Drug Interaction Report

MONITOR: Orlistat may theoretically reduce the gastrointestinal absorption and therapeutic efficacy of antiretroviral agents. The mechanism may involve retention of lipophilic medicines in the gastrointestinal tract or reduced gastrointestinal tract transit time. Data have been reported for efavirenz and lopinavir. Other antiretroviral agents may also be affected.

MANAGEMENT: The potential reduction in antiretroviral efficacy should be considered before initiating treatment with orlistat. Patients who take antiretroviral medications should be advised to consult their physician before using the non-prescription brand of orlistat.

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.