A randomized study of emtricitabine and lamivudine in stably suppressed patients with HIV

Background: Once daily (QD) dosing facilitates regimen simplification and adherence to antiretroviral therapy. Emtricitabine (FTC) QD twice daily lamivudine reverse transcriptase inhibitor compared in this study to newly approved nucleoside (3TC BID). Methods: Controlled, open label equivalence trial of 440 HIV-1-infected patients with plasma HIV-1 RNA stably suppressed on a regimen of 3TC 150 mg BID, stavudine or zidovudine, and a protease inhibitor or non-nucleoside reverse transcriptase inhibitor. Patients were randomized to continue their Current regimen or replace 3TC with FTC 200 mg QD. If HIV-1 RNA levels were less than or equal to pound 400 copies/ml at 48 weeks in Protocol 303, patients could continue on FTC in Protocol 350. The primary analysis was based on virologic failure and response defined by plasma HIV-1 RNA suppression below 400 copies/ml. Results: At baseline, the mean CD4 cell count was 525 (FTC) and 533 x 10(6) cells/l (3TC). At week 48 in Protocol 303, the probability of virologic failure was low, 7% (FTC) and 8% (3TC), and the probability of sustained viral suppression at week 48 was equivalent between treatment arms at both the 50 and 400 copies/ml thresholds. The mean increase in CD4+ T-cell percentage was 2.5% (FTC) and 1.7% (3TC). In Protocol 350, the probability of virologic failure was 11% after 4 years on FTC-containing highly active antiretroviral therapy (HAART). Conclusion: In stably suppressed patients, 200 mg emtricitabine QD was equivalent to 150 mg lamivudine BID. Emtricitabine-containing HAART was associated with a high rate of sustained