Latebreakers: Warfarin label now to include genetic info

Information on how genetic variations can affect a patient's response to warfarin must now be included on the drug's label, according to the FDA. A recent agency teleconference discussed how use of genetic testing can help determine an appropriate initial dose of the drug and lower the risk for bleeding complications. One-third of patients are thought to metabolize the anticoagulant differently than expected and that is often due to genetic variations in the CYP2C9 and VKORC1 genes. In related news, results of a recent NIH study, published in the Sept. 1 issue of Blood, showed that the combined use of INR and genetic testing has enabled researchers to develop a dosing equation that estimates a therapeutic warfarin dose. The new dosing model can be found on-line at http://www.warfarindosing.org/.