RESUMO
STUDY OBJECTIVE: To evaluate the short-term (12 wks) safety and tolerability of a once-daily, fixed-dose abacavir-lamivudine combination versus twice-daily dosing of the separate components, both with background antiretroviral therapy. DESIGN: Phase IIIB, randomized, open-label, parallel-group, multicenter study. SETTING: One hundred forty-six human immunodeficiency virus (HIV) clinics. PATIENTS: Six hundred eighty antiretroviral therapy-naïve patients with HIV type 1 RNA greater than 1000 copies/ml at baseline. INTERVENTION: Patients were randomly assigned in a 2:1 manner to receive either abacavir 600 mg-lamivudine 300 mg once/day or abacavir 300 mg twice/day and lamivudine 150 mg twice/day. Subjects were stratified based on choice of third or fourth antiretroviral drug (nucleoside reverse transcriptase inhibitor [NRTI], NNRTI, or protease inhibitor), assigned before randomization. MEASUREMENTS AND MAIN RESULTS: The primary end point was occurrence of grades 2-4 adverse events and serious adverse events; abacavir hypersensitivity reactions were considered serious adverse events. Baseline characteristics were similar between the once-daily (455 patients) and twice-daily (225 patients) groups. The rates of all grades 2-4 adverse events were similar: once-daily 33% (150 patients), twice-daily 31% (69). A slightly larger proportion of patients in the twice-daily group experienced drug-related grades 2-4 adverse events: once-daily 10% (47), twice-daily 16% (36). Rates of all serious adverse events (once-daily 11% [49], twice-daily 10% [22]) and drug-related serious adverse events (once-daily 5% [21], twice-daily 8% [17]) were similar. The rate of suspected abacavir hypersensitivity reaction was 5.3% (once-daily 4.4% [20], twice-daily 7.1% [16]), with a higher rate for the NNRTI stratum of the twice-daily group (8.6% [10]) than in any other stratum (once-daily, NNRTI 4.3% [10]; twice-daily, protease inhibitor 5.6% [6]; once-daily, protease inhibitor 4.6% [10]). CONCLUSION: In the short-term, the rates of adverse events in the once-daily and twice-daily groups appeared to be similar. The rate of suspected abacavir hypersensitivity reaction in the once-daily group was lower than the rate in the twice-daily group.