Optimizing concentrations of concomitant antiretrovirals by reducing etravirine doses: two case reports of complex drug-drug interactions.

We report the cases of two treatment-experienced HIV-infected patients with complex antiretroviral regimens that showed significant drug-drug interactions with etravirine. Unexpectedly high etravirine concentrations likely caused subtherapeutic levels of darunavir, elvitegravir and dolutegravir through concentration-dependent metabolic induction. Therapeutic drug monitoring allowed safe etravirine dose decreases to manage these interactions.