January 27, 2009 - The FDA notified healthcare professionals Monday that the makers of Plavix, Bristol-Myers Squibb/Sanofi Pharmaceuticals, agreed to work with FDA to conduct studies to get a better understanding of the effects of genetic factors and other drugs (especially the proton pump inhibitors - PPIs) on the effectiveness of clopidogrel.
FDA is aware of published reports that clopidogrel bisulfate (marketed as Plavix) is less effective in some patients than it is in others. Differences in effectiveness may be due to genetic differences in the way the body metabolizes clopidogrel or that using certain other drugs with clopidogrel can interfere with how the body metabolizes the drug. These studies should lead to a better understanding about how to optimize the use of clopidogrel.
The FDA said it is important to obtaining these data promptly, and the drug manufacturers have agreed to a timeline for completing the studies. The FDA said it will review the new information expeditiously and will communicate its conclusions and any recommendations to the public. The FDA said it may take several months to complete the studies and analyze the results.
Healthcare providers are urged by the FDA to continue prescribing the drug and patients should continue to take clopidogrel as directed. The FDA said clopidogrel has demonstrated benefits in preventing blood clots that could lead to a heart attack or stroke.
However, the FDA said healthcare providers should re-evaluate the need for starting or continuing treatment with a PPI, including Prilosec OTC, in patients taking clopidogrel. Patients taking clopidogrel should also consult with their healthcare provider if they are currently taking or considering taking a PPI.
For more information: www.fda.gov/medwatch/safety/2009/safety09.htm#plavix
November 12, 2025 
