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: Food enhances the absorption and oral bioavailability of darunavir administered in combination with low-dose ritonavir. The mechanism is unknown. When administered with food, the peak plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) of darunavir were approximately 30% higher than when administered in the fasting state. Darunavir exposure was similar for the range of meals studied. The total caloric content of the various meals evaluated ranged from 240 Kcal (12 grams fat) to 928 Kcal (56 grams fat).

MANAGEMENT: To ensure maximal oral absorption, darunavir coadministered with ritonavir should be taken with food. The type of food is not important.