Fosamprenavir Calcium Salt is primarily used in the treatment of HIV infection. It functions as a prodrug of amprenavir, which means it is converted into amprenavir in the body. Amprenavir is a protease inhibitor that works by blocking the activity of the HIV protease enzyme, preventing the virus from replicating and spreading. This medication is often prescribed as part of a combination antiretroviral therapy (ART) to manage HIV-1 infection in adults and children. It helps reduce the viral load in the blood, improves immune system function, and slows the progression of the disease. The calcium salt form enhances its stability and bioavailability, making it more effective for oral administration. It is typically used in patients who have developed resistance to other protease inhibitors or as part of a tailored treatment regimen based on individual patient needs.