Once-daily atazanavir/ritonavir compared with twice-daily lopinavir/ritonavir, each in combination with tenofovir and emtricitabine, for management of antiretroviral-naive HIV-1-infected patients: 96-week efficacy and safety results of the CASTLE study.

Background: Once-daily atazanavir/ritonavir demonstrated similar antiviral efficacy to twice-daily lopinavir/ritonavir over 48 weeks, with less gastrointestinal disturbance and a better lipid profile, in treatment-naive patients.

Methods: International, multicenter, open-label, 96-week noninferiority randomized trial of atazanavir/ritonavir 300/100 mg once daily vs lopinavir/ritonavir 400/100 mg twice daily, each in combination with fixed-dose tenofovir/emtricitabine 300/200 mg once daily, in antiretroviral-naive, HIV-1-infected patients. The primary end point was the proportion of patients with HIV RNA <50 copies/mL at 48 weeks.