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1

Digitale Medien

Pharmacokinetics of sodium valproate in epileptic patients: Prediction of maintenance dosage by single-dose study (1980)

Schapel, G. J. ; Beran, R. G. ; Doecke, C. J. ; [weitere]

Springer

European journal of clinical pharmacology 17 (1980), S. 71-77

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ISSN: 1432-1041

Schlagwort(e): sodium valproate ; epileptic patients ; pharmacokinetics ; plasma concentration ; prediction ; maintenance dosage

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary Pharmacokinetic analysis of the plasma valproic acid concentration-time course, following a single oral dose (600 mg) of sodium valproate, was performed in 20 epileptic patients as an aid to the prediction of a proper chronic dosage regimen. A simple one-compartment model was found inadequate to describe the drug concentration-time course in 15 of the 20 patients studied. The average elimination (β phase) half-life of 9 h was shorter than that previously reported in healthy subjects. The latter observation and the wide variation in plasma valproic acid clearance observed between patients (0.09–0.53 ml/kg/min) may have been related to its altered disposition by concomitant anticonvulsant therapy. Sodium valproate maintenance therapy, determined by single-dose pharmacokinetic prediction of steady-state plasma valproic acid levels, did not require dosage adjustment because of unwanted effects. However, the occurrence of drug-related adverse events led to dosage reduction in 4 of 9 patients whose chronic therapy was not pharmacokinetically predicted. Moreover, the pharmacokinetic variability demonstrated for sodium valproate by patients on multiple therapy, whose chronic sodium valproate therapy was pharmacokinetically predicted, indicates the value of monitoring plasma valproic acid levels for the regulation of anticonvulsant therapy.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00561679

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2

Digitale Medien

Metabolic and haemodynamic effects and pharmacokinetics of a new selective beta1-adrenoceptor agonist, prenalterol, in man (1980)

Rönn, O. ; Fellenius, E. ; Graffner, C. ; [weitere]

Springer

European journal of clinical pharmacology 17 (1980), S. 81-86

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ISSN: 1432-1041

Schlagwort(e): prenalterol ; beta1-adrenoceptor agonist ; metabolic effects ; pharmacokinetics

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary The metabolic and haemodynamic effects of three intravenous doses (0.5, 1.0 and 4.0 mg) of prenalterol, a selective β1-adrenoceptor agonist, were studied in 10 healthy male subjects. Plasma levels of prenalterol during the experiments were related to the haemodynamic effects. Prenalterol induced a dose-dependent increase in systolic blood pressure and heart rate. The maximal effects amounted to about 30 mm Hg and 15 beats/min, respectively, after the highest dose (4.0 mg). The diastolic blood pressure fell by a maximum of about 15 mm Hg. The effect of prenalterol on systolic blood pressure and heart rate persisted for about 3 h after the end of the last infusion, whereas that on diastolic blood pressure only lasted for 60 min. Compared with placebo, there was a moderate increase in plasma FFA and glycerol. A small rise in insulin level was also recorded, but no significant change was seen in other metabolic variables — triglycerides, glucose, lactate, pyruvate. Serum potassium tended to decrease and serum sodium was unchanged. The initial distribution of prenalterol was rapid (half-life 7 min) and the overall elimination rate corresponded to a plasma half-life of 2 h. A linear relationship was found between the plasma level of prenalterol and its effects on systolic blood pressure and heart rate.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00562614

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3

Digitale Medien

Pharmacokinetics of zimelidine (1980)

Brown, D. ; Scott, D. H. T. ; Scott, D. B. ; [weitere]

Springer

European journal of clinical pharmacology 17 (1980), S. 111-116

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ISSN: 1432-1041

Schlagwort(e): zimelidine ; norzimelidine ; antidepressants ; pharmacokinetics ; bioavailability

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary The systemic availability of a new antidepressant, zimelidine, and of its pharmacologically active metabolite, norzimelidine, was studied in six healthy male volunteers. Three single doses of zimelidine (25 mg and 100 mg orally and 25 mg i.v.) and two single doses of norzimelidine (25 mg orally and i. v.) were given to each volunteer allowing at least seven days between administrations. Plasma concentrations of zimelidine and norzimelidine were determined in serial blood samples by HPLC. Following oral zimelidine peak plasma concentrations of the metabolite were attained about 3 h after dosing. Oral administration of norzimelidine itself resulted in a plasma concentration profile for this compound that was similar to that observed after oral zimelidine. Utilising the plasma concentration data following intravenous infusion of each compound, the elimination half-lives for zimelidine and norzimelidine were calculated to be 5.1 h (range 4.3–6.0) and 15.5 h (range 10.6–22.9) respectively. The total body clearances of the 2 compounds were similar at 0.52 l · min−1 (range 0.26–0.70) for zimelidine and 0.56 l · min−1 (range 0.28–0.83) for norzimelidine. The substantially longer elimination half-life of norzimelidine was apparently the result of a larger volume of distribution (9.4 l · kg−1; range 7.8–11.4) for this metabolite, as compared to zimelidine (3.21 · kg−1; range 1.6–4.9). The calculated bioavailability of zimelidine was 26% (range 9.1–39) after the 25 mg oral dose, and 29% (range 14–46) after the 100 mg dose. The bioavailability of norzimelidine was 66% (range 36–91). However, oral administration of zimelidine resulted in as much or more norzimelidine reaching the systemic circulation, as the oral administration of norzimelidine itself. This is important as a large part of the activity of the drug may be due to the metabolite.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00562618

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4

Digitale Medien

Plasma and salivary pharmacokinetics of dapsone estimated by a thin layer chromatographic method (1980)

Ahmad, R. A. ; Rogers, H. J.

Springer

European journal of clinical pharmacology 17 (1980), S. 129-133

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ISSN: 1432-1041

Schlagwort(e): dapsone ; salivary drug elimination ; pharmacokinetics ; acetylator phenotype

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary A high performance thin layer chromatographic assay for dapsone is described with a minimum level of detection of 20 ng ml−1 which is suitable for the study of dapsone pharmacokinetics in plasma and saliva. 100 mg dapsone was administered orally to seven normal adult volunteers, the mean plasma pharmacokinetic parameters were: α=0.23 h−1; β=0.0236 h−1, and t1/2β=30.2 h. Dapsone is also eliminated into the saliva and the t1/2 may be determined via its estimation in saliva. It is 73% bound to plasma protein and the saliva/plasma concentration ratio was found to be 27%. In two subjects the free plasma dapsone concentration was identical to the simultaneous salivary dapsone concentration. Therefore the salivary dapsone concentration is a measure of the free plasma fraction of dapsone. Saliva/plasma dapsone concentration ratios show no time or concentration dependence and little inter-individual variation but are unsuitable for acetylator phenotype determination because monoacetyldapsone is not eliminated in the saliva.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00562621

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5

Digitale Medien

Pharmacokinetics of sotalol after chronic administration to patients with renal insufficiency (1980)

Berglund, G. ; Descamps, R. ; Thomis, J. A.

Springer

European journal of clinical pharmacology 18 (1980), S. 321-326

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ISSN: 1432-1041

Schlagwort(e): sotalol ; hypertension ; renal impairment ; chronic administration ; pharmacokinetics

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary Ten hypertensive patients with moderate to severe impairment of renal function were treated with sotalol for 5 to 10 weeks (average 6.4 weeks). Dosage was individually titrated (range 80 to 480 mg daily). The drug was given once daily in the morning. In eight patients blood pressure was satisfactorily controlled. Higher steady-state levels were observed than have been reported after similar doses in patients with normal renal function. The apparent first-order elimination rate constant and plasma clearance were significantly correlated with glomerular filtration rate. For an anuric patient, serum half-life was calculated to be 69 h. In relation to the raised plasma levels, side effects were uncommon. Since sotalol is excreted predominantly via the kidney, therapy in patients with impaired renal function should start with a low dose and any increase in dosage should be made carefully. As the anti-hypertensive effect does not appear to be correlated with the plasma level or with tolerance, adjustment of dose should be based on clinical response.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00561389

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6

Digitale Medien

Influence of cimetidine on the pharmacokinetics of desmethyldiazepam and oxazepam (1980)

Klotz, U. ; Reimann, I.

Springer

European journal of clinical pharmacology 18 (1980), S. 517-520

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ISSN: 1432-1041

Schlagwort(e): desmethyldiazepam ; oxazepam ; cimetidine ; hepatic elimination ; pharmacokinetics ; interaction

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary The pharmacokinetics of single oral doses of desmethyldiazepam 20 mg or oxazepam 50 mg were studied in 5 healthy volunteers under controlled conditions, before and following a 24 h pretreatment with cimetidine 200 mg×5. Cimetidine significantly impaired (p=0.03) the elimination of desmethyldiazepam, as shown prolongation of its elimination half-life from 51.7±21.9 h to 72.6±39.4 h (mean ± SD), and a decrease in total plasma clearance from 12.0±2.7 ml/min to 8.6±3.3 ml/min. The disposition of oxazepam was not affected. From these results, and recently published data on diazepam and chlordiazepoxide, it is concluded that cimetidine impairs the hepatic elimination of those benzodiazepines which are metabolized by phase I reactions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00874666

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7

Digitale Medien

Clinical pharmacokinetics of alcuronium chloride in man (1980)

Walker, Judy ; Shanks, C. A. ; Triggs, E. J.

Springer

European journal of clinical pharmacology 17 (1980), S. 449-457

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ISSN: 1432-1041

Schlagwort(e): alcuronium ; single dose ; multiple dose ; plasma levels ; neuromuscular response ; pharmacokinetics ; anaesthesia

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary The pharmacokinetic behaviour of alcuronium is described for nineteen patients undergoing anaesthesia for elective surgery. Eleven patients received a single bolus intravenous dose of 0.25 mg/kg, while 8 patients required additional doses of 0.125 mg/kg. A two-compartment open model was found to describe adequately both the single dose and multiple dose data for the majority of patients. No significant differences were found in the model-independent pharmacokinetic parameters between the single and multiple dose studies. Mean values for the pooled data for the half-life (t1/2β), apparent volume of distribution (Vdβ), volume of distribution at steady-state (Vdss), volume of the central compartment (Vc) and plasma clearance (Clp) were 198.75 min, 24.261, 20.891, 8.181 and 90.22 ml/min respectively. Evoked muscle twitch response was monitored in 17 of the patients to assess the degree of relaxant blockade. The bolus dose of alcuronium produced complete block in 9 patients and between 95 and 99% block in the remainder. The time of onset to maximum block ranged from 3 to 30 min with the concurrently measured plasma levels of alcuronium being 0.79 to 2.25 µg/ml. The time taken following bolus administration to 5% recovery (95% paralysis) was a mean of 42 min and the corresponding mean alcuronium plasma concentration was 0.78 µg/ml.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00570163

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8

Digitale Medien

Paracetamol pharmacokinetics in thyroid disease (1980)

Forfar, J. C. ; Pottage, A. ; Toft, A. D. ; [weitere]

Springer

European journal of clinical pharmacology 18 (1980), S. 269-273

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ISSN: 1432-1041

Schlagwort(e): paracetamol ; thyrotoxicosis ; hypothyroidism ; drug disposition ; pharmacokinetics

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary The absorption, distribution and elimination of oral paracetamol have been studied in patients before and after treatment of thyrotoxicosis (n=7) and hypothyroidism (n=4). Absorption was faster in patients with untreated thyrotoxicosis than when subsequently euthyroid. The peak paracetamol concentration, however, was lower in thyrotoxic patients due to an apparent increase in the total body clearance and a shorter plasma half-life. Both absorption and elimination rates were reduced in hypothyroid patients, but were not significantly different from the euthyroid results. When estimated using a two compartment model the total volume of distribution and the hybrid distribution rate constants were unrelated to thyroid status, but the apparent volume of the central compartment was significantly greater in the thyrotoxic group. These changes in drug disposition may contribute to differences in drug response seen in thyroid disease.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00563010

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9

Digitale Medien

Pharmacokinetic of 2-(p-methylallylaminophenyl) propionic acid, alminoprofene, in man after single and multiple oral doses (1980)

Premel-Cabic, A. ; Allain, P. ; Pidhorz, L. ; [weitere]

Springer

European journal of clinical pharmacology 18 (1980), S. 419-422

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ISSN: 1432-1041

Schlagwort(e): alminoprofene ; antalgic ; pharmacokinetics ; single dose ; multiple doses

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary 2-(p-methylallylaminophenyl) propionic acid, alminoprofene (INN), a new antalgic drug, was administered orally to men as a single (300 mg) and multiple doses (300 mg three times daily). Plasma and urine concentrations of alminoprofene were determined by gas-liquid chromatography. After the single oral dose, the peak plasma level (36.2 to 41.5 mg/l) was reached within 0.5–1.5 h. The biological half-life ranged from 2.5 to 3.2 h. During chronic administration of alminoprofene, steady-state equilibrium quilibrium was etablished within 24 h. The urinary excretion of alminoprofene as unchanged product and as glucuronide was very important.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00636796

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10

Digitale Medien

Pharmacokinetics and oral bioavailability of pyridostigmine in man (1980)

Aquilonius, S. -M. ; Eckernäs, S. -Å. ; Hartvig, P. ; [weitere]

Springer

European journal of clinical pharmacology 18 (1980), S. 423-428

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ISSN: 1432-1041

Schlagwort(e): pyridostigmine ; myasthenia gravis ; pharmacokinetics ; bioavailability ; plasma levels

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Medizin

Notizen: Summary The pharmacokinetics of pyridostigmine was evaluated after intravenous injection in two healthy male volunteers and after oral administration to five subjects. Plasma concentrations of pyridostigmine were determined after ion pair extraction from plasma and analysis by gas chromatography — mass spectrometry with chemical ionization, using d6-pyridostigmine as internal standard. Degradation of pyridostigmine in vitro was compensated for by use of the deuterated internal standard and by rapid cooling and separation of plasma after blood sampling. After intravenous administration of pyridostigmine 2.5 mg the plasma elimination half-life was 1.52 h, the volume of distribution was 1.43 l/kg and the plasma clearance 0.65 l/kg × h. The pharmacokinetic constants were very similar after oral administration of pyridostigmine 120 mg; the elimination half-life was 1.78±0.24 h, the volume of distribution 1.64±0.29 l/kg and the plasma clearance was 0.66±0.22 l/kg × h. The bioavailability was calculated to be 7.6±2.4%. When pyridostigmine was taken together with food, the time to reach the peak plasma concentration was prolonged from 1.7 to 3.2 h. Bioavailability, however, was not influenced by concomitant food intake. “Steady-state” plasma concentrations of pyridostigmine were measured in myasthenic patients on their ordinary dose schedule of cholinesterase inhibitor drugs. More than a seven-fold difference in steady-state plasma concentration was found between patients taking approximately the same daily dose of pyridostigmine.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00636797

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