Although there is currently no approved reversal agent for the anticoagulant drug Xarelto, Janssen Pharmaceuticals, in collaboration with Portola and Bayer, is evaluating the safety of PRT4445, a potential antidote for Factor Xa inhibitors like Xarelto, which prolong the time it takes the blood to clot, sometimes leading to serious or fatal bleeding. The goal of the study is to determine the dose of PRT4445 that will be able to reverse the anticoagulant activity of Xarelto in case of an uncontrolled bleeding or other emergency situations.
Xarelto was approved by the U.S. Food and Drug Administration in 2011 as a potentially safer alternative to Warfarin, as Xarelto does not require regular blood monitoring or frequent doctor follow up. Xarelto was originally prescribed to prevent stroke or blood clots in patients suffering from atrial fibrillation and to reduce the risk of blood clots in patients undergoing knee or hip replacement surgery. Approval was expanded in 2012 to allow the drug to be used as a treatment for deep vein thrombosis or pulmonary embolism, but since that time, the FDA has received reports of dangerous blood clots caused by uncontrollable bleeding associated with use of Xarelto.
Although Xarelto is considered relatively safe, effective, and easy to use for both patients and physicians, there is no antidote, as opposed to the reliable warfarin (Coumadin), whose major bleeding rate is approximately 3 percent per year. Warfarin has been the most widely used in the U.S. for more than 50 years, and vitamin K is used 10 to 25 percent of the time to reverse its anticoagulant effects within four to six hours, although emergency situations require blood products such as plasma, prothrombin complex factor, or recombinant factor Vlla.
According to MedPage Today, approximately six million people in the U.S. are on outpatient anticoagulants, and in 2013 200,000 people, or one in 30, were admitted to the hospital due to bleeding complications, including 65,000 who are taking one of the new oral anticoagulants, which include Pradaxa, Xarelto, and Eliquis.