atazanavir + ritonavir + lamivudine + zidovudine

Atazanavir + ritonavir + lamivudine + zidovudine is a fixed-dose combination of four antiretroviral agents used in the treatment of HIV-1 infection. Atazanavir is an HIV-1 protease inhibitor that prevents viral polyprotein cleavage, resulting in immature, non-infectious viral particles. Ritonavir acts as both a protease inhibitor and a pharmacokinetic enhancer by inhibiting CYP3A4-mediated metabolism, thereby increasing plasma concentrations of atazanavir. Lamivudine and zidovudine are nucleoside reverse transcriptase inhibitors (NRTIs) that inhibit reverse transcriptase, blocking the conversion of viral RNA into DNA and thus preventing replication. This combination targets multiple stages of the HIV replication cycle to reduce viral load, slow disease progression, enhance immune response, improve efficacy, prevent resistance development, and simplify dosing for better adherence[1][6][4].