The U.S. Food and Drug Administration (FDA) announced marketing approval for a new genetic lab test that will help physicians determine which patients are more sensitive to warfarin, a commonly used anticoagulant that prevents dangerous blood clots. The brand name of the drug is Coumadin®. It is manufactured by Bristol-Myers Squibb of Princeton, NJ.

The Nanosphere Verigene Warfarin Metabolism Nucleic Acid Test identifies some variants of two genes: CYP2C9, which helps the body metabolize, or break down, warfarin; and VKORC1, which helps regulate the ability of warfarin to prevent blood clots. Prior studies have shown that 1/3 of patients metabolize warfarin differently—they experience an increased bleeding risk and subsequently need lower doses of the drug.

In current therapy for thrombosis, dosage and administration of warfarin are individualized for each patient. Factors that are considered include diet, age and other medications the patient takes. 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. If given too large a dose of warfarin, patients are at risk for life-threatening bleeding. If patients receive too low a dose, they are at risk for life-threatening blood clots.

“Today’s action offers physicians the first FDA cleared genetic test for warfarin sensitivity, which is another step in our commitment to personalized medicine,” said Daniel Schultz, MD, director of the FDA’s Center for Devices and Radiological Health. “With this test, physicians may be able to use genetic information along with other clinical information to treat their patients.”

The Nanosphere Verigene Warfarin Metabolism Nucleic Acid Test should not be used as a stand-alone tool to determine dosing; it should be used with clinical evaluation and other tools. The new test is the product of Nanosphere, Inc., a nanotechnology-based molecular diagnostics company based in Northbrook, IL.

Read the entire FDA release

Source: FDA news release dated September 17, 2007 and FDA’s Center for Drug Evaluation and Research Web site: www.fda.gov/cder