fosamprenavir + lopinavir + ritonavir

Fosamprenavir, lopinavir, and ritonavir are antiretroviral drugs used in combination for the treatment of human immunodeficiency virus (HIV) infection. All three agents are protease inhibitors. Fosamprenavir is a prodrug of amprenavir and inhibits HIV-1 protease, preventing viral polyprotein cleavage and resulting in immature, noninfectious viral particles[1][5]. Lopinavir is a potent inhibitor of HIV-1 protease; its antiviral activity prevents maturation of the virus by blocking the production of mature infectious virions[6]. Ritonavir acts primarily as a pharmacokinetic enhancer by inhibiting cytochrome P450 3A-mediated metabolism, thereby increasing plasma concentrations of other protease inhibitors such as lopinavir and fosamprenavir[2][6]. The combination may be considered in treatment-experienced patients but can result in significant drug-drug interactions that reduce exposure to both amprenavir (the active form of fosamprenavir) and lopinavir[8].