Used in the treatment of HIV infection as a protease inhibitor, Indinavir works by blocking the action of the HIV protease enzyme, preventing the virus from maturing and producing infectious particles. It is typically used in combination with other antiretroviral drugs as part of highly active antiretroviral therapy (HAART). This combination approach helps reduce viral load, maintain immune function, and slow the progression of HIV to AIDS. Indinavir is taken orally and requires strict dosing schedules, often with attention to fasting or specific food intake to ensure optimal absorption. Its use has declined over time due to the availability of newer agents with more convenient dosing and fewer side effects, but it played a significant role in early HIV treatment regimens.