“The fact that we don't have an antidote is one of the reasons why some patients don't want to take [novel oral blood thinners] and why some physicians don't want to switch their patients over,” says Stephan Moll, a hematologist at the University of North Carolina School of Medicine in Chapel Hill and medical director of Clot Connect, an educational outreach program about thrombosis. With lawsuits mounting over claims that some of the new blood thinning drugs can cause serious, sometimes fatal, bleeding episodes in patients, reversal agents are badly needed to staunch safety problems.
For anticoagulation, the standard of care—warfarin—may be cumbersome to administer and control, but at least it can be neutralized. Clinicians typically manage unexpected bleeding with vitamin K or with human plasma concentrates such as the prothrombin complex Kcentra from CSL Behring (King of Prussia, Pennsylvania). Neither Pradaxa, a direct thrombin inhibitor, nor the factor Xa inhibitors Eliquis from Pfizer (New York) and Bristol-Myers Squibb (New York), and Xarelto (rivaroxaban) from Bayer/Janssen (Leverkusen, Germany/Titusville, New Jersey), have a suitable drug option to undo their anticlotting effects in the event of emergency surgery or massive, uncontrolled bleeding. (AstraZeneca's platelet aggregation inhibitor Brilinta also suffers the same limitation.)
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