The study is designed as a Phase I, non-randomized, open-label, pharmacokinetic study. We hypothesize that administration of tenofovir 150 mg once daily to HIV-infected Thai adults with moderate renal function impairment (CLcr between 30 to <50 mL/min) will provide comparable drug exposure to the current recommended dose of 300 mg every 48 hours.~Confirmed HIV-positive subjects receiving tenofovir (TDF) 300 mg, every 48 hours, as part of an NNRTI-based or lopinavir/ritonavir (LPV/r)-based HAART regimen will be proposed to participate.~Subjects meeting the required criteria will be enrolled into one of 2 groups depending on their HAART regimen: .~Group 1: Subjects receiving tenofovir 300 mg, every 48 hours, in combination with lamivudine and an NNRTI,and a confirmed CLcr 30 to <50 mL/min~Group 2: Subjects receiving tenofovir 300 mg, every 48 hours, in combination with lamivudine and lopinavir/ritonavir, and a confirmed CLcr 30 to <50 mL/min~The study procedures are identical for both groups. All subjects enrolled will have two study visits. At the first visit, a 48-hour pharmacokinetic evaluation will be performed. Immediately following completion of the PK sampling, the tenofovir dose will be changed to 150 mg, once daily. Two weeks later, at the second visit, a 24-hour pharmacokinetic evaluation will be performed. Following completion of the second PK sampling the tenofovir dose will be changed back to 300 mg every 48 hours. At this time the subjects has reach the end of the study.
To assess the drug concentrations of tenofovir (TDF) in HIV-infected Thai adults with moderate renal function impairment when administered at the recommended dose of 300 mg every 48 hours, and at an alternative dose of 150 mg every 24 hours.