Precision Medicine for Poor Metabolizers of Clopidogrel?

Clopidogrel, an inhibitor of the platelet adenosine diphosphate P2Y12 receptor, is a prodrug that needs to be processed into an active metabolite by the hepatic cytochrome P450 enzyme CYP2C19. Some people are poor metabolizers of clopidogrel, and questions persist about whether these patients should avoid clopidogrel. These researchers conducted a pragmatic, open-label, randomized, clinical trial comparing genotype-guided choice of oral P2Y12 inhibitors to clopidogrel, as part of dual antiplatelet therapy after percutaneous coronary intervention, in people with CYP2C19 loss-of-function variants (TAILOR-PCI trial; NCT01742117).

The sample size was determined based on the assumption that the intervention would reduce the event rate from 6% to …