While many factors contribute to the success or failure of antiretroviral therapy for HIV, among the most important are factors that influence adherence to a treatment regimen, such as duration of therapy, dosing frequency, pill burden, side effects, and patient behaviors. Inconsistent adherence or nonadherence to antiretroviral therapy can result in suboptimal drug exposure. Suboptimal drug exposure can, in turn, impact short- and long-term patient outcomes by increasing the likelihood of drug resistant HIV mutants and subsequent virologic and clinical failure. It is therefore essential to design treatment regimens that promote long-term adherence to potent antiretroviral therapy. This study will evaluate the relative contribution of reduced-frequency dosing and directly observed therapy on the magnitude and durability of virologic suppression in patients treated with potent antiretroviral therapy.

Patients will be randomly assigned to one of three study arms. Arms A, B, and C receive the same daily dosage of lopinavir/ritonavir (LPV/r), emtricitabine (FTC), and stavudine extended release (d4T XR) or tenofovir DF (TDF). In Arm A, drugs are self-administered for 48 weeks; LPV/r is taken twice daily and FTC and d4T XR or TDF once daily. In Arm B, all drugs are self-administered once daily for 48 weeks. In Arm C, drugs are taken once a day under directly observed therapy during Weeks 0-24, and then by self-administration during Weeks 25-48. Adherence to the regimen is measured using an electronic drug monitoring system. Viral load, CD4 and CD8 T cell responses, population pharmacokinetics, and quality of life indicators are measured throughout the study. The tolerability and safety of the treatment regimens are also monitored.