Blood Coagulation
Mechanism of Action
Side Effects
The Future

The Future

Despite its side effects, warfarin is the oral anticoagulant of choice. Alternatives include acenocoumarol (nicoumalone) and phenindione but these are very rarely used. Warfarin (branded or generic) remains the most widely used oral anticoagulant. Its branded version, Coumadin® achieved sales of over $400 million in 1999. For the last 50 years, warfarin has dominated the market of oral anticoagulants.

However, all this may be about to change, with the development of the new drug Exanta® (Ximelagatran) by AstraZeneca. This is the first investigational oral anticoagulant  to reach Phase III trials in more than 50 years, and results from these trials are encouraging. Exanta works by interfering with thrombin, and is thus classified as a Direct Thrombin Inhibitor (DTI). Unlike Coumadin, it can be taken without stringent dietary restrictions or the need for constant laboratory tests to ensure safe levels of medicine are circulating in the bloodstream.It also has fewer interactions with food and other drugs.

Exanta represents a potential medical breakthrough in the prevention and treatment of thromboembolism. It won't hit the market for probably at least 2 years, but when it does, it has the potential of building into a sales blockbuster. Results of much-larger trials in atrial fibrillation are due next spring. If they succeed, AstraZeneca is expected to seek U.S. approval by late 2003 for that indication and some analysts believe it could become a $3 billion-a-year drug. "If Exanta is approved, I think people taking Coumadin (warfarin) will switch to it and that Coumadin will slowly fade away after 60 years on the market," said Dr. Jack Ansell, a researcher from Boston University School of Medicine, in a Reuters interview.

So are we seeing the last days of warfarin? Only the future will tell...