Responses of different platelet activation pathways to Aspirin/Clopidogrel administration in healthy volunteers

Objective To investigate the inhibition profiles of aspirin and clopidogrel on COX-1 and P2Y12 receptor,and potential interaction between them. Methods A total of 20 healthy male volunteers were admitted and divided into two groups,clopidogrel group(75 mg/d) or aspirin group(100 mg/d) in consecutive 7 days.Platelet inhibition(%),CEPI-CT/CADP-CT and CD62p were detected and recorded before medicine administration and at the 1st,3rd,5th and 7th day after withdraw. Results Both CEPI-CT and CADP-CT changed significantly(F=27.2,P0.01 and F=25.3,P0.01) after clopidogrel use.CEPI-CT was increased significantly to 300s after aspirin administration(F=36.7,P0.01),but CADP-CT showed no changes(F=2.12,P=0.13).Inhibition rate of COX-1 induced by arachidonic acid(inhibitionAA) was increased to 91.7%±0.9%(F=35.1,P0.01) after aspirin administraion.In clopidogrel group,P2Y12 receptor inhibition rate was increased from 47.8%±3.1% to 81.3%±3.8%(F=24.8,P0.01).CD62p expression was decreased by 50% in both groups(clopidogrel: F=28.7,P0.01;aspirin: F=20.7,P=0.02). Conclusions COX-1 activation may interact with P2Y12 receptor in clinical settings and platelet function testing is useful for dual-therapy.