atazanavir + ritonavir + abacavir + lamivudine

This is a four-drug antiretroviral combination regimen consisting of atazanavir, ritonavir, abacavir, and lamivudine. It is used in the treatment of HIV-1 infection. Atazanavir is a protease inhibitor that blocks the activity of HIV-1 protease, preventing viral maturation. Ritonavir acts as a pharmacokinetic booster by inhibiting CYP3A-mediated metabolism of atazanavir, thereby increasing its plasma concentration and efficacy[3][10]. Abacavir and lamivudine are nucleoside reverse transcriptase inhibitors (NRTIs) that inhibit HIV reverse transcriptase by causing chain termination during viral DNA synthesis[5]. This combination has been shown to be effective and well-tolerated in antiretroviral-naïve patients with high rates of virologic suppression over 48 weeks[1]. The regimen leverages the complementary mechanisms of action from each drug class to achieve potent suppression of HIV replication.