These include idarucizumab, andexanet alpha and PER977. Currently there are a few promising antidotes undergoing clinical trials. Unlike warfarin, there is no antidote for these newer agents. Nevertheless bleeding is still a relevant side effect and their biggest drawback has been the lack of a reliable reversible agent. These drugs are prescribed in fixed doses and have fewer incidents of intracranial hemorrhage in comparison to warfarin in large randomized phase III studies.

They have been approved for prevention of stroke in nonvalvular atrial fibrillation, and recently in prevention of recurrent deep vein thrombosis and pulmonary embolism. Edoxaban has most recently joined the rest. It was soon followed by Factor Xa inhibitors-rivaroxaban and apixaban. In 2010, dabigatran, a direct thrombin inhibitor, became the first target specific anticoagulant approved by FDA. These drawbacks and limitations fuelled the development of newer agents. There were various limitations like its narrow therapeutic index, food and drug interactions, need for regular monitoring and frequent dose adjustments. Warfarin, a vitamin K antagonist (VKA), was the only oral anticoagulant for more than half a century.

Andexanet alfa mechanism of action