Pharmacokinetics of pinazepam in healthy volunteers.
The kinetics of pinazepam were studied in six healthy male volunteers aged between 26 and 31 years. The drug was administered in a single oral dose (10 mg). The concentrations of the parent compound and metabolites were measured in the plasma and urine by gas-chromatographic analysis. Plasma levels of pinazepam were fitted to a two-compartment open model with first order absorption rate using a three-exponential equation. Absorption rate constant and peak plasma levels of pinazepam were 1.36 +/- 0.15 h-1 and 36.8 +/- 5.1 ng/ml respectively. Plasma decay of the drug consisted of an initial rapid elimination phase (alpha = 0.46 +/- 0.06 h-1) followed by a slow one (beta = 0.046 +/- 0.004 h-1). N-desmethyldiazepam was the only metabolite detected in the plasma. Its plasma concentrations were higher than those of the parent compound shortly after administration. Urine was collected for 72 h after dosing. Those specimens contained unconjugate pinazepam and N-desmethyldiazepam and glucuronated oxazepam and 3-OH-pinazepam. Only 0.016% of the pinazepam administered was recovered as unchanged compound in the urine.
D000328:Adult; D014151:Anti-Anxiety Agents / Q000378:metabolism*; D001569:Benzodiazepines; D001570:Benzodiazepinones / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008297:Male
D014151:Anti-Anxiety Agents; D001570:Benzodiazepinones; D001569:Benzodiazepines; C010763:pinazepam