Drug Interaction Report

Coadministration with inducers of uridine diphosphate glucuronosyltransferase (UGT) 1A1 may reduce the plasma concentrations of raltegravir, which is primarily metabolized by UGT1A1-mediated glucuronidation. In 9 study subjects, administration of a single 400 mg dose of raltegravir in combination with the potent UGT1A1 inducer rifampin (600 mg daily) resulted in a 38% decrease in raltegravir peak plasma concentration (Cmax), a 40% decrease in systemic exposure (AUC), and a 61% decrease in trough plasma concentration (Cmin) compared to administration of raltegravir alone. The impact of other potent inducers of drug-metabolizing enzymes such as carbamazepine, phenytoin, and phenobarbital on UGT1A1 is unknown. Other, less potent inducers (e.g., efavirenz, nevirapine, etravirine, rifabutin, St. John's Wort, pioglitazone) may be used with the recommended dosage of raltegravir.