- Currently on a stable ART regimen for at least 16 consecutive weeks prior to study entry. Participants whose regimens have changed with respect to dose or formulation are eligible, but patients who have changed to different drugs in the same class are not eligible. Participants taking atazanavir must also be taking ritonavir or a ritonavir-boosted drug to be eligible for this study. More information on this criterion can be found in the protocol.