The preceding discussion involved antidotes for anticoagulation with warfarin.  There are antidotes in development for all of the NOACs (Figure 26).  A Phase 3 study, RE-VERSE AD,[18] is currently enrolling patients to look at the efficacy of a monoclonal antibody, idarucizumab, to counter bleeding with dabigatran, and there is also currently a Phase 3 study looking at a molecule, andexanet alfa, that will arrest the anticoagulant effect of the factor Xa inhibitors.

The results of a Phase 2 randomized, double-blind study of andexanet alfa were presented recently at the 2013 annual meeting of the American Society of Hematology.