Effect of piperine on CYP2E1 enzyme activity of chlorzoxazone in healthy volunteers

1. The purpose of the present study was to investigate the effect of piperine (PIP) on CYP2E1 enzyme activity and pharmacokinetics of chlorzoxazone (CHZ) in healthy volunteers.2. An open-label, two period, sequential study was conducted in 12 healthy volunteers. A single dose of PIP 20 mg was administered daily for 10 days during treatment phase. A single dose of CHZ 250 mg was administered during control and after treatment phases under fasting conditions. The blood samples were collected at predetermined time intervals after CHZ dosing and analyzed by HPLC.3. Treatment with PIP significantly enhanced maximum plasma concentration (Cmax) (3.14–4.96 μg/mL), area under the curve (AUC) (10.46–17.78 μg h/mL), half life (T1/2) (1.26–1.82 h) and significantly decreased elimination rate constant (Kel) (0.57–0.41 h − 1), apparent oral clearance (CL/F) (24.76–13.65 L/h) of CHZ when compared to control. In addition, treatment with PIP significantly decreased Cmax (0.22–0.15 μg/mL), AUC (0.94–0.68 μg h/mL), ...