Clinical perspective on antiretroviral drug–drug interactions with the non-nucleoside reverse transcriptase inhibitor etravirine

Etravirine is an effective and well-tolerated recently approved non-nucleoside reverse transcriptase inhibitor (NNRTI) for HIV type-1-infected patients with previous antiretroviral treatment experience. Considering the importance of combining antiretrovirals for their optimal use in treating HIV, a number of drug–drug interactions with etravirine and other antiretrovirals have been evaluated. Etravirine is a weak inducer of cytochrome P450 (CYP)3A and a weak inhibitor of CYP2C9/CYP2C19 and P-glycoprotein, and although etravirine is metabolized by the CYP enzyme system, the extent of clinically relevant interactions with other antiretrovirals is limited. Etravirine can be combined with all currently available nucleoside/nucleotide reverse transcriptase inhibitors without dose adjustments, but not with other NNRTIs. Available data indicate that etravirine can be coadministered with most of the currently available ritonavir-boosted HIV protease inhibitors. Coadministration with tipranavir/ritonavir or unboosted HIV protease inhibitors is not recommended because of clinically relevant changes in exposure to etravirine or the coadministered HIV protease inhibitor, respectively. Etravirine can be coadministered with the integrase inhibitors elvitegravir/ritonavir or raltegravir, and with the fusion inhibitor enfuvirtide, without dose adjustments. Dose adjustment of the C–C chemokine receptor type-5 antagonist maraviroc is required, with the type of adjustment depending on whether a boosted HIV protease inhibitor is included in the regimen. In conclusion, etravirine can be combined with most antiretrovirals, with no clinically meaningful effect on drug exposure or safety/tolerability profiles.