A Food and Drug Administration (FDA) black box warning has been added to the anti-blood clotting medication Plavix (Clopidogrel Bisulfate), alerting patients and health care professionals that some people who take the drug may not be able to effectively metabolize the medication and thus may not receive the full benefits of Plavix. An estimated 2 to 14 percent of the population are poor metabolizers of Plavix.
Plavix is a medication given to reduce the risk of heart attack, unstable angina, stroke, and cardiovascular death in patients with cardiovascular disease. Plavix works by decreasing the activity of blood cells called platelets, making platelets less likely to form blood clots. Patients identified as poor metabolizers of Plavix do not convert the drug to its active form, thus it has less effect on platelets, and therefore less ability to prevent the serious conditions for which it is prescribed.
The boxed warning informs healthcare professionals that tests are available to identify genetic differences in CYP2C19 function. Health care professionals with patients identified as poor metabolizers of Plavix should consider use of other anti-platlet medications or alternative dosing strategies.
Patients are advised not to stop taking Plavix unless told to do so by their healthcare professionals. Those with concerns should discuss their situation with their doctors. Any adverse events associated with this or any other medication should be reported to the FDA MedWatch Adverse Event Reporting program at www.FDA.gov/MedWatch.