Does Genotype Affect a Patient’s Response to Clopidogrel?

Dual antiplatelet therapy with aspirin and clopidogrel is an important secondary preventive measure after treatment of MI or coronary ischemia. Clopidogrel is converted to an effective metabolite by cytochrome P-450 (CYP) enzymes. In two new studies, investigators assessed how patients’ genetic profiles affect platelet inhibition by clopidogrel and plasma concentrations of the active drug metabolite.

In a study sponsored by the manufacturer of a competitor to clopidogrel, investigators examined reduced-function alleles of CYP2C19 (which are present in 30% of whites, 40% of blacks, and 55% of East Asians). After clopidogrel administration, the level of the active metabolite was 32% lower in healthy carriers of at least one reduced-function al…