Genetic testing can improve the safety of the blood thinner warfarin, a new study reports. Warfarin (Coumadin, Jantoven) is often prescribed to prevent life-threatening blood clots in high-risk patients. However, a patient's genes can influence how warfarin is processed in the body. Too little warfarin will not prevent blood clots while too much can trigger internal bleeding, the researchers explained.
Warfarin is "a widely used anticoagulant, but it causes more major adverse events than any other oral drug. Thousands of patients end up in the emergency department or hospital because of warfarin-induced bleeding. But we continue to prescribe it because it is highly effective, reversible and inexpensive," said study first author Dr. Brian Gage. He is a professor of medicine at Washington University School of Medicine in St. Louis.
The researchers said they found that by looking for variants in three genes, it's possible to make warfarin therapy safer. Variants in one gene affect vitamin K recycling (vitamin K is needed for blood clotting). Variants in another gene affect warfarin sensitivity. And variants in the third gene affect warfarin metabolism in the liver and can cause an overdose if the dose is not adjusted quickly enough, the researchers said.