Drug may be less effective in 'poor metabolizers,' leaving them at risk for cardiac events
FRIDAY, March 12 (HealthDay News) -- The U.S. Food and Drug Administration has added a boxed warning to the anti-blood-clotting drug clopidogrel (Plavix) to alert consumers and health care professionals that the drug may be less effective in patients who are unable to metabolize it in order to convert it into its active form.
Clopidogrel does not have its antiplatelet effects until it is metabolized into its active form by the liver enzyme CYP2C19. Therefore, individuals who have decreased functioning of the CYP2C19 liver enzyme may not effectively metabolize the drug, meaning they may not receive the full benefit of treatment and could still be at risk for heart attack, stroke, and cardiovascular death.
The FDA added a warning about this issue to clopidogrel's label in May 2009, but after reviewing more data it decided to highlight the risk in a boxed warning. The agency recommends that health care professionals consider other antiplatelet medications or alternative dosing of clopidogrel in patients who are poor metabolizers.
"We want to highlight this warning to make sure health care professionals use the best information possible to treat their patients," Mary Ross Southworth, of the Division of Cardiovascular and Renal Products in the FDA's Center for Drug Evaluation and Research, said in a March 12 press release.