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Updated Labeling for Coumadin (Warfarin)

FDA has announced the approval of updated labeling for the widely used blood-thinning drug, Coumadin, manufactured by Bristol-Myers Squibb Co. of Princeton, N.J.

The labeling will explain that people's genetic makeup may influence how they respond to the drug. Manufacturers of warfarin, the generic version of Coumadin, are to add similar information to their products' labeling.

FDA estimates that 2 million people start taking warfarin in the United States every year to prevent blood clots, heart attacks and stroke.

Dosing Challenges

Warfarin is a difficult drug to use because the optimal dose varies and depends on many risk factors, including a patient's diet, age, and other medications they may use.

Patients who take a dose larger than they can tolerate are at risk of life-threatening bleeding. Those who receive too low a dose are at risk of equally dangerous blood clots. Dosing is particularly important at the beginning of therapy, when problems in adjusting the dose can lead to complications such as bleeding.

Warfarin is the second most common drug–after insulin–implicated in emergency room visits for adverse drug events.

Genetic Tests May Help

The labeling change highlights the opportunity for health care providers to use genetic tests to improve their initial estimate of what is a reasonable warfarin dose for individual patients. Testing may help optimize the use of warfarin and lower the risk of bleeding complications from the drug.

These labeling updates are based on an analysis of recent studies that found people respond to the drug differently based, in part, on whether they have variations of certain genes. FDA's personalized medicine initiative makes use of pharmacogenomics--the science that predicts a response to drugs based on a person's genetic make-up.

For More Information

FDA Press Release

New Labeling Information for Warfarin

Date Posted: August 17, 2007

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