Used as a pharmacokinetic enhancer in antiretroviral therapy for HIV. It boosts the effectiveness of certain antiretrovirals, including HIV protease inhibitors (e.g., darunavir) and integrase inhibitors (e.g., elvitegravir), by inhibiting cytochrome P450 3A (CYP3A) enzymes in the liver and intestines, which slows the breakdown of co-administered drugs. This results in higher and more sustained blood levels of the active antiretrovirals, allowing for lower doses and less frequent dosing. Commonly combined with elvitegravir, tenofovir, and emtricitabine in single-tablet regimens. Not active against HIV itself but plays a critical supporting role in modern HIV treatment protocols.