First Generic Warfarin In USA Targets $500 Million Market

The US Food and Drug Administration has approved the first genericversion of DuPont Merck's anticoagulant Coumadin (warfarin sodium), which has sales of $500 million a year in the USA. Barr Laboratories expects to begin shipping its generic, in seven dose forms, in the summer.

DuPont had tried to prevent the approval by changing equivalence standards for the drug. The company petitioned the FDA to adopt an individual bioequivalence standard for warfarin, rather than the average bioequivalence standard used in the approval process for Barr's product, because warfarin has a very narrow therapeutic index. The FDA allows the rate and extent of absorption of generic products to vary by as much as -20% or +25% of the branded version to be classed as bioequivalent, and DuPont believes these standards should be tighter for drugs like warfarin.

Barr dismisses DuPont's claims. Barr's chief executive, Bruce Downey, said: "the FDA approval affirms the existing USP and FDA bioequivalence requirements for generic versions of Coumadin and ends an attempt by the branded company to use the federal regulatory process to thwart competition."