After several months of delays, the U.S. Food and Drug Administration has finally approved the first antidote for Factor Xa anticoagulants, also known as “new generation” blood thinners or “Novel Oral Anti-Coagulants” (NOACs).
These medications include rivaroxaban, manufactured and marketed by Bayer and Janssen under the brand name Xarelto, and apixaban, a product of Pfizer and Bristol-Myers Squibb, sold as Eliquis. The companies producing these drugs have claimed they are more effective and have far fewer interactions than warfarin, the standard first-line treatment for blood clotting for the past six decades. The problem is that these medications have done their job too well: by disabling the blood's clotting mechanism, it has caused patients to experience uncontrollable hemorrhaging, even from slight bumps.
AndexXa (andexanet alfa) is a universal antidote, or reversal agent for these medications. The drug has been developed by Portola Pharmaceuticals, a small biotech firm located near San Francisco. AndexXa has been in development since 2014. The company first sought FDA approval in August 2016, but the application was denied over concerns about the manufacturing process. Shortly thereafter, an editorial was published in the New England Journal of Medicine, questioning the safety and efficacy of the antidote. Approval was again delayed this past February when the FDA required additional time to review information from the manufacturer.
Approval was finally granted in May. The first Factor Xa inhibitor to be made available in pharmacies, AndexXa can potentially save thousands of patients taking Xarelto and Eliquis from fatal hemorrhaging. In 2016, there were approximately 22,000 adverse events attributed to Xarelto and other Factor Xa inhibitors. Over 3,000 of those cases were fatal, according to the Institute for Safe Medication Practices (ISMP).
Currently, there are over 20,000 lawsuits pending in federal court against Bayer over injuries attributed to Xarelto. Three of these cases have gone to trial, ending in verdicts for the defendant. In one case, an Indiana plaintiff was awarded nearly $28 million, but the verdict was later overturned. Plaintiffs allege that Janssen Pharmaceuticals and Bayer Health Care failed to conduct adequate research and minimized the risks to patients. One attorney attributes the problem to Xarelto's “narrow therapeutic index.” In simple terms, this means there is very little difference between a safe dosage and one that can be life-threatening, increasing the risk of an overdose.
While AndexXa promises to save patients at risk from taking NOACs, it is not without its own dangers. During clinical trials, 5 percent of subjects wound up suffering from urinary tract infections and pneumonia. Other potential side effects include stroke, heart attack and embolism; the FDA is requiring the package to carry warnings to that effect.