US health officials recommend gene test for warfarin users
In the first move of its kind, the US Food and Drug Administration (FDA) has recommended a genetic test prior to the prescription of a blood-thinning drug - warfarin – to help decide on the safest dose that should be given to patients.
The blood-thinning drug warfarin is widely prescribed to patients at risk from blood clots, heart attacks or stroke. Yet it is notoriously difficult to administer (to get the dose right for each individual patient). With the exception of the diabetes drug insulin, warfarin triggers more emergency room visits than any other prescription drug.
Research shows that patients with particular versions of two genes - CYP2C9 and VKORC1 – should be given a lower dose of warfarin. Although patients with these genes can be identified by a simple blood test, ‘more studies are needed to explore the precise starting dose for these patients’, said Dr Larry Lesko, director of the FDA’s clinical pharmacology office.
Under the new guidelines US doctors will not be required to test for the genes, but manufacturers of warfarin prescribed in the US will be required to include information about the genes in the drug’s labelling.
Dr Joe Leigh Simpson, President of the American College of Medical Genetics who are planning to release a position statement on the use of genetic testing for warfarin dosing later this year, believes genetics will play an increasing role in medicine. ‘With 30 million Americans on warfarin and 2 million or more adverse side effects reported annually, the potential for genetic testing to minimize pain and suffering is tremendous’, he said.
Sources:
FDA Approves Updated Warfarin (Coumadin) Prescribing Information
http://www.fda.gov/bbs/topics/NEWS/2007/NEW01684.html
FDA Approves Updated Warfarin (Coumadin) Prescribing Information
http://www.fda.gov/bbs/topics/NEWS/2007/NEW01684.html
For the First Time, FDA Recommends Gene Testing