The Medical Letter on Drugs and Therapeutics
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1426
Rethinking Warfarin for Atrial Fibrillation
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 Select a term to see related articles  Anticoagulants   apixaban   Atrial fibrillation   Coumadin   Dabigatran   Eliquis   Pradaxa   Rivaroxaban   Warfarin   Xarelto 

Full-page newspaper advertisements and a series of television commercials have urged patients with atrial fibrillation to "rethink warfarin" in favor of Eliquis (apixaban – Bristol-Myers Squibb). Apixaban is the latest of 3 new oral anticoagulants now competing with warfarin (Coumadin, and others) for the oral anticoagulant market.1

NEW ORAL ANTICOAGULANTS VS. WARFARIN — Advantages – Unlike warfarin, the new oral anticoagulants do not require INR monitoring and have no dietary restrictions. Dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban all appear to be at least as effective as warfarin in preventing stroke in patients with nonvalvular atrial fibrillation. In clinical trials,2-4 they each caused less intracranial bleeding than warfarin, and apixaban caused less overall bleeding,5 but the trials were conducted in somewhat different populations and used slightly different definitions of major bleeding.

Disadvantages – The 3 new oral anticoagulants are all shorter acting than warfarin, so missed doses could increase the risk of thrombosis. Both apixaban and dabigatran are taken twice daily. Unlike warfarin, the new oral anticoagulants have no specific antidotes to reverse their therapeutic effect; one study found that use of a prothrombin complex concentrate reversed the anticoagulant effect of rivaroxaban, but not dabigatran.6,7 Monitoring of renal function is recommended for dabigatran and rivaroxaban, and probably would be prudent for apixaban as well. All of the new oral anticoagulants are much more expensive than warfarin.

CONCLUSION — Patients with nonvalvular atrial fibrillation who are taking warfarin and whose INR generally remains within the therapeutic range should probably stay on it. New patients and those who are difficult to maintain in the therapeutic range of INR might benefit from treatment with dabigatran (Pradaxa), rivaroxaban (Xarelto), or apixaban (Eliquis). Of the three, apixaban was the only one shown to cause less overall bleeding than warfarin, but direct comparisons between the new drugs and long-term data on outcomes are lacking.

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