What it does
Co-metabolizes warfarin, NSAIDs, several oral hypoglycemics.
Why this matters for Black patients
African-ancestry populations carry the *5, *6, *8, and *11 variants (reduced activity) at higher frequencies. Standard warfarin dosing calculators that ignore CYP2C9 variants overdose Black patients.
Common variants
| Variant | Phenotype | African | European |
|---|---|---|---|
| *11 | Decreased function | 0.022 | 0.003 |
| *5 | Decreased function | 0.011 | 0.000 |
| *6 | Loss of function | 0.014 | 0.000 |
| *8 | Decreased function | 0.072 | 0.000 |
Medications affected by CYP2C9
Initiate therapy with recommended starting dose. In accordance with the prescribing information, use the lowest effective dosage for shortest duration consistent with individual patient treatment goals. Initiate therapy with lowest recommended starting dose. Titrate dose upward to clinical effect or maximum recommended dose with caution. In accordance with the prescribing information, use the lowest effective dosage for shortest duration consistent with individual patient treatment goals. Carefully monitor adverse events such as blood pressure and kidney function during course of therapy. Initiate therapy with 25-50% of the lowest recommended starting dose. Titrate dose upward to clinical effect or 25-50% of the maximum recommended dose with caution. In accordance with the prescribing information, use the lowest effective dosage for shortest duration consistent with individual patient treatment goals. Upward dose titration should not occur until after steady state is reached (at least 8 days for celecoxib after first dose in PMs). Carefully monitor adverse events such as blood pressure and kidney function during course of therapy. Alternatively, consider an alternate therapy not metabolized by CYP2C9 or not significantly impacted by CYP2C9 genetic variants in vivo. No recommendation
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.