fexofenadine and Rimactane Interactions

Interactions between fexofenadine and Rimactane (rifampin)

rifampin and fexofenadine (Moderate Drug-Drug)

MONITOR: The coadministration with rifampin may decrease the oral bioavailability of fexofenadine. The mechanism is rifampin induction of intestinal P-glycoprotein, resulting in increased secretion and decreased absorption of fexofenadine. In 24 healthy volunteers divided into 4 groups by age and gender, rifampin (600 mg orally once a day for 6 days) increased the oral clearance of fexofenadine (60 mg single oral dose) in the different groups by 87% to 169% compared to when fexofenadine was administered alone. Mean peak plasma concentration (Cmax) decreased by 32% to 51%, while terminal half-life and renal clearance were not affected. The effect of rifampin on fexofenadine pharmacokinetics was independent of age and sex.

MANAGEMENT: Patients treated with rifampin should be monitored for potentially diminished or inadequate therapeutic response to fexofenadine.