Portola Pharmaceuticals recently announced that the U.S. Food and Drug Administration rejected its application for approval or a new antidote for Xarelto and similar blood thinners. Patients taking these blood thinners are at risk of excessive bleeding, which can be fatal, and there is currently no approved antidote to reverse the bleeding.

Xarelto and Bleeding

Xarelto is a blood thinner made by Bayer. It is used to prevent the formation of blood clots, which can cause heart attacks and strokes that can be fatal. Xarelto is a newer blood thinner that prevents blood coagulation in a different way than older stand-by blood thinners like warfarin or heparin. Drugs like Xarelto were designed to be easier to use than these older drugs, and more effective.

The only problem with drugs like Xarelto is that, unlike warfarin, they do not have antidotes. Patients on blood thinners are at risk for excessive bleeding, which can quickly become fatal. Warfarin has an antidote that reverses the drug’s action to stop excessive bleeding. So far Xarelto does not have such a life-saving antidote.

Bayer and Johnson & Johnson, the company that markets Xarelto in the U.S., have come under fire for not adequately warning patients of the risks of the drug. They have faced lawsuits over deaths from excessive bleeding, and plaintiffs in these cases have stated that the companies have made false claims that Xarelto is more effective than warfarin.

Antidote Rejected

Recently the pharmaceutical company Portola has been working to develop and test an antidote for Xarelto. This new drug is called AndexXa, which refers to its action on Factor Xa, a substance that is inhibited by Xarelto to prevent coagulation. This new antidote is supposed to reverse that action and stop bleeding in situations that have become life-threatening.

Portola recently submitted a Biological License Application to get AndexXa approved for use and received a Complete Response Letter (CRL) from the FDA. The CRL informed Portola that approval was denied. The FDA requested more information about how AndexXa would be manufactured. The FDA also wanted a better explanation as to how AndexXa could be used to reverse bleeding caused by two other blood thinners, edoxaban and enoxaparin.

Antidote Desperately Needed

Many patients rely on blood thinners to prevent clots. These include patients in recovery from certain types of surgery who are at special risk of forming clots, as well as patients with atrial fibrillation, a type of heart arrhythmia. These people are at a greater risk of forming a blood clot that could be deadly or cause permanent damage.

Both the FDA and Portola claim to be committed to getting AndexXa approved for use. It could be critical in saving the lives of patients who have little choice but to take a blood thinner, but then face the risk of dying from excessive bleeding.

Xarelto Lawsuits

That there is no antidote to reverse bleeding caused by Xarelto is a major issue that has cost some patients their lives and that has led to a number of lawsuits against Bayer and Johnson & Johnson. Xarelto lawsuits continue to grow as more patients realize that the companies probably did not give them adequate warnings. The original label for the drug did not include information about the lack of an antidote in the warning section, a crucial piece of information that was left out.

Makers of other, similar blood thinners with no antidote, like Pradaxa, have already paid out millions of dollars in settlements to patients and their loved ones. Such settlements may not be far off for Xarelto and its makers. The approval of AndexXa is important, but it may come too late for many patients.