What it does
Metabolizes clopidogrel, proton pump inhibitors, several SSRIs, and voriconazole. Variants determine whether drugs are activated or cleared at expected rates.
Why this matters for Black patients
Patients with African ancestry carry CYP2C19*2 and *3 (loss-of-function) alleles at substantially higher rates. For clopidogrel, this means the drug fails to activate and patients remain at high cardiovascular risk.
Common variants
| Variant | Phenotype | African | European |
|---|---|---|---|
| *17 | Rapid metabolizer (gain of function) | 0.180 | 0.210 |
| *2 | Poor metabolizer (loss of function) | 0.150 | 0.130 |
| *3 | Poor metabolizer (loss of function) | 0.010 | 0.001 |
Medications affected by CYP2C19
If considering clopidogrel, use at standard dose (75 mg/day) Avoid standard dose clopidogrel (75 mg) if possible. Use prasugrel or ticagrelor at standard dose if no contraindication. Avoid standard dose (75 mg) clopidogrel if possible. Use prasugrel or ticagrelor at standard dose if no contraindication. Avoid clopidogrel if possible. Use prasugrel or ticagrelor at standard dose if no contraindication. No recommendation Consider an alternative P2Y12 inhibitor at standard dose if clinically indicated and no contraindication. Avoid clopidogrel if possible. Consider an alternative P2Y12 inhibitor at standard dose if clinically indicated and no contraindication.
Consider a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2C19. If citalopram or escitalopram are clinically appropriate, and adequate efficacy is not achieved at standard maintenance dosing, consider titrating to a higher maintenance dose. Initiate therapy with recommended starting dose. If patient does not adequately respond to recommended maintenance dosing, consider titrating to a higher maintenance dose or switching to a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2C19. Initiate therapy with recommended starting dose Initiate therapy with recommended starting dose. Consider a slower titration schedule and lower maintenance dose than normal metabolizers. Consider a clinically appropriate antidepressant not predominantly metabolized by CYP2C19. If citalopram or escitalopram are clinically appropriate, consider a lower starting dose, slower titration schedule and 50% reduction of the standard maintenance dose as compared to normal metabolizers. No recommendation
No recommendation Increase starting daily dose by 100%. Daily dose may be given in divided doses. Monitor for efficacy. Initiate standard starting daily dose. Consider increasing dose by 50-100% for the treatment of H. pylori infection and erosive esophagitis. Daily dose may be given in divided doses. Monitor for efficacy. Initiate standard starting daily dose. For chronic therapy (>12 weeks) and efficacy achieved, consider 50% reduction in daily dose and monitor for continued efficacy.
Increase starting daily dose by 100%. Daily dose may be given in divided doses. Monitor for efficacy. Initiate standard starting daily dose. Consider increasing dose by 50-100% for the treatment of H. pylori infection and erosive esophagitis. Daily dose may be given in divided doses. Monitor for efficacy. Initiate standard starting daily dose. For chronic therapy (>12 weeks) and efficacy achieved, consider 50% reduction in daily dose and monitor for continued efficacy. No recommendation
Initiate therapy with recommended starting dose. Consider a slower titration schedule and lower maintenance dose. Initiate therapy with recommended starting dose. Initiate therapy with recommended starting dose. If patient does not adequately respond to recommended maintenance dosing, consider titrating to a higher maintenance dose or switching to a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2C19 or CYP2B6. Initiate therapy with recommended starting dose Consider a lower starting dose, slower titration schedule and 25% reduction of standard maintenance dose as compared to CYP2B6 normal metabolizers or select a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2B6. Initiate therapy with recommended starting dose. Consider a slower titration schedule and lower maintenance dose than normal metabolizers. Consider a lower starting dose, slower titration schedule and 50% reduction of standard maintenance dose as compared to CYP2B6 normal metabolizers Initiate therapy with recommended starting dose. Consider a slower titration schedule and lower maintenance dose than CYP2C19 normal metabolizers. Consider a lower starting dose, slower titration schedule and 50% reduction of standard maintenance dose as compared to CYP2C19 normal metabolizers or select a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2C19. Select an alternative antidepressant not primarily metabolized by CYP2C19 or CYP2B6. No recommendation Consider a lower starting dose, slower titration schedule and 25% reduction of standard maintenance dose as CYP2B6 normal metabolizers or select a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2B6. Initiate therapy with recommended starting dose. Consider a slower titration schedule and lower maintenance dose than CYP2B6 normal metabolizers.
Note: This page is reference information, not medical advice. Pharmacogenomic differences are about ancestry, not race; race is an imperfect proxy. Discuss any medication changes with your prescriber.