| Etravirine is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with the advantages of in vitro potency against many strains of virus resistant to efavirenz and nevirapine, as well as a higher genetic barrier to resistance. Etravirine is indicated for use in treatment-experienced patients, and the approved dose in adults is 200 mg twice daily. Etravirine should be administered after a meal as bioavailability is significantly reduced when taken in the fasting state. Etravirine is a substrate of CYP3A4, CYP2C9, CYP2C19, and uridine diphosphate glucuronyltransferase, and induces CYP3A4, weakly inhibits CYP2C9 and moderately inhibits CYP2C19. Etravirine may be coadministered with nucleoside/tide reverse transcriptase inhibitors, raltegravir and boosted darunavir, lopinavir, and saquinavir without dosage adjustment. Etravirine should not be given with other NNRTIs, unboosted protease inhibitors, and atazanavir/ritonavir, tipranavir/ritonavir, and fosamprenavir/ritonavir due to unfavorable drug interactions. In randomized, controlled trials, twice daily etravirine combined with darunavir/ritonavir plus optimized background therapy demonstrated better efficacy compared to darunavir/ritonavir plus optimized background therapy alone in treatment experienced populations out to 96 weeks follow-up. The main etravirine-associated toxicity is mild to moderate self-limiting rash, although severe and sometimes fatal hypersensitivity reactions have been reported. Etravirine offers a potent sequencing option after the development of resistance to first-line NNRTIs, and is a welcome addition to this established drug class. |
