Table 1. Overview of the different CYP2C19 phenotypes with the coherent CYP2C19 diplotypes and the antiplatelet therapy recommendations when considering clopidogrel for cardiovascular indications.
| Phenotype | CYP2C19 diplotypes |
Response to clopidogrel | Therapeutic recommendation |
|---|---|---|---|
| Ultra-rapid metabolizer (UM) | *17/*17 | Normal or increased antiplatelet response to clopidogrel | If considering clopidogrel, use at standard dose |
| Rapid metabolizer (RM) | *1/*17 | Normal or increased antiplatelet response to clopidogrel | If considering clopidogrel, use at standard dose |
| Extensive metabolizer (EM) | *1/*1 | Normal antiplatelet response to clopidogrel | If considering clopidogrel, use at standard dose |
| Intermediate metabolizer (IM) | *1/*2, *1/*3, *2/*17 or *3/*17 | Reduced antiplatelet response to clopidogrel | Avoid standard-dose clopidogrel. Use prasugrel or ticagrelor at standard dose if no contraindication |
| Poor metabolizer (PM) | *2/*2, *2/*3 or *3/*3 | Significantly reduced antiplatelet response to clopidogrel | Avoid clopidogrel. Use prasugrel or ticagrelor at standard dose if no contraindication |