Switching from twice-daily abacavir and lamivudine to the once-daily fixed-dose combination tablet of abacavir and lamivudine improves patient adherence and satisfaction with therapy

Background Patients prefer fewer pills and once-daily (qd) dosing without food restrictions. We assessed the impact on adherence [by Medication Event Monitoring System (MEMS) cap monitoring] of switching from abacavir (ABC) and lamivudine (3TC) twice daily (bid) to ABC/3TC fixed-dose formulation (FDC, Kivexa (R)) qd to achieve a qd regimen. Methods A randomized, open-label, 8-week study comparing adherence, efficacy and safety of immediate vs. delayed switching from ABC/3TC to FDC qd. Results Ninety-four patients were dosed. Significantly improved adherence was observed at week 4 with qd ABC/3TC across all three adherence variables: taking compliance 99.2% (90.7-100%) vs. 96.6% (60.0-100%) (P = 0.017); dosing compliance 97.1% (64.3-100%) vs. 91.9% (33.3-100%) (P = 0.016); and timing compliance 95.5% (53.8-100%) vs. 86.3% (4.3-100%) (P = 0.006). Treatment satisfaction increased significantly at week 4 with ABC/3TC qd [92% (82-99%) vs. 85% (75-93%) (P = 0.004)]. Two patients were withdrawn from the study because of intolerance to ABC/3TC. Conclusions Switching from ABC and 3TC bid to ABC/3TC FDC qd significantly improved adherence by MEMS cap monitoring at week 4 and improved patient satisfaction with therapy. The results remain to be confirmed over a longer follow-up. Use of qd regimens supports adherence and improves treatment satisfaction relative to bid regimens.