Feb 10

Specific dosing recommendations by FDA for Warfarin

The US Food and Drug Administration has updated the labeling for the anticoagulant warfarin with pharmacogenomically guided dosing ranges.


The FDA initially updated the drug's label in 2007 to reflect the influence of the CYP2C9 and VKORC1 genes in metabolizing the drug. Although the agency recommended doctors consider lower initiation doses for patients with variations in these genes, at the time, the FDA held off on making specific dosing recommendations until ongoing outcomes studies were completed

Then on Jan. 22, the FDA updated the "Dosage and Administration" section of the label, following a supplemental new drug application submitted by Bristol-Myers Squibb on July 24, 2009, for Coumadin, the branded version of warfarin.

The drug's label now states: "The patient's CYP2C9 and VKORC1 genotype information, when available, can assist in selection of the starting dose." The label then instructs healthcare providers to refer to a table containing stable maintenance doses observed in multiple patients having different combinations of CYP2C9 and VKORC1 variants. "Consider these ranges in choosing the initial dose," the label recommends.