Clopidogrel (Plavix) and Black patients

Clopidogrel has one of the most clinically significant pharmacogenomic stories in cardiology, with important race implications:

• CYP2C19 loss-of-function alleles (*2 and *3) reduce conversion of clopidogrel to its active metabolite. Carriers have higher rates of stent thrombosis and MI.
• The *2 allele is more common in East Asian ancestry (~30 percent) than in African (~16 percent) or European (~13 percent) ancestry populations. Variant prevalence in self-identified Black patients is intermediate.
• The FDA added a boxed warning in 2010 noting reduced efficacy in CYP2C19 poor metabolizers and recommending genotype testing where available.
• For post-ACS and post-PCI patients, the more potent P2Y12 inhibitors ticagrelor (Brilinta) and prasugrel (Effient) are not CYP2C19-dependent and avoid this problem. TAILOR-PCI (Pereira et al., JAMA 2020;324:761–71, PMID 32840595) showed PGx-guided therapy is feasible and safe.
• Specifically in Black patients, a 2023 analysis from the NIH Pharmacogenomics Research Network (PGRN) collaboration recommends CYP2C19 genotype testing before clopidogrel initiation post-ACS, or empiric substitution with ticagrelor when genotyping is not available.

For lacunar stroke prevention, the SPS3 trial (Benavente et al., NEJM 2012;367:817–25) showed dual antiplatelet therapy (clopidogrel + aspirin) did not reduce recurrent stroke but did increase bleeding — limiting DAPT duration to short courses in this indication.