Antidotes for Bleeding Caused by Novel Oral Anticoagulants

Anticoagulation, the thinning of the blood to treat abnormal clotting, is used by physicians to treat existing clots and to prevent new clots. The inherent problem with anticoagulation is that it not only prevents abnormal clotting but also interferes with normal clotting. This was evident with the anticoagulant warfarin (Coumadin), with which, even with carefully monitored anticoagulation, serious bleeding complications sometimes occur.1 Warfarin, also known as a vitamin K antagonist, thins the blood by preventing the body from synthesizing several clotting factors required for normal coagulation. Those clotting factors all require vitamin K for their production.When warfarin-related bleeding complications occur, physicians reverse the warfarin anticoagulation, that is, return “thinned” blood to a more normal clotting condition, by following protocols that are in turn guided by the measured anticoagulation effect that warfarin induces. That measurement is done with a blood test called the international normalized ratio, which is readily available in hospital and outpatient laboratories. The international normalized ratio provides physicians with laboratory information that can help them decide whether to give extra vitamin K or to administer concentrated doses of the clotting factors to treat patients who are bleeding because of the warfarin.Over the past 5 years, 4 new (novel) drugs have come to market that …