What it does
Metabolizes codeine, tramadol, tamoxifen, many antidepressants and antipsychotics. Phenotype ranges from poor to ultrarapid metabolizer.
Why this matters for Black patients
African-ancestry populations carry the *17 variant (intermediate metabolism) at much higher frequencies than European populations. This affects efficacy of codeine, tamoxifen, and several SSRIs.
Common variants
| Variant | Phenotype | African | European |
|---|---|---|---|
| *17 | Intermediate metabolizer | 0.200 | 0.005 |
| *4 | Poor metabolizer | 0.050 | 0.200 |
| *xN | Ultrarapid metabolizer (duplications) | 0.050 | 0.010 |
Medications affected by CYP2D6
No recommendation for metoprolol therapy due to insufficient evidence regarding diminished metoprolol effectiveness clinically Initiate standard dosing Initiate therapy with lowest recommended starting dose. Carefully titrate dose upward to clinical effect or guideline-recommended dose; monitor more closely for bradycardia. Alternatively, consider selecting another beta-blocker. No recommendation
Select alternative drug not predominantly metabolized by CYP2D6. Initiate therapy with recommended starting dose Consider a lower starting dose and slower titration schedule as compared to normal metabolizers. Consider a 50% reduction in recommended starting dose, slower titration schedule, and a 50% lower maintenance dose as compared to normal metabolizers. No recommendation
Use tramadol label recommended age- or weight-specific dosing. If no response and opioid use is warranted, consider non-codeine opioid. Use tramadol label recommended age- or weight-specific dosing. Avoid tramadol use because of possibility of diminished analgesia. If opioid use is warranted, consider a non-codeine opioid. Avoid tramadol use because of potential for toxicity. If opioid use is warranted, consider a non-codeine opioid. No recommendation
No action recommended based on genotype for venlafaxine because of minimal evidence regarding the impact on efficacy or side effects. Initiate therapy with recommended starting dose. Consider a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2D6. 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.