Through a new boxed warning, the FDA is alerting healthcare professionals about a subgroup of patients who cannot effectively metabolize the anti-platelet drug Clopidogrel [Plavix].
These patients, called “poor metabolizers,” have little or no activity of the liver enzyme CYP2C19, which converts Clopidogrel [Plavix] to its active form, so they may not experience the full anti-clotting benefits of the drug.
Practitioners should know that tests are available to identify genetic differences in CYP2C19 function and thus identify poor metabolizers. They should consider using other anti-platelet medication or an alternative dosing strategy for these patients. And although raising the dose of Clopidogrel [Plavix] in poor metabolizers can increase anti-platelet response, an appropriate dose regimen has not been established in a clinical trial.