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  • 1
    ISSN: 1432-2072
    Keywords: Risperidone ; Pharmacokinetics ; Elderly ; Renal disease ; Liver disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pharmacokinetics of the antipsychotic agent risperidone were investigated in healthy young and elderly subjects, cirrhotic patients and patients with moderate and severe renal insufficiency. In a comparative trial, a single oral 1-mg dose was administered to fasting subjects. Plasma and urine concentrations of the parent compound risperidone and the active moiety (i.e. risperidone plus 9-hydroxy-risperidone) were measured by radioimmunoassays. No or only small changes in plasma protein binding were observed in hepatic and renal disease, whereas the protein binding was not influenced by aging. The inter-individual variability in plasma concentrations of the active moiety was much less than the variability in plasma concentrations of risperidone. Three out of six subjects, behaving like poor metabolizers, were on medication (thiethylperazine, amitriptyline, metoprolol) that may inhibit risperidone metabolism by CYP2D6 (debrisoquine 4-hydroxylase). The pharmacokinetics of risperidone in elderly and cirrhotic patients were comparable to those in young subjects, whereas total oral clearance was reduced in renal disease patients. The elimination rate and clearance of 9-hydroxy-risperidone was reduced in elderly and renal disease patients because of a diminished creatinine clearance. The CLoral of the active moiety, which is primarily 9-hydroxy-risperidone, was reduced by about 30% in the elderly and by about 50% in renal disease patients. In addition, the t1/2 of the active moiety was prolonged (19 h in young subjects versus about 25 h in elderly and renal disease patients). Based upon the pharmacokinetics of the active moiety, a dose reduction and a cautious dose titration is advised in the elderly and in patients with renal disease. In cirrhotic patients, the single-dose pharmacokinetics were comparable to those in healthy young subjects.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 31 (1986), S. 339-342 
    ISSN: 1432-1041
    Keywords: ketanserin ; ketanserin-ol ; pharmacokinetics ; reduction-oxidation equilibrium ; healthy volunteers ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The metabolic reduction-oxidation equilibrium between ketanserin and ketanserin-ol was studied after oral dosing of both substances to two healthy volunteers. Comparison of plasma Cmax and AUCs indicated that the equilibrium was shifted towards ketanserin-ol. There is evidence that ketanserin-ol elimination is the slowest step dictating the terminal half-life of ketanserin.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Keywords: Key words Nebivolol ; Cardiovascular effects; pharma-cokinetics ; healthy volunteers ; obese subjects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The pharmacokinetics of a single i.v. dose of the new racemic β-adrenoceptor-blocker nebivolol [0.073 mg base · kg–1 ideal body weight (IBW)] was studied in 9 obese (157% IBW) and 9 non-obese healthy volunteers (98% IBW). Each group contained 4 men and 5 women, aged 32 years, including one poor hydroxylator (dextrometorphan test). Methods: The cardiovascular effects of nebivolol are significant decreases in systolic and diastolic blood pressure, heart rate and cardiac output, which last up to 4–5 h. The plasma concentrations of the separate d- and l- enantiomers of nebivolol, with and without hydroxylated metabolite, were measured by radioimmunoassay and the unchanged racemate by high-pressure liquid chromatography (HPLC). The pharmacokinetic parameters for each form were calculated separately. Results: The main pharmacokinetic parameters of unchanged nebivolol in extensive metabolizers were (controls): distribution volume at steady state (Vss) 673 l; volume corrected by real body weight (Vss · kg–1) 11.2 l ·  kg–1; total clearance (CL) 51.6 h–1; and terminal half-life (t1/2) 10.3 h. The Vss (898 l) and CL (71.6 l · h–1) were significantly higher in obese patients. But Vss · kg–1 (9.4 l · kg–1) and t1/2 (10.0 h) were not significantly different from those in controls. The CL was clearly reduced (15–18 l · h–1) and the t1/2 prolonged (32–34 h) in poor hydroxylators, in both control and obese subjects. The pharmacokinetic parameters of the separate unchanged enantiomers were similar to those of the racemate in both groups. The pharmacokinetics of l-nebivolol were more influenced by the hydroxylation phenotype than those of d-nebivolol. The trend of the results for the sum of each enantiomer plus its metabolite, was similar to those for the unchanged form. Conclusion: The distribution of nebivolol in the adipose tissue in obese subjects is limited, despite its high lipophilicity. The differences between obese and non-obese subjects were not clinically relevant.
    Type of Medium: Electronic Resource
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