Abstract

Emtricitabine, a nucleoside reverse transcriptase inhibitor (RTI), and tenofovir disoproxil fumarate (tenofovir DF), a nucleotide RTI, as a fixed-dose combination tablet (emtricitabine/tenofovir DF) for once-daily oral administration, are used as the nucleoside/nucleotide RTI backbone in combination with other antiretroviral agents, including ritonavir-boosted protease inhibitors (PIs), in the treatment of adults with HIV-1 infection. Emtricitabine and tenofovir DF show good activity against laboratory strains and clinical isolates of HIV-1 in vitro, although strains with resistance to emtricitabine or tenofovir have also been reported. Regimens consisting of once-daily emtricitabine/tenofovir DF 200 mg/300 mg plus lopinavir/ritonavir (in the randomized, double-blind, placebo-matched, multicentre HEAT study) or boosted atazanavir or efavirenz (in the randomized, partially-blind, multicentre ACTG 5202 trial) were effective in the initial treatment of patients with HIV-1 infection (with screening plasma HIV-1 RNA levels of >or=100,000 copies/mL in ACTG 5202). In other randomized studies, emtricitabine/tenofovir DF 200 mg/300 mg once daily was an effective backbone for boosted PI-based regimens in the initial treatment of HIV-1 infection. Treatment-experienced patients with HIV-1 infection also experienced beneficial virological effects when treated with similar regimens. Emtricitabine/tenofovir DF in combination with various boosted PIs was generally well tolerated by adults with HIV-1 infection.