Atazanavir/Ritonavir: A Valuable Once-Daily HIV Protease Inhibitor with Little Impact on Lipid Profile

Atazanavir is the first once-daily azapeptide HIV protease inhibitor that may offer simpler and safer protease inhibitor-based highly active antiretroviral therapy, as it has been associated with less hyperlipemia and diarrhea compared with the other drugs of the same class. The typical side effect of atazanavir is an asymptomatic increase in serum unconjugated bilirubin. Ritonavir-boosted atazanavir has proved to be effective in treatment-naive HIV-infected individuals, and there is no evidence that it leads to the selection of mutations conferring cross-resistance to other protease inhibitors. Its efficacy in patients harboring drug-resistant variants is not statistically different from that of the reference protease inhibitor, lopinavir/ritonavir. It has been approved by the US FDA for use in drug-experienced HIV-infected patients, although atazanavir/ritonavir-based regimens have now been included among those recommended by the International AIDS Society – USA Panel and the Department of Health and Human Services Panel as initial treatment. The aim of this article is to describe the pharmacological characteristics of atazanavir/ritonavir, and the results of the main clinical trials investigating the safety and efficacy of this antiretroviral combination.