 182 ng·ml−1, tmax of 9 h, and AUC of 18.1 μg·h·ml−1. Peritoneal clearance of fosinoprilat was negligible, ranging from 0.07 to 0.23 ml·min−1. Serum ACE activity remained significantly suppressed at 24 and 48 h after fosinopril sodium administration with mean decreases from baseline of 94.2% and 70.6%, respectively. ACE activity was suppressed to an even greater degree in the patient with liver dysfunction, remaining 97% inhibited 72 h after drug administration. Plasma renin activity (PRA) increased and plasma aldosterone concentrations decreased following drug administration. Mean arterial pressure did not change appreciably throughout the study. Dosage reductions may not be necessary in the majority of dialysis patients.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 171-174 
    ISSN: 1432-1041
    Schlagwort(e): Bisoprolol ; pharmacokinetics ; obesity ; blood flow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of a single i. v. dose of dlbisoprolol 0.16 mg·kg−1 ideal body weight has been studied in 8 obese women (mean weight 91 kg; 161% of ideal body weight) and 8 non-obese women (51 kg; 94% of ideal body weight). Compared to the controls, the obese subjects showed an increase in the total apparent volume of distribution (Vz) (182 vs 135 1) and a decrease in Vz per kg body weight (2 vs 2.7 l·kg−1). There was a negative correlation between Vz l·kg−1 and the percentage of ideal body weight (r=−0.672). Total body clearance was increased, but t1/2 and renal clearance was unchanged. It is concluded that tissue diffusion of bisoprolol in obese subjects is limited, despite its lipophilicity, possibly because of alteration in the blood flow to adipose tissue produced by bisoprolol.
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 175-178 
    ISSN: 1432-1041
    Schlagwort(e): Bopindolol ; pharmacokinetics ; beta-adrenoceptor blocker ; age ; hydrolysed bopindolol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Steady-state pharmacokinetic parameters of the new, long-acting beta-adrenoceptor blocker bopindolol have been measured in 17 young and 20 elderly healthy men. The t1/2β and the AUC(0→24 h) of hydrolysed bopindolol (the active metabolite) were both increased (40% and 26%, respectively) in the elderly subjects but tmax, Cmax and CL/f were not altered. However, after adjusting the parameters to allow for the different average body weights of the two groups, Cmax and CL/f became significantly different (+29% and −30%, respectively). AUC(0→24 h) was increased by 41%. The changes of up to 41% in pharmacokinetic parameters were smaller than the alterations of 50–100% usually seen when titrating doses of antihypertensive drugs. The clinical relevance of the effects was not examined, but similar changes have been reported for other beta-blockers which did not appear to be clinically relevant and did not affect the dosage required to treat hypertension.
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  • 112
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 179-183 
    ISSN: 1432-1041
    Schlagwort(e): Cefadroxil ; saturable absorption ; saturable renal tubular reabsorption ; cephalexin ; competitive inhibition ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetic behaviour of cefadroxil was dose-dependent in healthy male volunteers following the oral administration of single doses of 5, 15, and 30 mg · kg−1. As the dose of cefadroxil increased from 5 to 15 and 30 mg · kg−1, the peak plasma concentrations, normalized to 5 mg · kg−1, decreased significantly from 15.1 to 10.7 and 7.6 mg·l−1, while the corresponding normalized areas under the plasma concentration-time curves from 0 to 2 h decreased significantly from 1258 to 946 and 801 min·mg·l−1. When the same subjects were given 5 mg·kg−1 of cefadroxil together with 45 mg·kg−1 of cephalexin, the absorption of cefadroxil was slowed to a similar or greater extent than with the high dose of cefadroxil. Although the absorption rate decreased as the dose increased, the systemic availability of cefadroxil was essentially complete at all doses, as judged by the 24 h urinary recoveries of the antibiotic. Kinetic analysis of the plasma concentration-time curves gave the best fit with a zero-order followed by a first-order absorption process, consistent with saturable intestinal absorption of cefadroxil. The elimination rate of cefadroxil was directly related to dose and plasma concentrations, and the clearance at the dose of 5 mg·kg−1 was significantly increased by the simultaneous administration of high-dose cephalexin. The renal clearance of cefadroxil ranged from 98 ml·min·l−1 at total plasma cephalosporin (cefadroxil + cephalexin) concentrations less than 2.5 mg·l−1 to 156 mg·l−1 at concentrations greater than 40 mg·l−1. These findings are consistent with saturable active gastrointestinal absorption and renal tubular reabsorption of cefadroxil, with competitive inhibition of both processes by cephalexin.
    Materialart: Digitale Medien
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  • 113
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 245-250 
    ISSN: 1432-1041
    Schlagwort(e): Org 10172 ; Digoxin ; heparinoid ; pharmacokinetics ; pharmacodynamics ; drug interactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Potential pharmacokinetic and pharmacodynamic interactions between a new low molecular weight heparinoid Org 10172 (bolus injection of 3250 anti-Xa units) and digoxin (0.25 mg once daily for 8 days) were studied in 6 healthy male volunteers using an open, randomised three-way cross-over design. Digoxin produced a slight increase in clearance of anti-Xa activity from 4.3 to 4.8 ml·min−1, while plasma anti-thrombin and thrombin generation inhibiting (TGI) activity remained unchanged. Digoxin did not affect the actions of Org 10172 on the clotting tests. In the presence of Org 10172 there was a reduction in the AUC of digoxin during one dosing interval after the seventh digoxin tablet from 20 to 17 ng·ml−1·h, and a significant reduction in the average serum digoxin conentration. Since renal digoxin clearance was not significantly changed this probably might be due to a change in the non-renal clearance of digoxin. Atrio-ventricular node conduction, as measured by PR-time intervals, remained unchanged during all three treatments. In conclusion, although the pharmacokinetics of Org 10172 and digoxin were slightly changed by the combination, it is probably safe to administer Org 10172 and digoxin simultaneously. The clinical relevance of the slight decrease in plasma anti-Xa activity levels cannot yet be defined.
    Materialart: Digitale Medien
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  • 114
    ISSN: 1432-1041
    Schlagwort(e): Tiaprofenic acid ; children ; pharmacokinetics ; NSAID
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary. Twelve healthy children in three age groups anaesthetized for minor surgery were given a single oral dose of tiaprofenic acid (3 mg · kg−1) (TA). Seven blood samples and zero to 8 and 8 to 24 h urines were collected. TA concentrations in plasma and urine were measured by HPLC. No significant difference was found between the age groups in the kinetic parameters of TA and no correlation was found between these parameters and age; tmax=2.12h, Cmax=8.78mg · l−1, AUC(0→8 h) 33.9mg · h · l−1, AUC=39.3 mg · h · l−1, t1/2=2.35 h, Vz=0.319 l · kg−1, CL=0.094 l · h−1 · kg−1. Renal clearance was 14 ml · h−1. kg−1. 33% of the TA dose was recovered in the 24 h urine, 48% of which was conjugated, whereas in adults, TA is only found in urine as conjugates. The apparent plasma clearance was significantly higher (56%) than in 12 healthy adults given 1.5 mg · kg−1 TA. Volume of distribution and t1/2 did not significantly differ between children and adults. Since no relationship has been established between plasma TA and either efficacy or toxicity, a different dose regimen cannot be recommended in 3–11 year-old children from that in adults.
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  • 115
    ISSN: 1432-1041
    Schlagwort(e): Alprazolam ; benzodiazepines ; pharmacokinetics ; pharmacodynamics ; sublingual dosage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We gave 12 healthy male volunteers 1 mg of alprazolam or placebo on three occasions after a standard breakfast in a double-blind, randomized, single-dose, three-way crossover study. The three trials were: (a) oral alprazolam and sublingual placebo; (b) oral placebo and sublingual alprazolam; (c) placebo by both routes. Plasma alprazolam concentrations during 24 h after each dose were measured by electron-capture gas-liquid chromatography. Peak plasma concentrations were reached later after sublingual than oral dosage (2.8 vs 1.8 h, P〈0.01). Other kinetic variables were not significantly different: peak plasma concentration, 11.3 vs 12.0 ng·ml−1; elimination half-life, 12.5 vs 11.7 h; and total area under the plasma concentration versus time curve, 197 vs 186 h·ng·ml−1. Pharmacodynamic measures showed that sublingual and oral alprazolam both produced sedation, fatigue, impaired digit symbol substitution, slowing of reaction time, and impairment of the acquisition and recall of information. These changes were initially observed at 0.5 h after dosage and lasted up to 8 h. In general the two routes were significantly different from placebo but not from each other.
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  • 116
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 42 (1992), S. 445-448 
    ISSN: 1432-1041
    Schlagwort(e): Ethanol ; whole blood ; plasma ; total body water ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of ethanol in plasma and whole blood have been investigated and the results used to estimate the volume of total body water (TBW) by means of the dilution principle. Fifteen men (mean age 62 y) were given 0.6 g ethanol/kg body weight as an intravenous infusion over 1 h. The peak concentration of ethanol in plasma was 120 mg·dl−1 compared to 108 mg·dl−1 for whole blood. The disappearance rate of ethanol from plasma was 18.6 mg·dl−1·h−1 compared to 17.0 mg·dl−1·h−1 for the whole blood concentration-time data. The apparent volume of distribution of ethanol (Vz) was 0.54 l·kg−1 according to plasma kinetics compared to 0.59 l·kg−1 for the kinetics derived from whole blood. The mean area under the curve (AUC) was 294 mg·dl−1×h for plasma kinetics compared to 266 mg·dl−1×h for whole blood. The TBW was 40.9 l or 50.9% of body weight for the plasma concentration-time data. This agreed well with the 40.3 l or 50.1% of body weight obtained using whole blood.
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  • 117
    ISSN: 1432-1041
    Schlagwort(e): Methylprednisolone ; Rheumatoid arthritis ; bioavailability ; pharmacokinetics ; clinical response ; pulse steroid therapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A commercially available 1.0 g intravenous (i.v.) dosage formulation of methylprednisolone, as the sodium hemisuccinate salt (Solu MedrolR, Upjohn) was administered both parenterally and orally (pulse steroid therapy) on separate occasions, to eight elderly (mean 65 y) patients with active rheumatoid arthritis. The relative oral bioavailability of the sterol was 69.2%. Elimination of methylprednisolone was prolonged when given orally; the mean residence times were 7.23 h and 3.94 h for oral and i.v. administrations, respectively. Clinical response to pulse steroid therapy was no different with respect to route of administration. There were no significant differences in standard clinical and laboratory assessments of disease activity when the two therapies were compared. Oral administration of methylprednisolone in patients requiring high-dose pulse steroid therapy is convenient and avoids the discomfort and inconvenience associated with i.v. administration.
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  • 118
    ISSN: 1432-1041
    Schlagwort(e): Acetyl-L-carnitine ; Senile Dementia of Alzheimer Type ; pharmacokinetics ; plasma concentration ; cerebrospinal fluid concentration ; carnitine metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Acetyl-L-carnitine (ALC), a physiological component of the L-carnitine family, has been proposed for treating Alzheimer's disease in pharmacological doses. As this condition requires prolonged therapy, its kinetics has been examined after a multiple dose regimen, involving different routes of administration, in 11 patients suffering from Senile Dementia of Alzheimer Type. The study design comprised a 3-day basal observation period, sham treatment with repeated blood sampling; treatment with 30 mg·kg−1 i.v. given twice for 10 days (plasma kinetics was studied on the 7th day), and 50 days of 2.0 g/day p.o. given in three daily doses. Total acid soluble L-carnitine, L-carnitine and acetyl-L-carnitine in plasma and CSF were evaluated using an enantioselective radioenzyme assay. Short chain L-carnitine esters were calculated as the difference between total and free-L-carnitine. The plasma concentrations of individual components of the L-carnitine family did not change during the three days of the basal period, nor were they affected during the sham therapy period. Following the i.v. bolus injections, the plasma concentrations showed a biphasic curve, with average t1/2 of 0.073 h and 1.73 h, respectively. At the end of oral treatment, plasma acetyl-L-carnitine and L-carnitine short chain esters were significantly higher than during the run-in phase. The CSF concentrations paralleled those in plasma, suggesting that ALC easily crosses the blood-brain barrier. It is concluded that i.v. and oral administration of multiple doses of ALC can increase its plasma and CSF concentration in patients suffering from Alzheimer's disease.
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  • 119
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 42 (1992), S. 95-99 
    ISSN: 1432-1041
    Schlagwort(e): Ofloxacin ; Haemodialysis ; ofloxacin metabolites ; pharmacokinetics ; multiple doses ; dosage selection ; renal failure ; adverse effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary 7 patients with end-stage renal disease on regular haemodialysis were treated orally with a loading dose of 200 mg ofloxacin and multiple maintenance doses of 100 mg per 24 h for 10 days. The pharmacokinetics of ofloxacin and its metabolites were studied at the end of the treatment period. Plasma and dialysate concentrations of ofloxacin and ofloxacin metabolites were measured by HPLC. Peak (3.1 mg·1−1) and trough levels (1.6 mg·1−1) and the AUC of ofloxacin were comparable to the values in healthy volunteers given 300 to 400 mg ofloxacin p.o. The mean half-life, determined in the dialysis-free interval (t1/2β) and during the haemodialysis session (t1/2HD), was 38.5 h and 9.9 h, respectively. Extrarenal clearance (32.7 ml·min−1) was unchanged as compared to that reported in healthy volunteers after a single dose of ofloxacin. The fractional removal by haemodialysis amounted to 21.5%. Two metabolites, ofloxacin-N-oxide and demethyl-ofloxacin, were detected in plasma. Despite prolonged t1/2β of both metabolites (66.1 and 50.9 h) and multiple doses of ofloxacin the peak concentrations of the metabolites reached only 14% and 5% of that of the parent drug, respectively. It is concluded that in patients on regular haemodialysis treatment the dosage adjustment employed resulted in safe and therapeutically favourable plasma concentrations. The observed accumulation of ofloxacin metabolites does not appear to have any toxic or therapeutic significance.
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  • 120
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 34 (1988), S. 77-82 
    ISSN: 1432-1041
    Schlagwort(e): N-acetylcysteine ; pharmacokinetics ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics and bioavailability of N-acetylcysteine (NAC) have been determined after its intravenous and oral administration to 6 healthy volunteers. According to a randomized cross-over design each subject received NAC 200 mg i.v. and 400 mg p.o., and blood samples were collected for 30 h. Reduced NAC had a volume of distribution (VSS) of 0.59 l·kg−1 and a plasma clearance of 0.84 l·h−1·kg−1. The terminal half-life after intravenous administration was 1.95 h. The oral bioavailability was 4.0%. Based on total NAC concentration, its volume of distribution (VSS) was 0.47 l·kg−1 and its plasma clearance was 0.11 l·h−1·kg−1. The terminal half-life was 5.58 h after intravenous administration and 6.25 h after oral administration. Oral bioavailability of total NAC was 9.1%.
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  • 121
    ISSN: 1432-1041
    Schlagwort(e): BW443C ; enkephalin ; opioid peptide ; healthy volunteers ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied 16 healthy men to evaluate preliminary pharmacodynamics and kinetics of BW443C given by i.v. infusions. Four volunteers received escalating doses at weekly intervals, starting at 0.1 µg·kg−1 for 60 min and increasing to a maximum of 2.0 µg·kg−1·min−1 for 180 min. Subsequently 12 different subjects received single i.v. infusions of 10 µg·kg−1·min−1 for 20 min. Subjective effects were reported and objective measurements made of central nervous and cardiovascular effects. Blood was sampled at intervals on all occasions, plasma concentrations were determined by radioimmunoassay and pharmacokinetic profiles were analysed using NONLIN. Dry mouth and some nasal stuffiness were reported and postural hypotension occurred in 5/16 subjects at plasma concentrations 〉0.8 µg·ml−1. Supine blood pressure was well maintained in all subjects and hypotension resolved within 60–90 min of discontinuing the infusion. There was no evidence of sedation, mood change, nausea, vomiting, miosis, change in accomodation or respiratory depression. Rapid infusions produced transient feelings of warmth, heavy eyelids, heavy legs, and increased bowel sounds, which resolved despite increasing plasma concentrations. The disposition of the peptide was adequately described by a 2-compartment model with a mean ± SD plasma clearance of 123±18 ml·min−1 and a half-life of 2.0±0.4 h.
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  • 122
    ISSN: 1432-1041
    Schlagwort(e): Methotrexate ; non-steroidal anti-inflammatory drugs (NSAIDs) ; interaction ; disposition ; adverse effects ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied the pharmacokinetics of methotrexate in patients with rheumatoid arthritis concurrently treated with choline magnesium trisalicylate, ibuprofen, naproxen, or a non-NSAID analgesic (control treatment). The apparent systemic clearance of methotrexate was significantly reduced by all three treatments. Trisalicylate and ibuprofen both significantly reduced methotrexate renal clearance, but only the trisalicylate significantly displaced methotrexate from protein, increasing the fraction unbound by 28%. These data show that NSAIDs can affect the disposition of methotrexate, possibly increasing the potential for toxicity and necessitating dosage adjustments. However, large inter-subject variability precludes specific dosage recommendations.
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  • 123
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 34 (1988), S. 311-313 
    ISSN: 1432-1041
    Schlagwort(e): oxcarbazepine ; newborns ; antiepileptic ; placental transfer ; 10-hydroxy-carbazepine ; pharmacokinetics ; breast milk transfer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Gaschromatography — mass spectrometry (GC/MS) was used to determine plasma levels of oxcarbazepine (OCB) and its main metabolite in a newborn girl and her OCB-treated mother during the first five post partum days. At delivery the maternal and neonatal plasma concentrations were in the same range, indicating considerable placental transfer of both substances. In spite of ingestion of both substances via breast milk, there was no accumulation in the baby. On the fifth post partum day OCB and 10-hydroxy-carbazepine (10-OH-CB) levels in plasma in the newborn were only 12 and 7%, respectively, of the values found on the first day after delivery.
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  • 124
    ISSN: 1432-1041
    Schlagwort(e): doxifluridine ; colorectal carcinoma ; 5′-deoxy-5-fluorouridine ; 5-fluorouracil ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The disposition kinetics of a new 5-fluorouracil prodrug, 5′-deoxy-5-fluorouridine (5′dFUR, doxifluridine), were investigated in six patients with colorectal carcinoma. Each patient randomly received two single intravenous doses of 5′dFUR (2 and 4 g · m−2) on separate days. Plasma concentrations of 5′dFUR fell rapidly with terminal half-lives ranging from 16.1 to 27.7 min. A disproportionate increase in the area under the curve with increasing dose was seen in most patients. Doubling the dose resulted in a 40% decrease in nonrenal clearance (0.60 to 0.37 l · min−1) but no apparent change in renal clearance (0.32 to 0.29 l · min−1) or steady-state apparent volume of distribution (19.8 to 20.4 l). The mechanism for dose-dependence of 5′dFUR appears to be primarily due to nonlinear elimination associated with nonrenal processes rather than nonlinear plasma protein or tissue binding.
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  • 125
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 34 (1988), S. 475-479 
    ISSN: 1432-1041
    Schlagwort(e): liposomes ; sodium fluorescin ; pharmacokinetics ; clinical studies ; drug delivery ; normals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The in vivo kinetics and organ uptake of multilamellar liposomes have been studied in healthy volunteers. Sodium fluorescein-containing liposomes composed of equimolar amounts of egg phosphatidylocholine and cholesterol were injected into a peripheral vein in 4 healthy subjects. Blood samples collected from the femoral artery, hepatic vein and pulmonary artery, were analysed for liposomal dye content. The results, showing involvement of the reticuloendothelial system (RES) in the removal of liposomes, confirmed those previously obtained with radiolabelled preparations. Use of an innocuous liposomal marker (sodium fluorescein) and conventional vascular catheterization techniques, as employed here, may provide a reliable and clinically acceptable approach to establishing disease-induced changes in the kinetics of uptake of drug-containing liposomes by the RES, and thus help in the design of protocols for effective treatment.
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  • 126
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 34 (1988), S. 469-473 
    ISSN: 1432-1041
    Schlagwort(e): xamoterol ; cardiac failure ; beta1-adrenoceptor partial agonist ; pharmacokinetics ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of xamoterol, a β-adrenoceptor partial agonist under clinical evaluation for the treatment of mild to moderate heart failure, have been studied in 12 healthy male subjects. They received 14 mg i.v. and oral doses of 50 and 200 mg as a tablet and 200 mg as a solution in a 4 way cross-over design. After i.v. dosing the elimination half-life was 7.7 h, the total body clearance was 224 ml·min−1 and the volume of distribution at steady-state (Vss) was 48 l. Sixty-two percent of the dose was recovered unchanged in urine. After oral doses, the absolute bioavailability of xamoterol was shown to be 5% irrespective of whether the dose was administered as a tablet or solution. Peak plasma concentrations occurred at about 2 h for the tablet dose and slightly earlier (1.4 h) for the solution. Peak plasma concentration, AUC and urinary recovery of unchanged drug increased in proportion to dose. The apparent elimination half-life after oral doses (16 h) was significantly longer than that observed after an intravenous dose. Despite the low bioavailability, the degree of inter-subject variability of oral bioavailability was small probably indicating that the controlling factor is the hydrophilic nature of the molecule rather than extensive first pass metabolism or poor dissolution of xamoterol from the tablet formulation.
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  • 127
    ISSN: 1432-1041
    Schlagwort(e): Midazolam ; pharmacokinetics ; intranasal ; intravenous ; children ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Twelve children 1–5 y old were randomly assigned to receive midazolam 0.2 mg·kg−1 either by the intravenous (IV) or intranasal (IN) routes. After IN administration the rapid onset of absorption was observed (tmax 12 min). After both routes of administration the half-life was similar (2.2 h IN and 2.4 h IV). After IN administration the apparent plasma clearance and volume of distribution were about twice as high as after IV administration. The results are consistent with an estimated mean bioavailability of 55%.
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  • 128
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 359-361 
    ISSN: 1432-1041
    Schlagwort(e): Diabetes ; Antipyrine ; undernutrition ; drug metabolism ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In developing countries diabetics frequently suffer from varying grades of malnutrition. The combined effect of malnutrition and non-insulin dependent diabetes (NIDDM) on the drug metabolising enzyme system has been evaluated using antipyrine as a protodrug. All the patients were under treatment and their plasma glucose values were within normal limits. The AUC of antipyrine was similar in all the groups. Although none of the kinetic parameters was altered in normal diabetics, the clearance of antipyrine was decreased and its half life was prolonged, with an increase in volume of distribution, in undernourished diabetics compared to undernourished controls. The results indicate that diabetes per se may not influence antipyrine kinetics when the blood glucose is well under control, but in the presence of undernutrition, it significantly alters the disposition of the drug.
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  • 129
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 43 (1992), S. 567-569 
    ISSN: 1432-1041
    Schlagwort(e): Mefloquine ; Tetracycline ; Thai subjects ; Thai subjects ; drug interaction ; pharmacokinetics ; adverse effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The kinetics of a single oral dose of mefloquine given either alone or with tetracycline has been studied in 20 healthy Thai male volunteers. There was a significantly higher maximum whole blood mefloquine concentration after coadministration with tetracycline (1600 vs 1160 ng · ml−1), as well as a significantly reduced terminal half-life (14.4 vs 19.3 days), mean residence time (11.9 vs 16.0 days) and volume of distribution at steady state (13.3 vs 19.91 · kg−1). Although there was no significant change in the AUC from zero time to infinity, the AUC from zero time to 7 days was significantly increased by tetracycline (6.18 vs 4.76 μg · ml−1 · day). The changes in mefloquine disposition after tetracycline treatment are probably due to a reduction in enterohepatic recycling. The initial increase in mefloquine AUC without an apparent increase in side-effects suggests that this combination may have a place in the treatment of multi-drug resistant falciparum malaria.
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  • 130
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 379-382 
    ISSN: 1432-1041
    Schlagwort(e): Codeine ; paracetamol ; codeine-6-glucuronide ; pharmacokinetics ; metabolism ; partial clearance ; drug interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Plasma and urine concentrations of codeine and its measurable metabolites were determined by HPLC in six healthy subjects after a single 30 mg oral dose of codeine either alone or after 7 doses of 1 g paracetamol 8 hourly. After codeine alone, the t1/2 (h), AUC (μmol·l−1·h) and CLR (ml·min−1) for codeine were 2.2, 0.81, and 252 respectively. These were not significantly altered by paracetamol: 2.2, 0.84, and 291 respectively. For codeine-6-glucuronide the values were 2.4, 22.0, and 29.7 respectively. These were not significantly different from those after codeine plus paracetamol: 2.4, 21.9, and 39.6. There were no significant differences between the two treatments in the apparent partial clearances (ml·min−1) of codeine to morphine (88 codeine alone, 70 codeine plus paracetamol), to norcodeine (71 codeine alone, 88 codeine plus paracetamol), and to codeine-6-glucoronide (820 codeine alone, 1022 codeine plus paracetamol). The urinary excretion of codeine-6-glucuronide, morphine, norcodeine, and codeine were not significantly different between the two treatments.
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  • 131
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 4 (1971), S. 54-58 
    ISSN: 1432-1041
    Schlagwort(e): pharmacokinetics ; infusion ; plasma expander ; blood level fluctuation ; sulfonamide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Beschreibung / Inhaltsverzeichnis: Summary A hypothetical pharmacokinetic model is reported which describes the decreasing fluctuations in the blood levels of a sulfonamide during infusion of a plasma expander. Its concentration in the serum increases reciprocally with the amount of plasma expander infused. These procedures can be described by simple equations, and it is possible therefore, to calculate the dose required to maintain a constant blood level during the infusion.
    Notizen: Zusammenfassung Es wird über ein hypothetisch-pharmakokinetisches Modell berichtet, welches sich mit der absinkenden Serumkonzentration eines Sulfonamids nach Infusion eines Plasmaexpanders beschäftigt. Die Serumkonzentration fällt reziprok zur infundierten Menge des Plasmaexpanders ab. Die Vorgänge lassen sich durch einfache Gleichungssysteme beschreiben. Es gelingt daher, eine Zusatzdosis zu berechnen, welche den bei Infusionsbeginn bestehenden Plasmaspiegel annähernd konstant erhält.
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  • 132
    ISSN: 1432-1041
    Schlagwort(e): Cyclosporine ; Hyperlipidaemia ; heart transplantation ; fenofibrate ; fenofibric acid ; pharmacokinetics ; drug interaction ; nephrotoxicity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Cyclosporine (Cy) binds to lipoproteins in plasma. In order to test if its pharmacokinetics would be modified when efficient lipid-lowering treatment is introduced, a study has been done of Cy pharmacokinetics and any interaction with the lipid-lowering agent fenofibrate in hyperlipidaemic long-term, survivors of heart transplantation. Fenofibrate 200 mg once daily significantly reduced blood lipids (cholesterol 6.5 vs 7.7 mmol/l; apoprotein B 1.2 vs 1.6 g/l) but did not modify mean whole blood Cy trough levels (113 before fenofibrate vs 103 ng·ml−1), Cmax (812 ng·ml−1 by RIA and 757 ng·ml−1 by HPLC before fenofibrate versus 865 and 741 respectively, during fenofibrate); tmax (1.6 and 1.7 h before fenofibrate versus 1.4 and 1.4 h respectively), and t1/2 (13.9 and 11.1 h versus 9.5 and 10.7 h). The only adverse effect was an increase in creatinine (157 vs 145 mmol/l). Further studies are needed to investigate the mechanism of Cy-fenofibrate nephrotoxicity and to evaluate the long-term efficiency and safety of fenofibrate after heart transplantation.
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  • 133
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 45 (1993), S. 255-260 
    ISSN: 1432-1041
    Schlagwort(e): Ramipril ; Propranolol ; interaction ; pharmacokinetics ; pharmacodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied the pharmacodynamic effects of ramipril, propranolol, and their combination, as well as the effect of propranolol on the pharmacokinetics of ramipril in 12 healthy men (age 24 (SD 6) y, weight 72 (7) kg). Propranolol and placebo, ramipril and placebo, or propranolol and ramipril were given orally for four days in a crossover, double-blind fashion. The pharmacokinetics of ramipril and ramiprilat were investigated on day 4. Effects on plasma renin activity, ACE activity, and heart rate and blood pressure both before and after a standardized exercise test were measured on days 1 and 4. On day 4 the combination reduced the mean arterial pressure by 2.8 mmHg compared with propranolol alone and by 3.7 mmHg compared with ramipril alone. Ramipril had no effect on the bradycardia induced by propranolol. Propranolol reduced exercise mean arterial pressure by 9 mmHg (day 4) and heart rate by 7 beats.min−1 (day 4) compared with ramipril; this was not affected by co-administration of ramipril. On day 4 the average plasma renin activity was not significantly higher than after the combination. ACE activity was not affected by propranolol. The pharmacokinetics of ramipril and ramiprilat were not influenced by propranolol. The combination of ramipril and propranolol has additive pharmacodynamic effects that may be useful in the treatment of hypertension.
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  • 134
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 45 (1993), S. 275-277 
    ISSN: 1432-1041
    Schlagwort(e): Fenoterol ; Pregnancy ; pharmacokinetics ; premature labour
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of the β2-adrenergic drug fenoterol, which is used as a tocolytic agent in pregnancy, has been investigated in pregnant (n=9) and nonpregnant (n=5) women during a constant rate intravenous infusion. Clearance and mean residence time were found to be 1990 (1879/2220; Median, Q25/Q75) ml/min and 9.2 (8.0/14.0) min in the pregnant and 2126 (1915/2130) ml/min and 16.6 (16.5/32.1) min in the nonpregnant women, respectively. In addition, fenoterol clearance was estimated in 88 women from a single blood sample collected at steady state during IV therapy and the effect of gestational age on clearance was studied. Clearance displayed large inter-individual variation. There was no apparent correlation between clearance and gestational age. We conclude that there is no need to adjust the dose on pharmacokinetic grounds in the course of pregnancy.
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  • 135
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 195-197 
    ISSN: 1432-1041
    Schlagwort(e): Cefotaxime ; Renal insufficiency ; desacetylcefotaxime ; pharmacokinetics ; children
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary It is generally assumed that the renal clearance of drugs in patients with renal impairment are affected to a similar extent regardless of the type of renal disease (intact nephron hypothesis). We have studied the effect of underlying renal disease on the pharmacokinetics of cefotaxime and desacetylcefotaxime in two groups of children (ages 7 to 16 y) with varying degrees of renal dysfunction. Patients in group 1 (n=5) had intrinsic renal disease and those in group 2 (n=5) had extrinsic renal disease, as identified by the primary renal lesion. After a single intravenous dose of cefotaxime timed blood and urine samples were collected for 24 h; cefotaxime and desacetylcefotaxime were measured by HPLC. There were no significant differences between the groups in age, body surface area, urine output, creatinine clearance, total body clearance, nonrenal clearance, renal clearance, and volume of distribution at steady state of cefotaxime, and renal clearance of desacetylcefotaxime. However, the renal clearance: creatinine clearance (CLR:CLCR) ratios for both cefotaxime [1.34 in group 1 vs. 0.51 in group 2] and desacetylcefotaxime [1.58 in group 1 vs. 0.75 in group 2] were statistically significant between the two groups. Group 1 patients had an average CLR:CLCR ratio greater than 1 for both the parent compound and the metabolite, suggesting that net tubular secretion was still intact, despite a diminished glomerular filtration rate (CLCR=24 ml·min−1·1.73 m−2). In contrast, patients in group 2 (CLCR=49) ml·min−1·1.73 m−2) had an average CLR:CLCR ratio less than 1 for both cefotaxime and desacetylcefotaxime, suggesting that renal tubular transport mechanisms did not remain functional in these patients. Our findings suggest that the effect of renal insufficiency on the renal elimination of cefotaxime and its metabolite desacetylcefotaxime may depend on the cause of renal insufficiency.
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  • 136
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 253-258 
    ISSN: 1432-1041
    Schlagwort(e): Bioelectrical impedance ; Gentamicin ; non-invasive technique ; neonates ; predictive models ; pharmacokinetics ; plasma levels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The use of bioelectrical impedance (BI) analysis as a non-invasive approach for individualising gentamicin therapy in newborn infants has been investigated in a two phase study. In Phase I, 1/impedance and length2 were identified as statistically significant predictors of the distribution volume of gentamicin (Adj R2=0.78, CV=12.42%), and length2/impedance and post-conceptual age were predictors of total systemic clearance (Adj R2=0.83, CV=14.5%), following the administration of 2.5 mg·kg−1 gentamicin to 17 neonates (gestational age (GA) 27 to 36 weeks). In a prospective validation of these relationships in an independent (Phase II) group of 27 infants (GA 26 to 41 weeks), predicted serum gentamicin concentrations were close to those achieved. Several instances of high prediction errors (predicted minus achieved levels) were observed in infants with known or suspected renal impairment and they caused significant (P〈0.05) perturbation in the bias and accuracy of the models. Daily BI measures over a four to five day period were able to detect individual changes in the fat-free body compartments, which were translated into alterations in gentamicin regimens. This simple, non-invasive and relatively inexpensive bedside technique provides a potentially valuable means to individualise gentamicin therapy without relying on the measurement of serum gentamicin concentration.
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  • 137
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 357-360 
    ISSN: 1432-1041
    Schlagwort(e): Famotidine ; Reflux oesophagitis ; intraoesophageal long-term pH-metry ; pharmacodynamics ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics, pharmacodynamic effect and clinical efficacy of famotidine were studied in 10 patients with reflux oesophagitis Grades I and II. For the pharmacokinetic studies the patients received 20 mg famotidine i. v. The half-life of famotidine was 3.8 h, the total plasma clearance was 297 ml·min−1, and a steady state volume of distribution of 1.21·kg−1 was found. For pharmacodynamic assessment, intraoesophageal pH-metry was performed without and after acute treatment with famotidine 20 mg i. v. and following 3 weeks of oral famotidine 80 mg b. d. The resultant percentage total acid exposure time (pH〈4 within 24 h) were 23.9%, 19.0% and 19.2% (median), respectively (NS). At the end of 6 weeks of oral therapy, symptomatic and endoscopic improvement had occurred in 9 and 5 patients, respectively. Our study shows that the pharmacokinetics of famotidine in patients with reflux oesophagitis is comparable to that in healthy volunteers and peptic ulcer patients. The clinical response to the treatment appeared comparable to that found after other H2-receptor antagonists.
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  • 138
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 365-367 
    ISSN: 1432-1041
    Schlagwort(e): Ciprofloxacin ; Diazepam ; quinolone ; benzodiazepine ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effects of pretreatment with a seven day course of ciprofloxacin on pharmacokinetics and pharmacodynamics of an intravenous (5 mg) dose of diazepam were investigated in a group of 12 healthy volunteers in a double-blind placebo-controlled crossover study. Ciprofloxacin pretreatment significantly reduced diazepam CL (without ciprofloxacin: 19.5 ml·h−1kg−1; with ciprofloxacin: 12.3 ml·h−1kg−1). Diazepam t1/2 was also prolonged (without ciprofloxacin: 36.7 h; with ciprofloxacin: 71.1 h), but volume of distribution was unaltered (without ciprofloxacin: 1.1 l·kg−1; with ciprofloxacin: 1.1 l·kg−1). However, no significant changes were detected in psychometric tests of digit symbol substitution, tapping rate and short memory, as well as levels of concentration, vigilance and tension measured by visual analogue scales.
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  • 139
    ISSN: 1432-1041
    Schlagwort(e): Temocapril ; Liver dysfunction ; angiotensin converting enzyme inhibitor ; diacid ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Six subjects with normal liver function (Group 1) and 7 patients with liver dysfunction (Group 2; mean ICGR15 value 30.5 (5.2) %; range 16 to 56) received a single oral dose of 1 mg temocapril, a prodrug-type ACE inhibitor, with preferentially excreted by the biliary route. The plasma temocapril concentrations in Group 2 at 30 min and 1 h postdose were significantly higher than in Group 1, but the difference had disappeared 2 h postdosing. Although the half life of temocapril diacid in Group 2 was significantly longer than in Group 1, there was no significant difference between the two groups in AUC, Cmax or tmax. In Group 2, urinary recovery of temocapril was significantly increased, suggesting a possible delay in the bioactivation of temocapril into the diacid, but recovery of the diacid itself was not abnormal. ACE inhibitory action in Group 2 remained unchanged. Temocapril is regarded as an ACE inhibitor the disposition and efficacy of which are little affected in patients with impaired liver function.
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  • 140
    ISSN: 1432-1041
    Schlagwort(e): Isradipine ; Diclofenac ; pharmacokinetics ; platelet aggregation ; drug interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In this open, two-period crossover study in 18 healthy male volunteers, a single oral dose of 50 mg diclofenac was administered alone and on day 7 of multiple oral dosing of 5 mg b.i.d. isradipine to assess a possible pharmacokinetic interaction. The effect of these drugs on ex vivo platelet function was also determined. Serial blood samples were obtained over 12-hour periods on three occasions: after the single diclofenac dose; after the morning dose of isradipine on day 6 and after co-administration of both drugs on day 7 of steady-state isradipine administration. Additional samples were taken at 2 h post dose for determination of ex vivo platelet aggregation. Isradipine plasma concentrations were determined by a gas chromatographic method and diclofenac plasma concentrations by an HPLC method. The pharmacokinetic characteristics of diclofenac were unaltered during co-administration. The maximum plasma concentration of isradipine was increased 19.6% during co-administration from 5.06 to 6.05 ng·ml−1. This is not expected to be of clinical importance. Isradipine's apparent total body clearance and steady-state AUC remained unchanged. Ex vivo induced platelet aggregation was not affected by any of the treatments.
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  • 141
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 579-583 
    ISSN: 1432-1041
    Schlagwort(e): Cefixime ; renal failure ; pharmacokinetics ; volunteers ; adverse effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of cefixime following a single oral dose of 200 mg have been investigated in 6 normal subjects and in 22 patients with various degrees of renal insufficiency. Serum and urine samples were collected between 0 and 72 h and were subjected to two methods of analysis: bioassay and HPLC. There was a linear relationship between the two sets of results from 228 samples. This result suggests that none of the metabolites, which may accumulte in uraemic patients, has antibacterial activity. In normal subjects, the peak serum level (Cmax) was 2.50 μg·ml−1 at 2.83 h (tmax); the apparent elimination half-life (t1/2) was 3.73 h; the apparent total body clearance (CL·f−1) was 154 ml·min−1, the mean renal clearance (CLR) was 39.1 ml·min−1 and the apparent fraction of the dose recovered in 24 h urine was 0.22. In uraemic patients, Cmax and tmax were slightly increased and t1/2 was increased to 12–14 h in patients with an endogenous creatinine clearance below 20 ml·min−1. The apparent volume of distribution was decreased. Apparent total and renal clearances were lower in proportion to the degree of renal insufficiency. Linear relationships were found between CL/f, CLR and creatinine clearance (CLCR). The findings suggest that the dose of cefixime needs to be reduced only in patients with severe renal failure.
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  • 142
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 41 (1991), S. 603-607 
    ISSN: 1432-1041
    Schlagwort(e): Chlormezanone ; pharmacokinetics ; elderly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of Chlormezanone (CM) has been determined after a single oral dose of 400 mg CM in 5 young volunteers (28 y) and in 8 elderly patients (79 y). In the young subjects, CM was rapidly absorbed and distributed, and was slowly eliminated with a half-life of 38 h major metabolites were not detected in plasma or urine. Only 3% of CM was excreted unchanged in urine. In elderly patients absorption was delayed but not reduced; the Cmax and AUC did not differ from those in younger subjects, the elimination rate was reduced compared to the younger subjects (mean 54 h). The increase was in part related to the reduction in renal function and metabolism observed in aging. However, the change in pharmacokinetics was moderate and no adjustment in dosage seems necessary for treatments of limited duration in elderly patients.
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  • 143
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 45 (1993), S. 555-558 
    ISSN: 1432-1041
    Schlagwort(e): Glucagon ; pharmacokinetics ; i.v. infusion ; intranasal spray ; intramuscular administration ; insulin-dependent diabetes mellitus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics of intranasal, an intravenous infusion, and intramuscular glucagon has been studied in 5 healthy subjects and 11 patients with insulin-dependent diabetes mellitus. After infusion the elimination half-life was significantly longer in diabetics (11.9 vs 6.6 min) and the apparent volume of distribution was twice as high in diabetics (0.19 vs 0.37 l·kg−1). The metabolic clearance rates were the same in the two groups (18.9 and 21.3 ml·min−1·kg−1 in controls and in diabetics) and were about twice those previously reported. After 1 mg intranasally the Cmax of immunoractive glucagon (IRG) was similar in diabetic and in healthy subjects. Administration of a higher dose (2 mg) to diabetic patients produced a higher plasma level, although not proportionately so. The AUC after 1 mg was also similar in controls and in diabetics. The elimination half-life in both groups was similar to the value found after IV infusion; it was significantly shorter in controls (5.5 min) than in diabetics (13.8 min). In both groups, mean Cmax was significantly lower than after IM glucagon, the relative bioavailability of 1 mg intranasally vs IM injection being less than 30%. After IM administration, the Cmax and AUC of IRG in controls and in diabetic patients, were identical. The apparent elimination half-life was also similar in the two groups, and was three- to four-times longer (28.6 and 31.4 min) than after infusion or intranasal administration, possibly because estimation of the t1/2 was affected by slow release of the hormone from the site of injection.
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  • 144
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 45 (1993), S. 563-569 
    ISSN: 1432-1041
    Schlagwort(e): Chlorpromazine ; metabolites ; N-oxide ; sulfoxide ; 7-hydroxy ; conjugates ; pharmacokinetics ; first pass metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A study was carried out in 11 healthy young men to investigate the pharmacokinetics of chlorpromazine (CPZ) after a bolus intravenous (IV) dose (10 mg) and three single oral doses (25, 50 and 100 mg), with a washout period of two weeks between doses. Plasma levels of CPZ, CPZ N-oxide (CPZNO), CPZ sulfoxide (CPZSO) and both free and conjugated 7-hydroxy-CPZ (7-HOCPZ) were measured by extraction radioimmunoassays. CPZ exhibited multicompartmental pharmacokinetics in most subjects. There was wide between-subject variability in half life (11.05 h), volume of distribution (1215 l), volume of distribution at steady state (642 l) and mean residence time (8.88 h), whereas systemic clearance was somewhat less variable (76.6 l·h−1). All metabolites were present in measurable concentrations in the plasma of 9 of 11 subjects after IV CPZ, whereas free 7-HOCPZ was not detected in the other 2 individuals. With the exception of CPZNO, the biological half lives of the primary metabolites were longer than the half life of CPZ. After oral administration, the percentage of CPZ reaching the systemic circulation intact (F%) was very low (4–38%) and dose dependant. Moreover, both within-subject and between-subject variances were very high. The maximum plasma concentration (Cmax) and area under the plasma concentration versus time curve extrapolated to infinite time (AUC) showed evidence of nonlinearity, whereas half life did not appear to be dose dependant. These data suggest that the high degree of variability in the pharmacokinetics of CPZ is a result of extensive first pass metabolism rather than variation in half life. The mean AUC for the total conjugates of 7-HOCPZ was about two fold higher than that of the parent drug or any other metabolite. This shows that phase II metabolism plays a very significant role in the disposition of CPZ. As a result, the role of CYP2D6 in the 7-hydroxylation of CPZ cannot be fully assessed without taking phase II metabolism into account.
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  • 145
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 45 (1993), S. 585-587 
    ISSN: 1432-1041
    Schlagwort(e): Flumazenil ; benzodiazepine ; absorption ; disposition ; elderly volunteers ; pharmacokinetics ; aging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In an open design, randomised, two-way cross-over study, a single 2 mg i.v. dose and a single 30 mg oral dose of flumazenil were each administered to a group of healthy young (n=6) and elderly (n=12) volunteers (male: female 2/1). Plasma samples were collected at intervals and intact drug was assayed. Both the IV and oral doses of flumazenil were very well tolerated by both age groups and no severe or unexpected adverse effects were observed. The main complaints were dizziness and headache, mainly after oral dosing, probably due to the higher Cmax and AUC following this route of administration. After 2 mg i. v. the disposition parameters in the two age groups (elderly/young) were very similar: volume of distribution (Vss): 0.88/0.901·kg−1; total body clearance (ClPL): 0.86/0.99 l·min−1; terminal elimination half-life (t1/2β): 1.02/0.91 h. After the 30 mg oral dose the mean Cmax of 87.6 ng·ml−1 (elderly) and 78.4 ng·ml−1 (young) were generally reached within 0.5 to 1 h. In 26% (elderly) and 23% (young), the absolute bioavailability of flumazenil was very similar. It is concluded that the absorption and disposition paramters of flumazenil were not significantly affected by aging.
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  • 146
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 27-33 
    ISSN: 1432-1041
    Schlagwort(e): Nicorandil ; vasodilator ; tolerance study ; blood pressure ; pharmacokinetics ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied the effects of intravenous nicorandil, a mixed arterial and venous vasodilator, in 48 healthy volunteers. Nicorandil (20, 28, 39, 54, 74, 103, 144, or 200 μg·kg−1) or placebo were given over 5 min to subjects supine (16 subjects, 2 doses) or sitting (32 subjects, 1 dose) in a single-blind crossover design. Electro-cardiographic intervals, blood pressure, and heart rate were measured before and for 8 h after dosing. Blood and urine safety laboratory studies were also performed before and after dosing. All intravenous infusions of nicorandil and placebo were well tolerated and there were no clinically important safety concerns. The most frequent adverse event after nicorandil was headache (24 events by 19 subjects), although its occurrence was not strictly dose related. One subject experienced transient symptomatic hypotension (144 μg·kg−1). Mean plasma nicorandil concentrations were dose-related and fell with a half-life of 0.7 to 1.2 h. Systemic clearance and volume of distribution tended to decrease as dose increased. Sitting subjects showed marginally lower (〈20%) systemic clearances and larger values of Cmax and AUC. Nicorandil produced dose-related reductions in blood pressure, with consistent statistically significant differences from placebo after the 144 and 200 μg·kg−1 doses. The falls in blood pressure were greater for diastolic pressure and in this supine position. At 200 μg·kg−1, the mean falls in systolic/diastolic pressures (mm Hg) during the first hour were 10.9/14.7 supine and 6.1/9.1 sitting; systolic pressure returned to baseline after 8 h and diastolic pressure after 4 h. Heart rate increased transiently (mean peak increase of 17–24 bpm at the end of the 144 and 200 μg·kg−1 infusions). Blood pressure and heart rate changes over time were statistically significantly correlated with plasma nicorandil concentrations. Individual areas under the blood pressure and heart rate change curves likewise correlated with plasma concentration curve areas.
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  • 147
    ISSN: 1432-1041
    Schlagwort(e): Buspirone ; pharmacokinetics ; renal impairment ; hepatic impairment ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The single dose and steady-state pharmacokinetics of buspirone and its metabolite 1-pyrimidinyl piperazine (1-PP) have been evaluated in normal volunteers and patients with renal or hepatic impairment, using a parallel group design, with assignment of patients to study group on the basis of the degree of renal (mild, moderate, severe) or hepatic (compensated or decompensated) impairment. Each healthy volunteer or patient received a single dose of 10 mg buspirone on Day 1 of the study, and starting 36 h after the first dose, healthy volunteers and patients received 10 mg doses of buspirone every 12 hours for 9 days. On the morning of Day 10 they received the last dose. Serial blood samples were collected on Days 1, 5 and 10 and plasma was analysed for buspirone and 1-PP. The plasma concentrations of buspirone and 1-PP were highly variable regardless of the renal or hepatic function. The peak concentrations (Cmax) and area under the curves (AUC) of buspirone and 1-PP on Days D 5 and 10 were higher than on Day D 1. The trough levels (Cmin) and AUCs (D 5 and 10) of buspirone and 1-PP indicated, that, regardless of renal or hepatic function, steady state was reached after 3 to 5 days of dosing. At steady-state, patients with renal or hepatic impairment had significantly higher Cmax and AUC values of buspirone than in normal volunteers. However, the intensity and frequency of adverse experiences in patients with renal or hepatic impairment were not significantly different from those observed in normal volunteers. There was no correlation between the average plasma concentrations of buspirone ( $$\bar C$$ ) and the degree of renal impairment judged by creatinine clearance. An excellent correlation was observed between $$\bar C$$ of buspirone and serum albumin (r=0.862, and P〈0.0001) as well as between $$\bar C$$ and bromsulphalein clearance (r=0.678, P〈0.0003). In view of high intra-and inter-subject variability in buspirone concentrations, definitive dosing recommendations for patients with compromised renal or hepatic function could not be made, but such patients should initially be dosed cautiously with buspirone.
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  • 148
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 42 (1992), S. 219-222 
    ISSN: 1432-1041
    Schlagwort(e): Thiamine ; pharmacokinetics ; analytical method ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A novel liquid chromatographic method for the determination of thiamine in plasma has been developed and has been used to study plasma thiamine concentrations after multiple dosage regimens for 11 days. The method involves purification, concentration and analytical separation of thiochrome on-line, using a switching column system. Ten healthy men were given 500 mg thiamine i.m. once a day (Group 1) and ten were given 250 mg p.o. every 12 h (Group 2). The times to reach steady state (7 and 5.6 days for Groups 1 and 2, respectively) were not different (P〉0.05). The mean elimination half-life was 1.8 days. The mean minimum steady-state concentration after the oral regimen (23 μg·l−1) was 78% of that after the intramuscular regime (29 μg·l−1).
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  • 149
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. S31 
    ISSN: 1432-1041
    Schlagwort(e): Cefmenoxime ; Renal failure ; continuous haemofiltration ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The elimination of cefmenoxime after single and repeated i. v. dosing was studied in 12 patients with severe renal failure and sepsis during continuous haemofiltration. More than 30 % of the drug was found in the filtrate. The sieving coefficient (S) was 0.54. Vss % was unchanged 0.311 · kg−1 in comparison with patients with normal renal function, whereas the mean t/12ß was prolonged to about 16 h, and total clearance was reduced 20.8 ml · min−1 · 1.73 m−2. Once daily administration of 1 g cefmenoxime is suggested as the appropriate dose under such circumstances.
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  • 150
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 171-176 
    ISSN: 1432-1041
    Schlagwort(e): Oxprenolol ; β-adrenoceptor blockade ; circadian rhythm ; haemodynamics ; pharmacokinetics ; exercise ; healthy volunteers ; kinetic-dynamic model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied the effect of dosage time of oxprenolol (Trasicor®) on its pharmacokinetics and pharmacodynamics in six healthy volunteers. The drug effects measured were heart rate and systolic blood pressure during exercise. Oxprenolol was taken orally at 08.00 h, 14.00 h, 20.00 h, and 02.00 h in randomized order, with 1 week between successive doses. There were differences in the pharmacokinetics of oxprenolol for the ratio between the apparent volume of distribution and systemic availability (P=0.04) and for elimination half-life (P=0.006). Both were lowest after administration at 14.00 h (163 (77) l and 1.2 (0.6) h; mean (SD)) and highest after administration at 02.00 h (229 (100) l, and 1.7 (0.6) h). The systolic blood pressure during exercise before oxprenolol did not vary with dosage time, but heart rate during exercise before intake was lowest before dosage time 08.00 h and highest before dosage time 20.00 h (P=0.03). The time-course of heart rate during exercise after oxprenolol was described by a model that incorporated the factors drug concentration and spontaneous diurnal variation. EC50 and Emax did not vary between dosage times. The spontaneous diurnal variation in heart rate during exercise was unaffected by oxprenolol, leading to an apparently greater effect of oxprenolol during the night than during the day.
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  • 151
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. S53 
    ISSN: 1432-1041
    Schlagwort(e): Quinapril ; Renal failure ; quinaprilat ; haemodialysis ; ACE inhibitor ; pharmacokinetics ; pharmacodynamics ; peritoneal dialysis ; adverse effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The pharmacokinetics and pharmacodynamics of the ACE inhibitor quinaprilat have been studied in six chronic haemodialysis (HD) patients and in six patients undergoing continuous ambulatory peritoneal dialysis (CAPD) after a single oral dose of 2.5 mg quinapril. Mean tmax and Cmax values (SEM) for quinaprilat in interdialytic HD patients were 4.0 (0) h and 84 (8.4) ng · ml−1 respectively, and they did not differ significantly from those in CAPD patients (4.7 (0.7) h and 64 (5.7) ng · ml−1). Elimination half lives were 30 (10.1) h (HD) and 34 (7.3) h (CAPD). Cmax, tmax, t/12, and AUC were increased and CL was decreased compared to data reported previously after giving 2.5 mg to healthy subjects. Peritoneal clearance was calculated as 0.1 (0.1) ml · min−1, thus less than 0.5 % of the dose were removed within 24 h by CAPD. ACE activity was suppressed by more than 93 % between 4 and 24 h postdose (P 〈 0.001). It decreased in both groups with increasing plasma quinaprilat levels. Angiotensin II concentration compared to baseline was significantly decreased at 4 hours (−30.4±10 %) and 24 h (−30±9.9 %) (P 〈 0.05,n=11), while active plasma renin concentration was still significantly increased at 48 h postdose (+60.2±14.5 %,P 〈 0.01). Mean arterial pressure 24 h postdose was significantly (P 〈 0.05) decreased in HD (−12 mm Hg) and CAPD patients (− 20 mm Hg). Only two patients reported unwanted effects (fatigue, dizziness, nausea, and weakness). In conclusion, due to its long lasting effect on ACE activity and on blood pressure in terminal renal failure a starting dose of quinapril 2.5 mg o. d. may be used in hypertensive HD and CAPD patients.
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  • 152
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 371-373 
    ISSN: 1432-1041
    Schlagwort(e): Salmon calcitonin ; Skin blister fluid concentration ; synthetic ; plasma concentration ; pharmacokinetics ; adverse effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract To obtain further information about the availability of salmon calcitonin in the biophase compartment that surrounds the receptor site, salmon calcitonin concentrations in plasma and skin blister fluid (SBF) after a single IV dose of 100 IU synthetic salmon calcitonin were compared in 15 healthy volunteers. Serial blood and SBF samples were collected before and up to 8 h after administration and calcitonin was determined by a specific RIA. The maximum concentration in plasma was 225 pg·ml-1 (in the first sample at 15 min), whereas in SBF the mean peak of 84 pg·ml-1 was reached after about 30 min. The distribution of salmon calcitonin into SBF, defined as the ratio of the AUCs in SBF and plasma, was 1.5. The kinetic profiles of salmon calcitonin in plasma and interstitial fluid were different. Calcitonin in plasma peaked and then levelled out, while in SBF it persisted longer than in plasma. This is the first report of the distribution of salmon calcitonin into blister fluid.
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  • 153
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 361-364 
    ISSN: 1432-1041
    Schlagwort(e): Tulobuterol ; β2-adrenoceptor agonist ; aerosol inhalation ; transdermal delivery ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied the pharmacokinetics of tulobuterol given transdermally or by aerosol inhalation in healthy male volunteers. Tulobuterol was rapidly absorbed after inhalation, with a tmax of 0.8–1.5 h. The Cmax and the AUC increased linearly with dose. Tulobuterol was well absorbed after transdermal administration, with an absorption lag-time of about 4 h. The Cmax and AUC increased linearly with dose and the tmax was about 9–12 h. The mean percentage of drug absorbed during the application of a patch for 24 h was 82–90% after a single dose and 82–85% during repeated dosing. The mean urinary recoveries as unchanged drug after a single inhalation and patch application were 3–4% and 5–6% respectively. Tulobuterol did not accumulate during repeated inhalation or transdermal application. It was well tolerated, except for an increase in heart rate of 10–20 beats · min−1 after five repeated applications of a 4 mg patch.
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  • 154
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 387-389 
    ISSN: 1432-1041
    Schlagwort(e): Flosequinan ; Congestive heart failure ; elderly ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have investigated the pharmacokinetics of the direct vasodilator flosequinan in elderly patients with congestive heart failure. Eight patients received a single dose of 50 mg, and 8 patients received once-daily treatment with 25 mg for two weeks. In the single dose study, the tmax of flosequinan was 2.5 h, Cmax was 1.17 μg · ml−1 and t1/2 was 5.63 h. The tmax of the metabolite BTS 53554 was 20.3 h, Cmax was 1.44 μg · ml−1 and t1/2 was 62.0 h. BTS 53554 accumulated gradually in the 14-day repeated dose study and steady-state was reached after approximately 2 weeks. Flosequinan was not found to accumulate. Adverse reactions were not observed in either the single or repeated dose study. It is advisable to consider renal function and body weight when flosequinan is to be administered to elderly patients with congestive heart failure. The initial dose should be 25 mg.
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  • 155
    ISSN: 1432-1041
    Schlagwort(e): Metoprolol ; controlled-release formulation ; hydrochlorothiazide ; pharmacokinetics ; pharmacodynamics ; healthy volunteers ; efficacy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied a controlled-release formulation containing metoprolol 100 mg and hydrochlorothiazide 12.5 mg. We compared the pharmacokinetics of both substances and the pharmacodynamics of metoprolol with those of a conventional combination tablet. The controlled-release formulation gave less variable plasma metoprolol concentrations, Cmax 138 nmol·l−1 and Cmin 74 nmol·l−1, whereas for the conventional formulation the mean Cmax of metoprolol was 629 nmol·l−1 and the Cmin 20 nmol·l−1. Despite lower relative systemic availability (68%) for metoprolol from the controlled-release formulation and a smaller AUC, metoprolol from the controlled-release formulation produced a greater total effect, calculated as the area under the curve of the effect on exercise heart rate vs. time (303 vs. 259%·h; P〈0.05). Hydrochlorothiazide was rapidly absorbed from both formulations and the plasma concentration profiles were almost superimposable. Controlled-release metoprolol with hydrochlorothiazide combines effective β1-adrenoceptor blockade for 24 h without affecting the pharmacokinetics of hydrochlorothiazide.
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  • 156
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 157-159 
    ISSN: 1432-1041
    Schlagwort(e): Torasemide ; metabolites ; end-stage renal disease ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The pharmacokinetics of torasemide, a new loop diuretic, as well as its active metabolites M1 and M3, and its inactive main metabolite, M5, were studied in 12 patients with end-stage renal failure during single i.v. (n=6) or single oral (n=6) dosing of 200 mg torasemide, and during chronic oral treatment for 9 days (n=12). The elimination half-life (t1/2) of torasemide was unchanged in renal failure, whereas t1/2 of the torasemide metabolites M1, M3, and M5 were markedly prolonged. However t1/2 as well as the area under the plasma level time curve of torasemide and its metabolites were unchanged during chronic compared to acute administration. The results of this study suggest that despite the increased half-life of torasemide metabolites M1, M3 and M5 in end-stage renal failure patients, no accumulation of the parent drug torasemide and its metabolites during chronic dosing is demonstrable.
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  • 157
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1996), S. 387-391 
    ISSN: 1432-1041
    Schlagwort(e): Liver function tests ; elderly ; pharmacokinetics ; geriatrics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The pharmacokinetics of brofaromine, a selective inhibitor of monoamine oxidase A, was evaluated in 12 frail elderly patients (66–92 y) and 12 healthy volunteers (20–35 y). Methods: Quantitative liver function tests were performed to show whether brofaromine elimination in the elderly could be predicted from noninvasive assessment of CYP1A2 activity (caffeine clearance) or liver plasma flow (sorbitol clearance). Results: In the elderly the AUC of brofaromine was significantly increased (e.g. for the 75 mg dose 43.2 vs 19.9 μmol*h·l−1, clearance was reduced (5.0 vs. 11.8 l·h−1), the volume of distribution was smaller (130 vs. 230 l), and the half-life was slightly increased (19.0 vs. 14.2 h). No significant correlation was observed between hepatic plasma flow and brofaromine clearance (r=0.41, P=0.05), whereas CYP1A2 activity and brofaromine clearance were tightly correlated (r=0.94, P〈0.0001). Conclusion: Caffeine clearance, a simple, noninvasive test of CYP1A2 activity, is predictive of brofaromine clearance.
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  • 158
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1996), S. 411-415 
    ISSN: 1432-1041
    Schlagwort(e): Moxisylyte ; pharmacokinetics ; intracavernous administration ; healthy volunteers ; adverse events ; metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The concentration-time profiles of specific metabolites of moxisylyte, an α-adrenoceptor blocking agent, in the plasma and urine from 18 healthy volunteers were investigated after intracavernous (IC) administrations at three dose levels (10, 20 and 30 mg). Results: Four metabolites, unconjugated desacetyl-moxisylyte (DAM), DAM glucuronide, and DAM and monodesmethylated DAM (MDAM) sulphates were found in plasma and urine. For all metabolites, t1/2 elimination was independent of the administered dose (1.19 h for unconjugated DAM; 1.51 h for DAM glucuronide; 1.51 h for DAM sulphate; and 2.17 h for MDAM sulphate). Cmax and AUC increased in direct proportion to dose, except for the inactive DAM glucuronide. Any the differences detected were small and equivalence of the three doses can be accepted. Conclusion: The pharmacokinetics of moxisylyte in humans following intracavernous administration were linear in the dose range 10 to 30 mg.
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  • 159
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 77-81 
    ISSN: 1432-1041
    Schlagwort(e): Trapezoidal rule ; Ethinyl estradiol ; variance components ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The concept of a weighted pool for estimating the area under the curve (AUC) is presented and set in relationship to the trapezoidal rule. An example from a pharmacokinetic study on ethinyl estradiol is used to demonstrate the use of variance component analysis for relating the intraindividual variance of the AUC, trapezoidal rule and weighted pool to the variance of the determination process. Depending on the sampling times, the theoretical variance of the weighted pool is greater than the theoretical variance of the trapezoidal rule. In the example presented, it was shown that this difference is of no importance in relation to the interindividual variance of the AUC, which dominates the total variance. In the example study, routine quality control samples were also determined in each assay, which allowed independent confirmation of the discussed results on the intraindividual variance of the AUCs.
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  • 160
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 55-58 
    ISSN: 1432-1041
    Schlagwort(e): Pemirolast ; Asthma ; theophylline ; drug interaction ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The effect of a newly developed anti-allergic drug, pemirolast potassium (TBX), on the pharmacokinetics and metabolism of theophylline was investigated under steady-state conditions in seven healthy male volunteers. A sustained-release theophylline formulation (100 mg twice daily at 12 h intervals) was given as monotherapy and coadministered with TBX (10 mg twice daily at 12 h). Plasma concentration-time curves and the urinary excretion of theophylline and its major metabolites after administration of theophylline alone and after coadministration with TBX were compared. No significant adverse effects from this study were observed. There were no significant differences in the total body clearance, renal clearance and maximum concentration of theophylline between the two treatments, although coadministration of TBX significantly delayed the time to reach maximum concentration of theophylline. In the case of urinary excretion, no significant changes in the fraction of urinary excretion of theophylline and its metabolites were observed. These results indicate that TBX has little or no effect on the pharmacokinetics and metabolism of theophylline and suggest that TBX is safe for asthma patients receiving theophylline therapy for treatment of chronic obstructive airway diseases.
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  • 161
    ISSN: 1432-1041
    Schlagwort(e): Entacapone ; catechol-O-methyltransferase ; pharmacokinetics ; healthy volunteers ; adverse effects ; metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The inhibition of soluble catechol-O-methyltransferase (S-COMT) in red blood cells (RBCs) by entacapone, and the pharmacokinetics of entacapone after single oral (5–800 mg) and IV (25 mg) doses have been examined in an open study in 12 healthy young male volunteers. Oral entacapone dose-dependently decreased the activity of S-COMT in RBCs with a maximum inhibition of 82% after the highest dose (800 mg). The inhibition of S-COMT in RBCs was reversible and the activity recovered within 4–8 h. Entacapone showed linear pharmacokinetics over the dose range studied: Cmax and AUC were correlated with the dose of the drug. Oral absorption of entacapone was fast, with a tmax ranging from 0.4 to 0.9 h, depending on the dose. Systemic availability of entacapone varied between 30 and 46%. Entacapone was rapidly eliminated by metabolism with a half-life of 0.27–0.30 h after oral doses of 5 to 50 mg. After doses from 100 to 800 mg the disposition was best described by two phases with a t1/2α of 0.27–0.37 h and t1/2β of 1.59–3.44 h. Over the dose range studied, the single oral and IV doses of entacapone were well tolerated. No haematological, biochemical or haemodynamic adverse effects were seen. The results show that entacapone is an orally effective and reversible COMT inhibitor in man and has simple, linear pharmacokinetics.
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  • 162
    ISSN: 1432-1041
    Schlagwort(e): Diltiazem ; immediate-release tablet ; controlled-release tablet ; steady state ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract We have studied the controlled-release properties and relative systemic availabilities of two dosages of the same controlled-release (CR) diltiazem tablet formulation by comparing them at steady state with those of an immediate-release formulation. We measured 24-hour plasma concentration profiles during 4-day treatments with diltiazem 90 mg CR tablet bd diltiazem 120 mg CR tablet bd, and conventional diltiazem 60 mg immediate-release (IR) tablet tid. The study had a randomized, three-way crossover design. Twelve healthy men (38–52 y) participated. Trough plasma concentrations were determined on days 3 and 4. The 24-h plasma concentration-time profiles were assessed after the last morning dose on day 4 of each period. The following steady-state pharmacokinetic values were calculated: the minimum plasma concentration (Cmin), the maximum plasma concentration (Cmax), the time interval during which the plasma concentration exceeded 75% of Cmax (t75), the area under the plasma concentration-time curve (AUC72–96), the peak-to-trough fluctuation (PTF), and the area-under-the-curve fluctuation (AUCF). Steady state was achieved on day 3. The pharmacokinetics were comparable. For diltiazem CR 90 mg and diltiazem CR 120 mg, AUC84–96 (night) was approximately 75% of AUC72–84 (daytime). The diltiazem plasma concentration increased slowly from about 6 h after the evening dose of both CR tablets, resulting in relatively high plasma concentrations in the early morning hours. Only during treatment with diltiazem CR 120 mg were the plasma concentrations of diltiazem maintained above the minimum therapeutic plasma concentration of 50 μg·1−1 throughout the full 24 h. In conclusion, twice-daily treatment with diltiazem CR tablets can replace thrice-daily treatment with the conventional diltiazem IR tablet. The early morning rise of the diltiazem plasma concentration, which might lead to a lower incidence of ischaemic events, may be an important clinical advantage of both CR tablets. Because of the minimum therapeutic plasma concentration of 50 μg·1−1, twice-daily administration of the 120 mg CR tablet may be preferred from a therapeutic point of view. Diltiazem, a benzothiazepine, is a calcium antagonist used in the treatment of angina pectoris and hypertension. The anti-ischaemic mechanism of diltiazem seems to result from an increase of myocardial oxygen supply and a reduction in myocardial oxygen demand, respectively by coronary artery dilatation and/or direct and indirect haemodynamic effects, such as afterload reduction and heart rate decrease (Braunwald 1982). Its therapeutic effect is evident at daily dosages between 180 and 360 mg (Low et al. 1981). After oral administration it is almost completely absorbed from the gastrointestinal tract, but owing to extensive first-pass metabolism, its systemic availability is approximately 40–50% (Echizen and Eichelbaum 1986). The time to maximum plasma concentrations after oral administration of immediate-release formulations is approximately 3 to 4 h. The elimination half-life of diltiazem is 3.5–7 h, implying that frequent dosing is required to maintain effective plasma concentrations. Therefore, a controlled-release formulation of diltiazem, designed to be taken twice daily, has been developed. The aim of this crossover study was to compare the systemic availability and steady-state pharmacokinetics of a controlled-release diltiazem tablet formulation (90 and 120 mg) with those of a conventional diltiazem immediate-release tablet in healthy volunteers.
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  • 163
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 325-332 
    ISSN: 1432-1041
    Schlagwort(e): Factor IX ; Haemophilia B ; macromolecules ; pharmacokinetics ; methodological study
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The aims of this study were to investigate the influence of total blood sampling time on the estimated pharmacokinetic parameters of Factor IX procoagulant activity (FIX:C) and to relate the pharmacokinetics of FIX:C to the putative physiological disposition of Factor IX (FIX). Six patients with severe haemophilia B each received 2 infusions of FIX and on both occasions blood samples were collected for 104 h. Each FIX:C decay curve was processed with successive deletion of the last (remaining) datapoint. The fitted terminal half-life (t1/2β) and the calculated model-independent mean residence time (MRTMI), elimination clearance (CLMI) and volume of distribution at steady state (Vss) stabilised close to their final values when FIX:C data corresponding to at least 56 h of sampling were used. The final mean values were t1/2β=34 h, MRTMI=37 h, CLMI=4.0 ml · h-1 · kg-1 and Vss=0.15 l · kg-1. The disposition of FIX could be characterised by a two-compartment pharmacokinetic model. On average, FIX molecules spent 44% of their total MRT in the second (or “extravascular”) compartment. The distribution clearance was comparable to estimated total lymph flow. The volume of the central compartment was twice the estimated plasma volume, which may reflect the rapid and reversible binding of FIX to vascular endothelium. This explains the common clinical finding that the peak activity of FIX:C is less than the injected dose divided by the estimated plasma volume of the patient.
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  • 164
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 339-343 
    ISSN: 1432-1041
    Schlagwort(e): Iopromide ; X-ray contrast medium ; pharmacokinetics ; tolerability ; healthy volunteers ; adverse effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Twelve healthy male volunteers participated in a single-blind, randomised, placebo-controlled cross-over study of IV iopromide in doses of 15 g iodine or 80 g iodine infused over a period of 15 min. The volunteers were observed for three days during which time blood samples, urine and faeces were collected. The terminal disposition phase half-life of iopromide was 2 h and 1.9 h, and the total clearance was 110 and 103 ml·min-1 at the lower and at the higher dose levels, respectively. The steady state volume of distribution was 16 and 17 l, indicating predominantly extracellular distribution of iopromide. Statistical analysis (one-sided t-test) showed that all the target parameters (AUC, half-life and urinary excretion) were equivalent at both dose levels, indicating dose proportionate, first order kinetics of iopromide over the large dose range tested. Iopromide was well tolerated after both doses.
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  • 165
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 379-381 
    ISSN: 1432-1041
    Schlagwort(e): Ganciclovir ; Renal failure ; pharmacokinetics ; haemodialysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The pharmacokinetics of ganciclovir was evaluated in a 73-year old anuric, haemodialyzed patient given 1.25 mg·kg-1 at the end of each haemodialysis session, three times per week. A biexponential decrease in plasma ganciclovir was observed, with a peak concentration of 3.7 mg·1-1 followed by a steady state value of 2.6 mg·1-1 for almost 40 h. The total plasma clearance was 0.05 ml·min-1·kg-1, the volume of distribution at steady state was 0.61·kg-1, the elimination half life was 132 h, the area under curve was 372 μg·h·ml-1, the mean residence time was 190 h, and the percentage of ganciclovir cleared from plasma after a 5 h haemodialysis session was 52.1%. The simulated pharmacokinetics over one month, following the same scheme of administration, did not suggest marked accumulation of ganciclovir. These results were obtained after a reduction of 58% in the recommended dose in patients with impaired renal function.
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  • 166
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 389-391 
    ISSN: 1432-1041
    Schlagwort(e): Population approach ; Drug development ; software ; pharmacokinetics ; pharmacodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract An expert meeting to discuss population pharmacokinetic/pharmacodynamic software was held in Brussels in November 1993 under the auspices of the European Co-operation in Science and Technology (COST), Medicine (B1) programme. Recently developed statistical methods offer the possibility of gaining integrated information on pharmacokinetics and response from relatively sparse observational data obtained directly in patients who are being treated with the drug under development. These methods can minimize the need to exclude patient groups and also allow analysis of a variety of unbalanced designs that frequently arise in the evaluation of the relationships between dose or concentration on the one hand and efficacy or safety on the other relationships that do not readily lend themselves to other forms of statistical analysis. The purpose of the Brussels meeting was to evaluate the state of both existing software and software under development, and to specify the needs and wishes of potential users of such software. It was apparent from the meeting that software development for population data analysis is currently a very active area of investigation and that several very good packages are already available, with more in development. The general consensus of the meeting was that well validated, easy to use software was essential to the implementation of the population approach to drug development.
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  • 167
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 451-454 
    ISSN: 1432-1041
    Schlagwort(e): Pregnancy ; Paracetamol ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Paracetamol pharmacokinetics was evaluated in groups of pregnant (8–12 weeks) and non pregnant women given the standard oral dose of 650 mg. The mean half-life was significantly lower and oral clearance was significantly higher in the first trimester group compared to the control group. The AUC was lower in the first trimester but the difference was not significant. The maximum serum concentration (Cmax) was reached 48 min after administration in both groups, and the mean maximal serum concentration was similar in the pregnant and non-pregnant women (11.16 and 11.58 μg·ml−1). A correlation of r=0.85 was found between Cmax and the weight of the pregnant women (P〈0.01) but not with the weight of the control women, this suggests that weight gain might be used to determine the women in whom dosage adjustment is needed.
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  • 168
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 477-478 
    ISSN: 1432-1041
    Schlagwort(e): Theophylline ; flumequine ; drug interaction ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The kinetics of a single i. v. dose of theophylline given either alone or with flumequine was studied in eight healthy volunteers. No statistically significant differences were observed in the pharmacokinetic parameters of theophylline (volume of distribution, elimination half-life, AUC, plasma clearance) following the two treatments. Pretreatment for 5 days with oral flumequine (400 mg, three times daily) had no significant effect on the disposition of a single i. v. dose of theophylline in healthy volunteers.
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  • 169
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1995), S. 543-548 
    ISSN: 1432-1041
    Schlagwort(e): Sumatriptan ; pharmacokinetics ; single dose ; bioavailability ; dose proportionality ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Sumatriptan is classified as a vascular 5HT1 receptor agonist and is effective in the acute treatment of migraine and cluster headache. Sumatriptan is available as an injection for subcutaneous administration and as a tablet for oral administration. The pharmacokinetics of sumatriptan differ depending on the route of administration. The mean subcutaneous bioavilability is 96% compared to 14% for the oral tablet. The lower bioavailability following oral administration is due mainly to presystemic metabolism. The inter-subject variability in plasma sumatriptan concentrations is greater following oral administration and a faster rate of absorption of drug into the systemic circulation is achieved following subcutaneous dosing. The pharmacokinetics of sumatriptan are linear up to a subcutaneous dose of 16 mg. Following oral dosing up to 400 mg, the pharmacokinetics are also linear, with the exception of rate of absorption, as indicated by a dose dependent increase in time to peak concentration. Sumatriptan is a highly cleared compound that is eliminated from the body primarily by metabolism to the pharmacologically inactive indoleacetic acid analogue. Both sumatriptan and its metabolite are excreted in the urine. Although the renal clearance of sumatriptan is only 20% of the total clearance, it exceeds the glomerular filtration rate, indicating that sumatriptan undergoes active renal tubular secretion. Sumatriptan has a large apparent volume of distribution (170 1) and an elimination half-life of 2 h. Oral doses of sumatriptan were administered as a solution of dispersible tablets and subcutaneous dosing was by injection into the arm. In clinical practice, sumatriptan is administered as a film coated tablet or by subcutaneous injection into the thigh.
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  • 170
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 537-543 
    ISSN: 1432-1041
    Schlagwort(e): Lisinopril ; Dose adjustment ; ACE inhibitors ; pharmacokinetics ; pharmacodynamics ; renal failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract To prevent drug accumulation and adverse effects the dose of hydrophilic angiotensin-converting enzyme (ACE) inhibitors, e. g. lisinopril, must be reduced in patients with renal failure. To obtain a rational basis for dose recommendations, we undertook a prospective clinical trial. After 15 days of lisinopril treatment pharmacokinetic and pharmacodynamic parameters were determined in patients with advanced renal failure (n=8; endogenous creatinine clearance [CLCR]: 18 ml·min−1·1.73m−2) and in healthy subjects with normal renal function (n=16; CLCR: 107 ml·min−1·1.73m−2). The volunteers received 10 mg lisinopril once daily, the daily dose in patients (1.1–2.2 mg) was adjusted to the individual CLCR according to the method of Dettli [13]. After 15 days of lisinopril treatment the mean maximal serum concentration (C max) in patients was lower than in volunteers (30.7 vs 40.7 ng·ml−1, while the mean area under the concentration-time curve (AUC 0–24 h) was higher (525 vs 473 ng·h−1·ml−1). ACE activity on day 15 was almost completely inhibited in both groups. Plasma renin activity, angiotensin I and angiotensin II levels documented marked inhibition of converting enzyme in volunteers and patients. Furthermore, average mean arterial blood pressure in patients decreased by 5 mmHg and proteinuria from 3.9–2.7 g per 24 h after 15 days of treatment with the reduced dose of lisinopril. Adjustment of the dose of lisinopril prevents significant accumulation of the drug in patients with advanced renal failure during chronic therapy. Mean serum levels did not exceed this in subjects with normal renal function receiving a standard dose. Despite substantial dose reduction, blood pressure and proteinuria decreases were observed.
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  • 171
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 563-564 
    ISSN: 1432-1041
    Schlagwort(e): 2-Chloro-2′-deoxyadenosine (CdA) ; Protein binding ; Cladribine ; pharmacokinetics ; leukaemia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The plasma protein binding of 2-chloro-2′-deoxyadenosine (CdA) at 37°;C was studied by ultrafiltration in 5 healthy volunteers, in 11 patients with haematological malignancies and in purified protein preparations. In the patients, the binding of CdA to plasma proteins was 25.0% and in healthy subjects it was 21.1%. In a solution of human serum albumin (40 g·1−1), 24.3% CdA was bound, but less than 5% was bound in a solution of α1-acid-glycoprotein (0.7 g·1−1). No dependence of binding on the concentration of CdA was found within a range 25–1000 nmol·1−1. In conclusion, due to its limited binding to plasma proteins, any change in the binding of CdA is unlikely to have a major influence on its pharmacological effect.
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  • 172
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 49-52 
    ISSN: 1432-1041
    Schlagwort(e): Azithromycin ; Erythromycin ; Midazolam ; drug interaction ; healthy volunteers ; pharmacokinetics ; drug interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Since macrolide antibiotics inhibit the oxidative hepatic metabolism of various drugs, including midazolam, the present double blind studies were conducted to find out if azithromycin, a new macrolide of the azalide type, would inhibit the metabolism of midazolam and enhance the effects of midazolam on human performance. In Study I, 64 healthy medical students, divided in four parallel groups received placebo, midazolam (10 mg or 15 mg), and midazolam 10 mg combined with azithromycin (500mg+250mg). In Study II, three males received oral midazolam 10 mg in combination with placebo, azithromycin or erythromycin 750 mg (as a positive control) in a cross-over trial. Objective and subjective tests were done before the intake of midazolam and 30 and 90 min after it, and venous blood was sampled for the assay of midazolam. In the placebo group in Study I, the mean numbers of letters cancelled (LC) at baseline, 30 min and 90 min were 21, 20 and 20, respectively, and the corresponding mean numbers of correct digit symbol substitutions (DSS) were 126, 137 and 140, indicating a practice effect. Midazolam 10 mg impaired these performances (21, 13 and 12 for LC, and 127, 113 and 111 for DSS). Either dose of midazolam produced clumsiness, mental slowness and poor subjective performance, midazolam 15 mg being slightly more active. The corresponding, scores in the azithromycin + midazolam group were 21, 16, 16 for LC, and 132, 121 and 119 for DSS, the only significant difference from placebo being the impairment of DSS at 90 min. The combination differed from midazolam 15 mg in producing less drowsiness and mental slowness. In Study II, mean plasma midazolam concentrations (μg·1-1) after erythromycin + midazolam 10 mg were 0 (baseline), 168 (30 min) and 113 (90 min), which were higher than the values (0, 79 and 41) after placebo + midazolam. The corresponding concentrations (μg·1-1) after azithromycin + midazolam (0, 85 and 46) were similar to those found after placebo + midazolam. Erythromycin but not azithromycin enhanced the objective and subjective effects of midazolam. Our results suggest that as azithromycin, unlike erythromycin, does not interfere with midazolam metabolism, it also does not enhance the effects of midazolam.
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  • 173
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 53-55 
    ISSN: 1432-1041
    Schlagwort(e): Glibenclamide ; Diabetes ; NIDDM ; absorption ; hyperglycaemia ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract We have studied the absorption of glibenclamide 10 mg as a single morning dose in 7 patients with non-insulin-dependent diabetes mellitus, comparing normoglycaemic and hyperglycaemic states. The maximal glibenclamide plasma concentrations were significantly higher in the normoglycaemic than in the hyperglycaemic state (448 vs 228 mg·1-1) and these peak concentrations were attained faster in normoglycaemia than in hyperglycaemia (3.7 vs 5 h). We conclude that the absorption of glibenclamide in the two states is different.
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  • 174
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 57-60 
    ISSN: 1432-1041
    Schlagwort(e): Butorphanol ; transdermal ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract We have studied the effects of age and sex on the pharmacokinetics and the systemic availability of transnasal butorphanol in a randomized, two-way, crossover study of 48 subjects: young men and women, and elderly men and women. Each subject took a single 1 mg dose of intravenous and transnasal butorphanol tartrate on separate occasions with a one-week washout period. Blood samples were collected over 16 hours. Plasma butorphanol concentrations were determined using radioimmunoassay. The AUC of plasma butorphanol concentrations after an intravenous injection were higher in the elderly women than in the other groups. However, there were no significant differences in Cmax and AUC between the groups after transnasal administration. The mean systemic availability of transnasal butorphanol was about 70 %, except for the elderly women (48 %). After intravenous and transnasal administration, the half-life and mean residence time were greater in the elderly than the young. Clearance was lower in women than men. Apparent volume of distribution was higher for elderly men than the others. The age- and sex-related changes in the pharmacokinetics of transnasal butorphanol are not large enough to necessitate dosage differences.
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  • 175
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 67-69 
    ISSN: 1432-1041
    Schlagwort(e): Ofloxacin ; sucralfate ; food ; drug interaction ; absorption ; healthy volunteers ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract We have studied the effect of food on the interaction of ofloxacin with sucralfate. Six healthy men took a single oral dose of ofloxacin (200 mg) on 4 occasions: alone after overnight fasting or after breakfast (non-fasting), and with sucralfate fasting or non-fasting. There were no significant differences in the plasma concentration-time profiles of ofloxacin after ofloxacin alone between fasting and non-fasting conditions. On the other hand, the peak plasma concentration and AUC of ofloxacin after co-administration with sucralfate while fasting fell by 70 and 61 % compared with ofloxacin alone; the changes non-fasting were 39 and 31 % respectively. The interaction of ofloxacin with sucralfate was markedly reduced by food, but still could not be disregarded.
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  • 176
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 85-87 
    ISSN: 1432-1041
    Schlagwort(e): Mefloquine ; Enantiomers ; pharmacokinetics ; stereoselectivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract We studied the pharmacokinetics of the enantiomers of mefloquine in whole blood in healthy Thai volunteers after administration of a single oral dose of 750 mg of the racemic mixture. Mefloquine pharmacokinetics were stereoselective. The peak concentrations and areas under the curve of the (−) enantiomer were significantly higher than those of its antipode (0.79 versus 0.46 μg · ml-1 and 402 versus 94 μg · h · ml-1). The half-lives of (−)MQ were significantly longer than those of (+)MQ (531 versus 206 h). No stereoselectivity was observed for tmax values.
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  • 177
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 47 (1994), S. 187-193 
    ISSN: 1432-1041
    Schlagwort(e): NMR spectroscopy in vivo ; drug tissue concentration ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract NMR spectroscopy in vivo when applied to studying drugs and their metabolites usually measures relative concentration in a tissue over time. Only ratios of clearance and volume parameters can be estimated from these data. Low drug dosages (relative to the sensitivity of in vivo NMR) or rapid drug elimination create the additional problem of data sparsity where a pharmacokinetic model cannot be fitted individually. We have investigated whether relative and absolute pharmacokinetic parameters can be estimated from such data by applying a population model. The data analysed were relative concentractions of 5-fluorouracil (FU) and of the sum of its catabolits α-fluoro-β-ureido-propanoic acid (FUPA) and α-fluoro-β-alanine (FBAL) in te liver, as monitored in 16 cancer patients by [19F]-NMP spectroscopy during and after a 10-min intravenous infusion of 650 mg FU·m−2. The “structural” part of the population model was a non-linear, two-compartment model featuring one FU compartment with volume V FU , a saturable clearance of FU by conversion into the catabolites where CL=v max /(k M +C FU ), a catabolite compartment with volume V cat , and a concentration-independent clearance of the catabolites, CL cat . The parameters actually fitted were: γ, v max , k M ·V FU , V cat /V FU , and CL cat /V cat where γ is a proportionality factor relating the NMR signal intensity of FU to the amount of FU in the body and, therefore, has no purely pharmacokinetic interpretation. All parameters were checked for random interindividual variation; γ and v max were also tested for inter-occasion variation. The program system NONMEM was used for model fitting. The estimated mean population parameters were: v max =121 μmol·min−1, k M ·V FU =2590 μmol, V cat /V FU =0.0648, CL cat /V cat =0.0555·min−1. The proportionality factor γ was found to depend on body weight and, in addition, to have an inter-occasion random variation (within patients, between examinations). No other random variation of a kinetic parameter could be identified. The estimated v max is similar to a reported estimate of 2.02 μmol·min−1·kg−1 derived from FU plasma kinetics. This study shows that sparse relative concentration data can be analysed by using relative parameters in a population model. Only one parameter has no unequivocal pharmacokinetic meaning due to the lack of absolute concentration information. Any contribution of the measuring procedure to the inter-occasion variation of in vivo NMP spectroscopy measurements should be minimized in order to allow the detection of possible inter-individual variances of the pharmacokinetic parameters.
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  • 178
    ISSN: 1432-1041
    Schlagwort(e): Ranitidine bismuth citrate ; Tripotassium dicitrato bismuthate ; Duodenal ulcer ; bismuth ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract GR122311X (ranitidine bismuth citrate, Glaxo Group Research Ltd.) is a salt of ranitidine with a complex of bismuth and citric acid which is being developed for the treatment of peptic ulceration. In this study, 4 groups of 12 healthy male subjects were dosed for 10 days with either GR122311X 500 mg bid (301 mg bismuth per day), GR122311X 1.0 g bid (602 mg bismuth per day), tripotassium dicitrato bismuthate (TDB, DeNoltab, Gist Brocades Ltd., Weybridge, England) 240 mg bid (431 mg bismuth per day) or placebo. After the last dose the geometric mean for Cmax for 500 mg bid of GR122311X was 5 ng·g−1, for 1.0 g bid GR122311X it was 12 ng·g−1 and it was 21 ng·g−1 for 240 mg TDB bid. The corresponding trough plasma levels were 2 ng·g−1, 4 ng·g−1 and 4 ng·g−1, respectively. The AUC over a dosing interval after the last dose (AUCτ) were 34 ng·h·g−1, 71 ng·h·g−1 and 79 ng·h·g−1, respectively. The bismuth urinary recoveries over the last dosing interval (Aeτ) were 97 μg, 227 μg and 309 μg, respectively, which is less than 1 % of the administered doses. The renal clearance of bismuth was less than the glomerular filtration rate. After adjustment for bismuth dose, the Cmax for GR122311X 500 mg was 35 % that of TDB, while for GR122311X 1.0 g the Cmax was 42 % that of TDB. Similar differences were observed for Aeτ. In conclusion bismuth pharmacokinetics after oral administration of GR1223311X exhibited lower Aeτ and Cmax, with a much narrower Cmax range than those observed for TDB.
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  • 179
    ISSN: 1432-1041
    Schlagwort(e): Granisetron ; pharmacokinetics ; elderly ; tolerance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
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  • 180
    ISSN: 1432-1041
    Schlagwort(e): Growth hormone ; Jet-injection ; pharmacokinetics ; pharmacodynamics ; Somatomedin C ; free fatty acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The pharmacokinetics and pharmacodynamics of recombinant human growth hormone (rhGH) were studied after a single subcutaneous dose given by jet-injection, and have been compared with the results obtained after conventional needle-injection. Twelve healthy male volunteers completed an open label, randomised, two-way crossover study, with a 7-day washout period between the two single sc doses. Pharmacokinetic parameters were derived from rhGH concentrations in blood samples collected regularly over 24 h after dosing on Day 1 of each period. To investigate the pharmacodynamics, additional samples were taken for the analysis of somatomedin C (IGF-I) and free fatty acids (FFA). A higher and earlier Cmax was found after jet-injection (ratio (%) jet-injected/needle-injected 124; 90%-confidence interval 108 – 142). The AUC0−∞ for rhGH were similar (ratio (%) jet-injected/needle-injected 98; 90%-confidence interval 93 – 103). Both treatments were associated with a significant and similar rise in IGF-I. Both administrations of rhGH were associated with identical rhythmical changes in FFA. The study indicates that jet-injected and needle-injected rhGH are bioequivalent with respect to the amount absorbed. The criterion for bioequivalence is not met for the rate of absorption. It is unlikely that the latter finding will influence the pharmacodynamics of rhGH, since bioequipotency was established for the effect on IGF-I generation. Jet-injection was safe in use and was generally well tolerated.
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  • 181
    ISSN: 1432-1041
    Schlagwort(e): Losartan ; Cimetidine ; pharmacokinetics ; plasma renin activity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract This was a 2-period randomized, crossover study in 8 healthy males to determine the effects of cimetidine (400 mg q.i.d. for 6 days) on the pharmacokinetics and pharmacodynamic effects of the angiotensin II receptor antagonist, losartan (100 mg). Cimetidine increased the AUC for losartan 18% without affecting the AUC for E-3174, the active metabolite of losartan. The increase in plasma renin activity following losartan was not affected by cimetidine (maximum mean increases 12.6 and 12.1 ng Ang I·ml−1·h−1 without and with cimetidine, respectively). These results indicate that cimetidine does not appear to alter the pharmacokinetics or pharmacodynamics of losartan to a clinically significant extent.
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  • 182
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 48 (1995), S. 501-504 
    ISSN: 1432-1041
    Schlagwort(e): Quinidine ; CYP2D6 ; Sparteine oxidation polymorphism ; (3S)-3OH-quinidine ; quinidine-N-oxide ; dihydroquinidine ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Quinidine is a very potent inhibitor of CYP2D6, but the role of the enzyme in the biotransformation of quinidine has only been investigated in a single in vitro study and in two small in vivo experiments, with contradictory results. The present investigation was designed to present definite evaluation of whether quinidine is metabolised by CYP2D6. Eight poor metabolizers (PM) and 8 extensive metabolizers (EM) of sparteine each took one oral dose of 200 mg quinidine. In the EM, the total clearance, the clearance via 3-hydroxylation and the clearance via N-oxidation, were 33, 3.7 and 0.23 l·h−1, respectively. In the PM, the corresponding values were 29, 3.1 and 0.18 l·h−1, respectively. There were no statistically significant differences between EM and PM in any of these pharmacokinetic parameters. It is concluded that CYP2D6 is not an important enzyme for the oxidation of quinidine.
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  • 183
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1995), S. 221-228 
    ISSN: 1432-1041
    Schlagwort(e): Nefazodone ; Geriatric assessment ; Hepatic cirrhosis ; Renal impairment ; pharmacokinetics ; antidepressive agents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The single-dose pharmacokinetics of nefazodone (NEF) and its metabolites hydroxynefazodone (HO-NEF) and m-chlorophenylpiperazine (mCPP) were examined in 12 healthy younger subjects ≤55 years of age (YNG), 12 elderly subjects ≥65 years of age (ELD), 12 patients with biopsy proven hepatic cirrhosis (HEP) and 12 patients with moderate renal impairment (REN), ClCR 20–60 ml·min−1. The study was of parallel group design, with each of the four subject groups receiving escalating single oral doses of 50, 100 and 200 mg of nefazodone at 1 week intervals. Serial blood samples for pharmacokinetic analysis were collected for 48 h following each dose and plasma samples were assayed for NEF, HO-NEF and mCPP by a validated HPLC method. Single oral doses up to 200 mg of nefazodone were well tolerated by all subjects. Maximum plasma levels of NEF and HO-NEF were generally attained within 1 h after administration of nefazodone. HO-NEF and mCPP plasma levels were about 1/3 and 〈1/10 those of NEF, respectively. There were no apparent gender-related pharmacokinetic differences in any group of subjects. NEF and HO-NEF pharmacokinetics were dose dependent in all four subject groups; a superproportional increase in AUC and an increase in t1/2 with increasing dose was obtained, indicative of nonlinear pharmacokinetics. Relative to normal subjects, elderly and cirrhotic subjects exhibited increased systemic exposure to NEF and HO-NEF, as reflected by AUC, at all doses of nefazodone; subjects with moderate renal impairment did not. Elderly and cirrhotic patients may require lower doses of NEF to achieve and maintain therapeutic effectiveness.
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  • 184
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1995), S. 229-235 
    ISSN: 1432-1041
    Schlagwort(e): Nefazodone ; Renal impairment ; pharmacokinetics ; antidepressive agents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The steady-state pharmacokinetics of nefazodone (NEF) and its metabolites hydroxynefazodone (HO-NEF) and m-chlorophenylpiperazine (mCPP) were compared in subjects with normal and impaired renal function. Patients: The Study was of parallel group design which included 7 subjects with normal (NOR) renal function, CLCR≥72 ml·min−1·1.73 m−2, 6 with moderate (MOD) renal impairment, CLCR 31–60 ml·min−1·1.73 m−2 and 9 with severe (SEV) renal impairment, CLCR≤30 ml·min−1·1.73 m−2. Subjects in each renal function group received a 100-mg oral dose of nefazodone hydrochloride BID for 7 days and a single morning dose on day 8. Starting 48 h after the last 100-mg dose, 200-mg doses were administered on a similar schedule to 3, 4 and 3 subjects from each renal function group (NOR, MOD and SEV, respectively). Single trough blood samples just prior to each morning dose (Cmin) and serial samples after the dose on day 8 were obtained at each dose level for pharmacokinetic analysis. Plasma samples were assayed by a specific HPLC method for NEF, HO-NEF and mCPP. The CMIN data indicated that steady state was attained by the third day of BID administration of both the 100- and 200-mg doses of nefazodone, regardless of degree of renal function. Both NEF and HO-NEF attained steady-state Cmax within 2 h after administration of nefazodone; tmax for mCPP was less defined and more delayed. HO-NEF and mCPP plasma levels were about 1/3 and 〈1/10 those of NEF, respectively, regardless of the status of renal function. Steady-state systemic exposure of NEF and HO-NEF, as reflected by AUC and Cmax, and elimination t1/2 values did not differ significantly among renal function groups. Conclusion: The study results suggest that dose adjustments may not be necessary, but nefazodone should be used with caution in the presence of severe renal impairment.
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  • 185
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1996), S. 293-298 
    ISSN: 1432-1041
    Schlagwort(e): Key words Budesonide; enema ; pharmacokinetics ; healthy subjects ; hepatic bypass
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The pharmacokinetics and systemic availability of budesonide after rectal administration of two single enema doses (2 mg in 100 ml fluid of almost identical composition) were compared in 15 healthy volunteers. In 11 of these subjects, 2 mg oral budesonide in a gelatine capsule was given on a separate occasion. An intravenous administration (0.5 mg) was given as reference. With this design, individual hepatic bypass of the rectally administered budesonide dose could be estimated. The pharmacokinetics of the two enema formulations were similar, although not bioequivalent. Mean systemic availability was 16% (range 4.2–43%) and 15% (3.2–50%) after rectal administration and 6.3% (2.4–10%) after oral administration. The rectal data revealed a small intra- but a substantial inter-subject variability in systemic availability. Cmax was 3.3 nmol ⋅ l−1 (0.95–8.2), 3.0 nmol ⋅ l−1 (0.64–8.9) and 1.3 nmol ⋅ l−1 (0.61–3.0), respectively, for the three formulations. Absorption was rapid and essentially terminated within 3 h after rectal dosing [tmax = 1.3 h for both formulations (range 0.5–2.0)], but was slower after oral dosing [tmax = 2.1 h (1.0–6.0)]. If a complete absorption after oral and rectal dosing is assumed, the fraction of the rectal dose entering the liver at first pass can be calculated to be 88% (55–99%). The higher systemic availability and intersubject variability after rectal dosing does not seem to be caused by differences in first-pass liver metabolism but rather by hepatic bypass of a varying portion of administered drug. This portion seems to be typical for an individual and might be explained by anatomical differences between subjects.
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  • 186
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1995), S. 203-210 
    ISSN: 1432-1041
    Schlagwort(e): Felodipine ; pharmacokinetics ; haemodynamics ; congestive heart failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract In congestive heart failure patients the kinetics of felodipine, a dihydropyridine calcium antagonist, show interpatient differences after acute i.v. administration that disappear after 8 weeks oral treatment with a change in kinetics in the patients with the largest clearances (CL) and the smallest volumes of distribution (V SS). Pharmacokinetic and haemodynamic data were combined to construct a haemodynamic-pharmacokinetic model. This model shows that the differences between the patients in i.v. pharmacokinetics are consistent with a difference in plasma flow distribution between liver and poorly perfused tissues. In patients in whom kinetics changed, felodipine treatment is supposed to cause a redistribution of flow from liver to peripheral tissues, accompanied by a decreased work load of the heart and a larger increase in VO2max during therapy than in the other patients, whose workload increased. This suggests a better therapeutic response in the patients whose kinetics changed. As change in kinetics is related to felodipine CL and CL to liver plasma flow, felodipine CL or even indocyanine CL might be predictive for the therapeutic effect of felodipine.
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  • 187
    ISSN: 1432-1041
    Schlagwort(e): Cholesterol acyltransferase ; Hypocholesterolaemic ; 447C88 ; volunteers ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract 447C88 (N-Heptyl-N′-(2,4 difluoro-4-6-(2(-4-(2,2 dimethylpropyl)phenyl)ethyl)phenyl)urea) is an inhibitor of human microsomal AcylCoA:Cholesterol acyltransferase (ACAT) with an IC50 of 10.2 ng·ml−1 (23 nM). It is poorly absorbed but 5 mg·kg−1·day−1 completely abolishes the rise in plasma cholesterol in cholesterol-fed rats. In this study, twelve healthy, male volunteers received single, oral doses of 25, 50, 100, 200, 400 and 800 mg of 447C88 (n+8) or placebo (n+4) with food in a double-blind study with at least a week between occasions. The 400 mg dose was repeated after an overnight fast. Subsequently, fourteen different volunteers received a single 200 mg dose of 447C88 (n+8) or placebo (n+6) with food and, a week later, the same dose twice daily for 10 days; all doses were given with food. All doses were well tolerated with no significant changes in vital signs, full blood counts or plasma biochemical profiles. Plasma concentrations of 447C88 were unquantifiable after the fasting dose and low after all other doses. Mean Cmax and AUC were 1.8 ng·ml−1 and 9.0 ng·ml−1·h after 200 mg rising to 5.4 ng·ml−1 and 23.8 ng·ml−1·h respectively after 800 mg; t1/2 was 1.3 to 5.2 h. After 10 days dosing, plasma 447C88 concentrations were higher in the evening than the morning probably due to administration of the evening dose with more food. There were no significant changes in plasma triglcerides or total, LDL- or HDL-cholesterol after dosing with 447C88.
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  • 188
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1996), S. 293-298 
    ISSN: 1432-1041
    Schlagwort(e): Budesonide ; enema ; pharmacokinetics ; healthy subjects ; hepatic bypass
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The pharmacokinetics and systemic availability of budesonide after rectal administration of two single enema doses (2 mg in 100 ml fluid of almost identical composition) were compared in 15 healthy volunteers. In 11 of these subjects, 2 mg oral budesonide in a gelatine capsule was given on a separate occasion. An intravenous administration (0.5 mg) was given as reference. With this design, individual hepatic bypass of the rectally administered budesonide dose could be estimated. The pharmacokinetics of the two enema formulations were similar, although not bioequivalent. Mean systemic availability was 16% (range 4.2–43%) and 15% (3.2–50%) after rectal administration and 6.3% (2.4–10%) after oral administration. The rectal data revealed a small intra- but a substantial inter-subject variability in systemic availability. Cmax was 3.3 nmol·l-1 (0.95–8.2), 3.0 nmol·l-1 (0.64–8.9) and 1.3 nmol·l-1 (0.61–3.0), respectively, for the three formulations. Absorption was rapid and essentially terminated within 3 h after rectal dosing [tmax=1.3 h for both formulations (range 0.5–2.0)], but was slower after oral dosing [tmax=2.1 h (1.0–6.0)]. If a complete absorption after oral and rectal dosing is assumed, the fraction of the rectal dose entering the liver at first pass can be calculated to be 88% (55–99%). The higher systemic availability and intersubject variability after rectal dosing does not seem to be caused by differences in first-pass liver metabolism but rather by hepatic bypass of a varying portion of administered drug. This portion seems to be typical for an individual and might be explained by anatomical differences between subjects.
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  • 189
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 49 (1996), S. 317-323 
    ISSN: 1432-1041
    Schlagwort(e): Magnesium ; Plasma level ; pharmacokinetics ; bioavailability ; circadian fluctuation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Magnesium plasma concentrations were measured in healthy probands before and after administration of trimagnesium dicitrate by the oral and intravenous routes. There was a notable circadian fluctuation of the plasma concentration with a peak in the evening hours. After oral administration of 12 and 24 mmol magnesium, a long-lasting, statistically significant increase in plasma magnesium concentration measured as the increase in area under the curve (AUC) between 0 and 12 h, of 3.1% and 4.6%, respectively, was found. After intravenous administration of 4 and 8 mmol magnesium, AUCs increased by 9.5% and 16.1%, respectively. The decline in the plasma magnesium concentration after i.v. administration was compatible with a three-compartment model with a terminal half-time of about 8 h. Although no absolute value of the oral bioavailability of trimagnesium dicitrate could be determined from the data, our results may be important in helping to elucidate the influence of magnesium preparations on the plasma magnesium concentration. By comparing the effects of different preparations, it should be possible to estimate the relative oral bioavailability and the bioequivalence of these preparations.
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  • 190
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 5 (1972), S. 58-61 
    ISSN: 1432-1041
    Schlagwort(e): Pralidoxime chloride ; pharmacokinetics ; anti-cholinesterase poisoning
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary A dose of 1.0 g (10.0–14.0 mg/kg body weight) of pralidoxime mixed with various cholinolytics was given by i.m. injection to 29 healthy male subjects. A concentration of pralidoxime in blood of 4 µg/ml was reached after 5 to 10 min with all the mixtures and was maintained for about 1 to 2 h. The calculated half lives of pralidoxime in three groups of subjects were 62.2, 60.0 and 61.8 min., respectively. — The urinary excretions of pralidoxime during the first 4 h after the injections averaged 75.0, 79.6 and 69.6 per cent, respectively, of the total amount given. — The results are compared with published information about similar oximes.
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  • 191
    ISSN: 1432-1041
    Schlagwort(e): Key words Tolcapone ; Elderly; levodopa ; pharmacokinetics ; pharmacodynamics ; multiple-dose
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract. Objective: The purpose of this study was to assess the multiple-dose clinical pharmacology of tolcapone, a novel catechol-O-methyltransferase (COMT) inhibitor, in elderly subjects. Methods: The drug was administered orally t.i.d. for 7 days to four sequential groups of eight elderly subjects (gender ratio1:1) at doses of 100, 200, 400 and 800 mg in a double-blind, randomised, placebo-controlled, ascending-multiple-dose design. On days 2 and 7, a single dose of levodopa/benserazide 100/25 mg was given 1 h after the first intake of tolcapone. Plasma concentrations of tolcapone, its metabolite 3-O-methyltolcapone, levodopa and 3-O-methyldopa were determined during the course of the study in conjunction with COMT activity in erythrocytes. Results: Tolcapone was well tolerated at all dose levels, with a slight increase in gastrointestinal adverse events in females at higher doses. The drug was rapidly absorbed and eliminated and showed no changes in pharmacokinetics with time during multiple doses of 100 and 200 mg t.i.d. At doses of 400 and 800 mg t.i.d., tolcapone accumulated moderately as reflected in increased Cmax and AUC values. Despite the long half-life of 3-O-methyltolcapone (39 h), only minor accumulation occurred due to suppression of its formation by tolcapone. The pharmacodynamics of tolcapone did not change during the week of treatment as reflected in inhibition of COMT activity in erythrocytes, the derived parameters of the plasma concentration-effect relationship (inhibitory Emax model with constant EC50 values) and the effect on levodopa pharmacokinetics (1.6 to 2.5-fold increase in bioavailability). This suggests the absence of tolerance development and the insignificance of the altered pharmacokinetics at 400 and 800 mg t.i.d. with regard to the pharmacodynamics. Conclusion: The results of this study offer promising perspectives for the application of tolcapone as adjunct therapy to levodopa in the treatment of Parkinson’s disease.
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  • 192
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 50 (1996), S. 57-62 
    ISSN: 1432-1041
    Schlagwort(e): Key words Cilazapril ; Caucasians ; Chinese; cilazaprilat ; pharmacokinetics ; pharmacodynamics ; ACE inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract. Methods: The pharmacokinetics and pharmacodynamics of the angiotensin converting enzyme (ACE) inhibitor cilazapril were studied in 12 Chinese and 13 Caucasian, healthy, normotensive volunteers on their normal diet. Cilazapril was given orally as a single 2.5 mg capsule. Plasma was sampled for assay of the active metabolite, cilazaprilat, plasma renin activity (PRA), aldosterone, angiotensin I (AI) and ACE-activity. Plasma concentrations of the active drug were measured by radioimmunoassay. Blood pressure and heart rate were measured at regular intervals. Results: The pharmacokinetic parameters of cilazaprilat were similar in the two ethnic groups. No significant difference in plasma concentrations was found at any of the time points. However, the weight-adjusted plasma clearance was significantly higher in the Chinese group, which is compatible with their lower body weight. The effects on plasma hormones were also comparable, although there was a somewhat greater rise in PRA and greater fall in aldosterone levels in Chinese than in Caucasians. The effect of cilazapril on blood pressure and heart rate was greater than was previously reported in healthy volunteers. Systolic (SBP) and diastolic (DBP) blood pressure were significantly reduced in both groups, but there was a more prolonged reduction in DBP in Caucasians. In addition, heart rate (HR) was significantly increased from baseline from 5 h onwards in Chinese subjects and significantly higher in comparison with Caucasians at most time points from 1.5 h onwards. The pharmacokinetic parameters of cilazapril were essentially the same in healthy, normotensive Chinese and Caucasians. Cilazapril reduced blood pressure acutely in both groups, with good tolerance. The inhibition of ACE in relationship to time and the plasma concentrations of cilazaprilat were similar in the two groups, although the changes in PRA and aldosterone suggest an ethnic difference in the responses of the renin-angiotensin-aldosterone system.
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  • 193
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 50 (1996), S. 203-208 
    ISSN: 1432-1041
    Schlagwort(e): Key words Cyclosporine ; Felodipine; dehydrofelodi-pine ; pharmacokinetics ; blood pressure ; drug interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: In a double blind, randomised, placebo-controlled, cross-over study 12 healthy male volunteers were allocated to receive felodipine + placebo, cyclosporine + placebo, and felodipine + cyclosporine in order to investigate the interaction between the calcium channel blocker felodipine and cyclosporine as it affects the pharmacokinetics of felodipine, dehydrofelodipine, and cyclosporine, and 24-hour blood pressure measurements. Methods: Single doses of cyclosporine (capsules, 5 mg/kg body weight) and of felodipine (extended release (ER) tablets 10 mg) were given at a 1–2 week interval. Plasma drug concentrations were followed for 2 days after drug intake. Results: For cyclosporine, Cmax was increased after combined treatment (16%) compared to cyclosporine alone, but felodipine did not influence other kinetic parameters of cyclosporine. For felodipine, combined treatment with cyclosporine and felodipine increased AUC and Cmax (58% and 151%, respectively) and lowered mean residence time (24%) significantly compared to felodipine alone. For the metabolite dehydrofelodipine, too, AUC and Cmax were increased after the combined treatment (43% and 94%, respectively). Mean 24-hour systolic and diastolic blood pressures were significantly lower after felodipine, both when felodipine was given alone (121/68 mmHg) and in combination with cyclosporine (122/68 mmHg) compared to cyclosporine alone (127/73 mmHg). Conclusion: A combined single dose of cyclosporine and felodipine in healthy subjects increased the AUC and Cmax of felodipine suggesting a cyclosporine-induced decrease in the first-pass metabolism of felodipine, whereas the AUC of cyclosporine was only slightly increased by felodipine.
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  • 194
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 50 (1996), S. 221-223 
    ISSN: 1432-1041
    Schlagwort(e): Key words Oxybutynin; effect of food ; N-desethyl oxybutynin ; bioavailability ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The effect of food on the bioavailability of oxybutynin was assessed in a randomised cross-over study in 23 healthy volunteers. A single oral 10 mg dose of a controlled release oxybutynin tablet was administered after a high fat breakfast and to fasting subjects. The AUC, Cmax, tmax, t1/2 and MRT of oxybutynin and its active metabolite N-desethyloxybutynin were determined. Results: Breakfast did not change the AUC of oxybutynin but increased the AUC of N-desethyloxybutynin by about 20% . The Cmax of oxybutynin and N-desethyl oxybutynin were two-fold higher when the drug was administered after breakfast compared to the fasting state. Conclusion: Breakfast significantly reduced the MRT of oxybutynin and N-desethyloxybutynin.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 195
    ISSN: 1432-1041
    Schlagwort(e): Key words Felodipine ; Dietary interaction ; Flavonoids; pharmacodynamics ; pharmacokinetics ; grapefruit juice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To examine the effect of grapefruit juice on the metabolism of felodipine following intravenous and oral administration. Methods: The study had a randomised, four-way, crossover design in 12 healthy males. Single doses of felodipine were given as an intravenous infusion for 1 h (1.5 mg) or as an oral extended release (ER) tablet (10 mg). Grapefruit juice (150 ml) or water was ingested 15 min prior to drug intake. Results: Intake of grapefruit juice did not significantly alter the intravenous pharmacokinetics of felodipine compared to control treatment, whereas after oral drug administration it did lead to an increase in the mean AUC and Cmax by 72% and 173%, respectively, and the mean absolute bioavailability was increased by 112%. The fraction of the oral felodipine dose reaching the portal system was increased from 45% to 80% when intake of drug was preceded by grapefruit juice ingestion. The pharmacokinetics of the primary metabolite, dehydrofelodipine, was affected by the intake of juice, resulting in a 46% increase in Cmax. Juice intake immediately before oral felodipine resulted in more pronounced haemodynamic effects of the drug as measured by diastolic blood pressure and heart rate. However, the haemodynamic effects of the intravenous administration were not altered by juice intake. Vascular-related adverse events were reported more frequently when oral drug administration was preceded by juice intake compared with control treatment. Taking grapefruit juice immediately prior to intravenous felodipine administration did not cause any alteration in the adverse event pattern. Conclusion: The main acute effect of the grapefruit juice on the plasma concentrations of felodipine is mediated by inhibition of gut wall metabolism.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 196
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 52 (1997), S. 307-310 
    ISSN: 1432-1041
    Schlagwort(e): Key words Artemether ; Thai males; malaria ; dihydroartemisinin ; pharmacokinetics ; bioavailability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The pharmacokinetics and bioavailability of artemether and dihydroartemisinin were investigated in eight Thai males following the administration of single oral and intramuscular doses of artemether (300 mg) in a randomized two-way cross-over study. Results: Both oral and intramuscular artemether were well-tolerated. In most cases, artemether and dihydroartemisinin were detected in plasma after 30 min and declined to levels below the limit of detection within 18–24 h. Compared with intramuscular administration, oral administration of artemether resulted in a relatively rapid but incomplete absorption [Cmax: 474 vs 540 ng · ml−1; t max: 2.0 vs 3.9 h; AUC: 2.17 vs 5.20 μg · h · ml−1]. Geographic means of lag-time and absorption half-life (t 1/2a) of oral vs intramuscular artemether were 0.28 and 1.1 h vs 0.30 and 2 h, respectively. t 1/2z was significantly shortened after the oral dose [2.8 vs 6.9 h]. Mean oral bioavailability relative to intramuscular administration was 43.2%. The ratio of the AUCs of artemether to dihydroartemisinin was significantly lower after the oral than after the intramuscular dose (geometric mean: 0.29 vs 0.60).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 197
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 52 (1997), S. 403-406 
    ISSN: 1432-1041
    Schlagwort(e): Key words Oxybutynin ; Itraconazole; N-desethyloxy‐butynin; drug interaction ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: Oxybutynin has low oral bioavailability due to an extensive presystemic metabolism. It has been suggested that the biotransformation of oxybutynin is dependent on CYP3A. Because itraconazole, a widely used mycotic, is a potent inhibitor of CYP3A4, we wanted to study a possible interaction between oxybutynin and itraconazole. Methods: In this double-blind, randomized, two-phase cross-over study, ten healthy volunteers received either 200 mg itraconazole or placebo for 4 days. On day 4, each volunteer ingested a single dose of 5 mg oxybutynin. Serum concentrations of oxybutynin, its active metabolite N-desethyloxybutynin, and itraconazole were monitored over 24 h. Results: Itraconazole significantly increased both the area under the serum drug concentration-time curve (AUC0–t) and the peak concentration of oxybutynin twofold. The AUC0–t and the peak concentration of N-desethyloxybutynin were not significantly affected by itraconazole. Itraconazole did not change the peak time or the elimination half-life of either oxybutynin or N-desethyloxybutynin. The occurrence of adverse events after oxybutynin administration was not increased by itraconazole. Conclusions: Itraconazole moderately increases serum concentrations of oxybutynin, probably by inhibiting the CYP3A-mediated metabolism. However, the concentrations of N-desethyloxybutynin were practically unchanged. Since about 90% of the antimuscarinic activity of oxybutynin is attributable to N-desethyloxybutynin, any interaction of oxybutynin with CYP3A4 inhibiting drugs has only minor clinical significance.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 198
    ISSN: 1432-1041
    Schlagwort(e): Key words Idebenone; mitochondrial encephalomyopathy ; young patients ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The pharmacokinetics and tolerance of idebenone after single or repeated doses have been studied in young patients with mitochondrial encephalomyopathy. Results: No significant adverse effects were noted. In 3 out of 7 patients idebenone induced overall stimulation and improvement in arousal. Plasma concentrations of idebenone and its main metabolites were determined and the pharmacokinetic parameters of idebenone after single and repeated doses were estimated. During the single dose study, the mean plasma concentrations of idebenone and its main metabolites and mean pharmacokinetic parameters were comparable to published results (Cmax = 452.2 ng ⋅ ml−1, tmax = 2.3 h, AUC = 26 μg ⋅ ml−1 ⋅ h, t1/2β = 16.5 h). During the repeated doses study, no significant difference was found between mean residual plasma concentrations of idebenone on Day 2 (47 ng ⋅ ml−1) and Day 5 (70.6 ng ⋅ ml−1), and mean t1/2β of idebenone after the single and after repeated dose studies, i.e., there was no evidence of accumulation. Although idebenone did not appear to accumulate during this study, the coadministration of anticonvulsants, often prescribed during mitochondrial encephalomyopathy, can affect its pharmacokinetics.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 199
    ISSN: 1432-1041
    Schlagwort(e): Key words Amisulpride; ethanol vector ; performance ; memory ; cognitive function ; interaction ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objectives: Amisulpride is a benzamide antipsychotic that binds selectively to dopamine D2- and D3-receptors, preferentially in limbic and hippocampal structures. Since other substituted benzamides have a limited or negligible interaction with alcohol on human performance, amisulpride was studied for this potential. Methods: In a randomised double-blind crossover study, 18 young, non-smoking men took single oral doses of placebo and amisulpride 50 mg and 200 mg, without and with ethanol (0.8 g ⋅kg−1) taken 30 min later. Objective performance tests and self-ratings were done at baseline and 1.5, 3.5 and 6.5 h after drug intake. Memory (immediate and delayed recall) was tested 2 h after dosing. Breath ethanol and the plasma concentrations of amisulpride and prolactin were measured. Three-way ANOVA + Newman-Keul tests were used for statistical analyses; interactions were confirmed by factorial contrast ANOVA. Results: Mean blood ethanol was 0.94, 0.62 and 0.26 g ⋅l−1 at the three test times. It produced significant impairment in all performance tests (symbol digit substitution, simulated driving, body sway, flicker fusion, tapping, nystagmus), reduced both immediate and delayed recall in memory tests, and caused subjective clumsiness, muzziness and mental slowness, mainly between 1.5 to 4.5 h after dosing. Amisulpride, 50 and 200 mg elevated plasma prolactin but had minimal or no effect on performance, attention and memory. The decreases in immediate free recall after the 50 mg dose and in delayed free recall after the 200 mg dose were slight. Amisulpride neither modified blood ethanol concentrations nor enhanced the detrimental effect of ethanol on skilled and cognitive performance; it slightly antagonised ethanol in the digit copying test. Ethanol did not modify the effect of amisulpride on plasma prolactin, and the plasma concentrations of amisulpride were little changed by ethanol. Conclusions: Amisulpride in single oral doses of 50 and 200 mg did not interact significantly with the effects of high, moderate or low concentrations of ethanol on human skilled and cognitive performance. The drugs did interact pharmacokinetically.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 200
    ISSN: 1432-1041
    Schlagwort(e): Key words Mefloquine; mefloquine enantiomers ; carboxylic acid metabolite ; blood concentrations ; pharmacokinetics ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To compare concentrations of the separate enantiomers of mefloquine (MQ), total racemic MQ and the carboxylic acid metabolite in different blood fractions at steady state. Setting: Human volunteer laboratory, Unit of Clinical Pharmacology, Karolinska Institute. Volunteers: Ten healthy adult Caucasian volunteers. Methods: Drug concentrations were determined by high-performance liquid chromatography (HPLC). Results: Trough concentrations of the (+)RS enantiomer were higher in venous whole blood than in plasma and serum (mean ratios, 1.41 and 1.38). For the other enantiomer, (−)SR, concentrations were lower in whole blood than in plasma (mean ratio 0.89) and for the metabolite this ratio was 0.5. Conclusion: Stereoselective distribution might be important for antimalarial activity and should be considered when pharmacokinetic studies are performed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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