Effect of rifampin, an inducer of CYP3A and P-glycoprotein, on the pharmacokinetics of risperidone.

Author(s): Kim KA, Park PW, Liu KH, Kim KB, Lee HJ, Shin JG, Park JY

Affiliation(s): Department of Clinical Pharmacology & Toxicology, Anam Hospital, Korea University College of Medicine, 126-1, Anam-dong 5-ga, Sungbuk-gu, Seoul 136-705, Korea.

Publication date & source: 2008-01, J Clin Pharmacol., 48(1):66-72.

Publication type: Randomized Controlled Trial; Research Support, Non-U.S. Gov't

The authors studied the effect of rifampin, a dual inducer of CYP3A and P-glycoprotein, on the pharmacokinetics and pharmacodynamics of risperidone in humans. Ten healthy male subjects were treated daily for 7 days with 600 mg rifampin or with placebo. On day 6, a single dose of 1 mg risperidone was administered. Plasma risperidone and 9-hydroxyrisperidone concentrations were measured. Rifampin significantly decreased the mean area under the plasma concentration-time curve by 51% for risperidone, by 43% for 9-hydroxyrisperidone, and by 45% for the active moieties (risperidone + 9-hydroxyrisperidone). Rifampin also decreased the peak plasma concentration of risperidone by 38%, 9-hydroxyrisperidone by 46%, and the active moieties by 41%. The apparent oral clearance of risperidone approximately doubled after rifampin treatment. Thus, rifampin reduced the exposure to risperidone, probably because of a decrease in its bioavailability through the induction of CYP3A and probably P-glycoprotein.