As part of a continued review process, the AndexXa antidote developed to cease potentially-fatal Xarelto bleeding side effects remains unapproved. The Food and Drug Administration (FDA) has initiated a 90-day extension until May 2018, citing the need for more data.

For tens of thousands of patients who have required hospitalization due to Xarelto bleeding, an antidote is greatly needed. But that does not mean the FDA should rush the process.

Xarelto Bleeding Side Effect

Anticoagulants may cause internal bleeding, gastrointestinal bleeding, cranial bleeding, vaginal bleeding, and hemorrhaging. Some blood thinners come with a higher risk, whereas others have an approved antidote.

Johnson & Johnson is the parent company of Janssen, who markets Xarelto alongside Bayer. The new-age blood thinner is classified as a Factor Xa inhibitor, and like Eliquis, there is no antidote to stop Xarelto bleeding.

Initially approved in October 2011, Xarelto is used to reduce the risk of deep vein thrombosis and pulmonary embolism, as well as preventing stroke in patients with non-valvular atrial fibrillation.

An older blood thinner, Warfarin, may also cause major bleeding. Warfarin, also known as Coumadin, has a bleeding side effect that is reversible with vitamin K.

Thousands of Xarelto lawsuits have been filed against the manufacturer, who allegedly improperly marketed the drug as superior to Warfarin, therefore causing more injuries of irreversible bleeding.

AndexXa Antidote Review

Created by biopharmaceutical company Portola Pharmaceuticals, AndexXa (Andexanet alfa) is a pending antidote for the bleeding side effect caused by Xarelto. It is a protein designed to bind to Factor Xa inhibitors, which stop anticoagulating effects and reverses bleeding.

The current study, ANNEXA-4, will be used to confirm if the reversal agent is safe to enter the market. The initial review, as a part of the Biologics License Application (BLA), was scheduled for August 2016, and it had been delayed until February 2018. The approval request will be revisited in May of 2018.

"Portola is developing AndexXa as a universal reversal agent for patients anticoagulated with an oral or injectable Factor Xa inhibitor who experience a serious uncontrolled or life-threatening bleeding event or who require urgent or emergency surgery," according to a news release published by on Portola's website. "The BLA seeks initial approval of AndexXa for reversal of the anticoagulant effects of apixaban and rivaroxaban in patients experiencing uncontrolled or life-threatening bleeding."

The agency expects to conduct a detailed review of the data and make recommendations on labeling and post-marketing safety studies.

In 2015, approximately 80,000 patients in the U.S were hospitalized because of Xarelto bleeding. There are now more than 20,000 Xarelto lawsuits consolidated in a federal multidistrict litigation in the U.S. District Court, Eastern District of Louisiana.

Despite the lack of antidote, manufacturers have requested to expand Xarelto uses to reduce the reducing the risk of major cardiovascular (CV) events. These include CV death, heart attack, or stroke in patients with chronic coronary and/or peripheral artery disease (CAD/PAD). Xarelto may also be approved to reduce the risk of acute limb ischemia in patients with PAD.

While all blood thinners may cause episodes of uncontrollable bleeding, there currently exists no approved antidote to reverse Xarelto bleeding side effects. Hopefully, with safe approval, that will soon change.