High clopidogrel loading dose during coronary stenting:: effects on drug response and interindividual variability

Aim To assess platelet inhibitory effects, interindividual variability in platelet inhibition as well as response to a 600 mg, compared to a standard 300 mg, clopidogrel loading dose (LD) after coronary stenting. Methods and results Platelet function profiles were assessed in 50 patients undergoing coronary stenting receiving either a 300 mg (n = 27) or 600 mg clopidogrel LD. ADP (6 muM) and collagen (6 mug/mL) induced platelet aggregation, as well as ADP (2 muM) induced glycoprotein (GP) IIb/IIIa activation and P-selectin expression were assessed at baseline and 4, 24, and 48 h following clopidogrel front-loading. A more intense and rapid inhibition of platelet activation (both GP IIb/IIIa activation and P-selectin expression) were achieved using a 600 mg, compared to a 300 mg, LD throughout the entire 48 hours (p < 0.001). Although there were no differences in platelet aggregation, overall a 600 mg LD increased the number of clopidogrel responders and this was also achieved earlier compared to a 300 mg LD. A 600 mg LD did not reduce interindividual variability of platelet response. Conclusion The use of a 600 mg clopidogrel LD in patients undergoing coronary stenting optimises platelet inhibitory effects early after intervention and may provide a more effective protection against early thrombotic complications. (C) 2004 Published by Elsevier Ltd on behalf of The European Society of Cardiology.