Fosamprenavir is primarily used in the treatment of HIV infection. It works as a prodrug of amprenavir, which means it is converted into amprenavir in the body. Once activated, it inhibits the HIV protease enzyme, preventing the virus from replicating and spreading. This helps to reduce the viral load in patients and improves immune system function. It is often prescribed as part of combination antiretroviral therapy (ART) to enhance its effectiveness and minimize the risk of drug resistance. Fosamprenavir is particularly useful for patients who have difficulty adhering to complex medication regimens due to its convenient dosing schedule. It is also studied for its potential use in pediatric HIV cases, offering a treatment option for younger patients.