Lamivudine 300 mg QD Versus Continued Lamivudine 150 mg BID with Stavudine and a Protease Inhibitor in Suppressed Patients

Abstract

Purpose: To compare the efficacy (sustained virologic suppression) and safety/tolerability of a switch to lamivudine 300 mg once daily (QD) versus continued lamivudine 150 mg twice daily (BID) in virologically suppressed patients (HIV-1 RNA <400 copies/mL for ≥3 months) on stable (≥6 months) therapy with lamivudine 150 mg BID plus stavudine and either indinavir or nelfinavir. Method: Eighty-nine suppressed patients ≥18 years old with CD4 counts >50 cells/mm³ were enrolled in this phase II, open-label, multicenter, randomized, stratified (by pretrial protease inhibitor [PI]), parallel-group clinical trial. Eighty-one patients received either lamivudine 300 mg QD (n = 39) or 150 mg BID (n = 42) with their pretrial stavudine/PI regimens for 24 weeks. Results: A high rate of virologic suppression was sustained with both regimens throughout the trial. At week 24, intent-to-treat:exposed (missing = failure) analyses showed no statistically significant differences in the percentage of patients with HIV-1 RNA <400 copies/mL (95% [QD] vs. 90% [BID]) or <50 copies/mL (82% [QD] vs. 81% [BID]) or in the median change from baseline in CD4 counts (+42 cells/mm³ [QD] vs. +22 cells/mm³ [BID]). Both regimens were well tolerated. No patient experienced virologic failure, clinical disease progression, or a drug-related serious adverse event during the trial. Self-reported medication adherence was high in both groups. Conclusion: Patients who experience virologic suppression with a regimen of lamivudine 150 mg BID in combination with stavudine/PI can maintain that suppression by continuing their regimen or switching to lamivudine 300 mg QD and continuing the other components. Adverse event profiles were comparable among treatment regimens, and no new safety concerns were raised.