Drug Interaction Report

Coadministration with ranitidine may slightly reduce the plasma concentrations of etravirine. The mechanism of interaction has not been described. In 18 study subjects administered etravirine with ranitidine 150 mg twice a day, etravirine peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 6% and 14%, respectively. These changes are not considered clinically significant. Etravirine and ranitidine may be coadministered without any dosage adjustments.

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.

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.