Darunavir/cobicistat, sold under the brand names Prezcobix (US) and Rezolsta (EU), is an antiretroviral medication used to treat and prevent HIV/AIDS. It is a fixed dose combination drug containing 800 mg of darunavir and 150 mg of cobicistat. Darunavir is an HIV protease inhibitor and cobicistat increases the effectiveness of darunavir by blocking its metabolism by the enzyme CYP3A.