The federal agency also announced a labeling update for the drug saying such screenings could prevent many complications each year. A research has indicated that the response to the blood-thinning drug depends on a patient's variants of the genes CYP2C9 and VKORC1 that determine how fast warfarin is metabolized.
The doctors can decide the gene variant information to determine the exact dose of warafin. Health Day News quotes Larry Lesko, director of the FDA's office of clinical pharmacology at the Center for Drug Evaluation and Research, as saying, "Patients with these variations may need lower doses of warfarin than patients with the usual forms of these genes." Too high dose can pose risk of life-threatening bleeding while the lower dose can lead to developing blood clots.
FDA says that out of 2 million people start taking warfarin in U.S., about 30 percent of them have these gene variants. The blood thinner is used to prevent blood clots, heart attacks and stroke.
The genetic tests for the gene variants can cost $125 to $500 and it will take time for them to be available in some parts of the United States. According to FDA, Warfarin sends more than 43,000 people to the emergency room each year and is touted as the second most common drug to blame for emergency room visits for adverse drug events, after insulin.
