Background and objectives: A fixed-dose combination (FDC) of aspirin and clopidogrel bisulfate may improve medication adherence. However, the absence of data on the relative antiplatelet efficacy of FDC and separate dual pills (SDP) of aspirin and clopidogrel in real-world patients with stable coronary artery disease is a major factor retarding clinical introduction of such an FDC.
Methods: This was a single-centre, randomized, open-label, parallel-group, non-inferiority trial. Patients who maintained a regimen of separate aspirin and clopidogrel pills for at least 1 year after drug-eluting stent implantation without adverse events were enrolled. Patients were randomly assigned to either the FDC group or the SDP group. Antiplatelet efficacy and tolerability were assessed at baseline and at 4 weeks.
Results: Of the 93 enrolled patients, 83 (FDC group: n = 42; SDP group: n = 41) completed the study. The difference in the changes in P2Y12 percentage inhibition did not exceed the predetermined value for inferiority [mean difference -1.7; 95 % confidence interval (CI) -6.9 to 4.5, p < 0.001 for non-inferiority]. The changes from baseline to 4 weeks in P2Y12 reaction units (PRU) (mean difference 9.7 PRU, p = 0.46), maximal platelet aggregation (mean difference 2.0 %, p = 0.44) and aspirin reaction units (ARU) (mean difference -2.3 ARU, p = 0.88) did not differ significantly between the treatment groups. The tolerability of the FDC formulation was similar to that of SDP therapy (p = 0.68).
Conclusion: In patients with prior percutaneous coronary intervention, the antiplatelet efficacy of the aspirin/clopidogrel FDC was non-inferior to that of SDP and the tolerability of the two regimens was similar after 4 weeks of treatment.