An antidote to direct inhibitors of coagulation factor Xa specifically blocks the bleeding side-effects of excessive inhibition of factor Xa in animal models, reports a study published online this week in Nature Medicine. This antidote, if shown to work similarly in humans, has the potential to substantially increase the utility of factor Xa inhibitors.
Drugs targeting coagulation factor Xa were recently approved for use in humans to help inhibiting blood clotting and potentially have wide use, replacing warfarin as the standard of care. The antidote, developed by Uma Sinha and her colleagues, is a modified version of recombinant factor Xa. It lacks the normal procoagulation activity of native factor Xa, but still binds to the drugs used to inhibit factor Xa, in effect sopping them up. The authors successfully showed the ability of this antidote to stop bleeding caused by excessive inhibition of factor Xa in rabbits.