Clopidogrel and CYP2C19
Clopidogrel is a prodrug: CYP2C19 converts it into the active metabolite that blocks platelets. People with reduced CYP2C19 activity make less of it and have higher rates of stent thrombosis and recurrent heart attack on standard clopidogrel.
Why does CYP2C19 matter for Clopidogrel?
Clopidogrel is a prodrug: CYP2C19 converts it into the active metabolite that blocks platelets. People with reduced CYP2C19 activity make less of it and have higher rates of stent thrombosis and recurrent heart attack on standard clopidogrel. CYP2C19 is a liver enzyme that activates or clears several widely used medicines, including clopidogrel, most proton-pump inhibitors, escitalopram and voriconazole. Two common no-function alleles (*2 and *3) and one increased-function allele (*17) make CYP2C19 activity vary widely between people, and between populations: roughly 2-5% of Europeans but 13-15% of East Asians are poor metabolisers. CPIC publishes prescribing guidance keyed to the resulting phenotype.
What does CPIC recommend for each CYP2C19 phenotype on Clopidogrel?
The guidance below is the CPIC recommendation for prescribers, reproduced for reference. It is written for a clinician who knows the whole picture — never start, stop or change a medicine on the basis of this page.
| Phenotype | CPIC-based guidance |
|---|---|
| Ultrarapid Metabolizer | Standard dose clopidogrel expected to be effective. Normal to increased platelet inhibition. |
| Rapid Metabolizer | Standard dose clopidogrel expected to be effective. |
| Normal Metabolizer | Standard dose clopidogrel expected to be effective. |
| Intermediate Metabolizer | Consider alternative antiplatelet therapy (e.g., prasugrel, ticagrelor) due to reduced clopidogrel activation. |
| Poor Metabolizer | Use alternative antiplatelet therapy (prasugrel or ticagrelor). Clopidogrel is expected to be ineffective. |
Which CYP2C19 alleles decide the phenotype?
The phenotype is read from the two CYP2C19 star alleles a person carries. The full allele table, with the defining variants and their population frequencies, is on the CYP2C19 gene page.
23andMe and AncestryDNA chips genotype the defining variants of *2, *3 and *17 directly (rs4244285, rs4986893, rs12248560), so CYP2C19 is one of the better-covered pharmacogenes on consumer data. Rare alleles are not tested, and a call is only as good as the chip's read at each position.
Other drugs affected by CYP2C19
- Proton Pump Inhibitors (PPIs) — Acid Suppressant
- Escitalopram/Citalopram — SSRI Antidepressant
- Voriconazole — Antifungal
Upload your raw DNA file and see your metaboliser status → · Ask G2: “Does my CYP2C19 genotype affect Clopidogrel?”
Genetic associations describe risk across populations, not a diagnosis for any one person. Most variants shift risk modestly and act alongside lifestyle, environment and other genes. Consumer DNA chips do not read every position and can be wrong at any single one. For general education only; talk to a clinician or genetic counsellor before acting on anything here, and never change a prescribed medicine without your prescriber.