Optimal pretreatment timing for high load dosing (600 mg) of clopidogrel before planned percutaneous coronary intervention for maximal antiplatelet effectiveness

Abstract Background The optimal timing for 600 mg clopidogrel pre-treatment before planned PCI in patients with stable coronary artery disease has never been tested in a randomized trial. Methods The time course of platelet inhibition was investigated in 105 patients pre-treated with clopidogrel ≥6 h before the planned procedure. Flow cytometric analysis of the vasodilator stimulated phosphoprotein (VASP) phosphorylation state was done and a Platelet Reactivity Index (PRI) was calculated prior to treatment (baseline) and at 12, 28, 36, 60, 84 and 108 h after the clopidogrel loading dose administration. Results The maximal inhibition of platelet activation was seen at 28 h post administration (PRI mean 36±23%), and 2/3 of patients had PRI value r S =0.48, p r S =0.77, p Conclusion The time curve of clopidogrel efficacy was dependent on baseline platelet reactivity. Among stable CAD patients, pre-treatment with 600 mg of clopidogrel resulted in maximal antiplatelet efficacy 1 day after drug administration.