Drug Interaction Report

Theoretically, coadministration with inducers of CYP450 3A4 and/or P-glycoprotein (P-gp) may decrease the plasma concentrations of rivaroxaban, which is a substrate of the isoenzyme as well as the efflux transporter. In a pharmacokinetic study, administration of a single 20 mg dose of rivaroxaban with the potent CYP450 3A4 and P-gp inducer rifampin (titrated up to 600 mg once daily) resulted in approximately 22% and 50% decreases in mean rivaroxaban peak plasma concentration (Cmax) and system exposure (AUC), respectively, with parallel decreases in its pharmacodynamic effects. The effects of less potent inducers of either CYP450 3A4 or P-gp have not been studied.

ADJUST DOSING INTERVAL: Coadministration with food increases the oral bioavailability of etravirine. The mechanism is unknown. Compared to administration following a meal, the systemic exposure (AUC) to etravirine was decreased by about 50% when the drug was administered under fasting conditions. The types of meal studied (ranging from 345 kilocalories containing 17 grams fat to 1160 kilocalories containing 70 grams fat) did not appear to make a difference with respect to impact on etravirine bioavailability.

MANAGEMENT: Etravirine should always be administered following a meal.