Clorazepate kinetics in treated epileptics.

Area of Science:

• Pharmacokinetics
• Clinical Pharmacology
• Epilepsy Treatment

Background:

• Clorazepate is a prodrug readily decarboxylated to desmethyldiazepam.
• Understanding desmethyldiazepam kinetics is crucial for optimizing therapy in epileptic patients.

Purpose of the Study:

• To investigate the pharmacokinetics of desmethyldiazepam after single and multiple oral doses of clorazepate in epileptic patients.
• To compare drug metabolism in epileptic patients undergoing treatment with pharmacokinetic data from healthy individuals.

Main Methods:

• Single and multiple oral doses of clorazepate administered to epileptic patients.
• Serum concentrations of desmethyldiazepam measured over time.
• Pharmacokinetic parameters analyzed using a two-compartment open model.

Main Results:

• Peak serum desmethyldiazepam concentrations observed within 0.5 to 1 hour, indicating rapid absorption.
• Apparent half-life of the distribution phase was 1.28 ± 0.44 hr, and the disposition phase was 40.8 ± 9.96 hr.
• Total plasma clearance (34.4 ± 7.2 ml/min) was higher in treated epileptics than in normals, suggesting increased hepatic metabolism.

Conclusions:

• Rapid absorption necessitates divided daily dosing of clorazepate to manage high serum desmethyldiazepam levels.
• Hepatic metabolism of desmethyldiazepam is significantly greater in epileptic patients with multiple drug exposures.
• Extrapolating pharmacokinetic data from healthy individuals to patients with polypharmacy can be misleading.