The U.S. Food and Drug Administration (FDA) approved updated labeling for Coumadin® on August 16, 2007. The drug is a commonly prescribed anticoagulant therapy for the prevention of clots in at-risk patients. While effective, it is also known to cause dangerous bleeding in some patients. Warfarin is the generic version of the drug.

The FDA approval comes in light of several recent studies that have demonstrated that knowledge of the presence of certain detectable genetic variations in individual patients could help physicians establish optimal dosage for the blood-thinning drug. Until now, doctors have been using a trial-and-error approach to treatment, adjusting warfarin dosage in the early stages of therapy, when the risk for serious bleeding is typically highest.
The new genetic screening tests identify specific variants in the genes CYP2C9 and VKORC1.  Some people metabolize the drug differently, depending on which variant of the gene they possess. For patients given too large a dose of warfarin, life-threatening bleeding could result. For those given too low a dose, blood clots could develop.

“Today’s approved labeling change is one step in our commitment to personalized medicine,” said Andrew C. von Eschenbach, MD, FDA Commissioner. “By using modern science to get the right drug in the right dose for the right patient, FDA will further enhance the safety and effectiveness of the medicines Americans depend on.”

The FDA stated that warfarin manufacturers will also add comparable updates to their labels.

To learn more go to Questions and Answers on New Labeling for Warfarin

Source: FDA news release dated August 16, 2007