Indinavir is primarily used as an antiretroviral medication in the treatment of HIV infection. It belongs to the class of protease inhibitors, which work by blocking the activity of the HIV protease enzyme. This enzyme is crucial for the virus to replicate and produce infectious particles. By inhibiting this enzyme, indinavir helps reduce the viral load in the body and slows the progression of HIV to AIDS. It is often prescribed as part of a combination therapy, known as highly active antiretroviral therapy (HAART), to enhance its effectiveness and minimize the risk of developing drug resistance. Patients taking indinavir must adhere to a strict dosing schedule and maintain adequate hydration to reduce the risk of kidney stones, a known side effect of the medication.