The FDA announced its approval of Praxabind, a drug designed as an antidote for the anticoagulant effects of Pradaxa.

Praxabind is a response by manufacturer Boehringer Ingelheim Pharmaceuticals to the need for an antidote for the blood thinner Pradaxa to be used in cases of excessive bleeding or where emergency surgery is required.

Praxabind is the first such Pradaxa antidote approved by the FDA. It will be administered via intravenous injection.

The FDA says that in an ongoing open-label trial, Praxabind was administered to 123 patients taking Pradaxa. The anticoagulant effect of Pradaxa was completely reversed in more than 89 percent of these patients within four hours of receiving Praxabind. This open-label trial is ongoing, the agency says.

The FDA also considered the results of three randomized, placebo-controlled trials using 283 healthy volunteer subjects, which showed reduction of plasma concentration of Pradaxa to undetectable levels after administration of Praxabind.

Approval of Praxabind was granted under the FDA’s accelerated approval program. Boehringer Ingelheim will need to continue submitting information after this initial approval. The FDA also says continued approval may be contingent on the results of the ongoing open label trial.

Pradaxa (dabigatran) has been on the market since first earning FDA approval in 2010. It’s approved for the prevention of stroke and systemic embolism in patients with atrial fibrillation and for the treatment and prevention of pulmonary embolism and deep venous thrombosis.

Pradaxa is one of a new generation of anticoagulants that entered the market relatively recently. For decades, the go-to anticoagulant was warfarin, also known by the brand name Coumadin.

Warfarin has its disadvantages, though. Patients on warfarin have to undergo regular blood testing and dosage adjustment to make sure they’re getting just the right amount. They also must regulate their dietary intake of vitamin K, which counteracts the anticoagulant effect of warfarin.

When the new anticoagulants were introduced, their manufacturers touted them as having certain advantages over warfarin in that they did not require regular blood testing or dietary restrictions.

However, the new anticoagulants had at least one significant disadvantage in that at the time they were introduced to the market, there was no reversal agent available that could counteract their anticoagulant effect.

All anticoagulant medications come with the risk of excessive bleeding. For warfarin patients, excessive bleeding can be controlled by administering vitamin K. But before the approval of Praxabind, there was no antidote that could get Pradaxa bleeding under control. A patient suffering from Pradaxa bleeding would simply have to wait for the body to metabolize and eliminate the drug.

The FDA notes that Praxabind is an antidote specifically for Pradaxa, not necessarily for other anticoagulants. Two other new anticoagulants, Xarelto (rivaroxaban) and Eliquis (apixaban), may have their own reversal agent on the way.

Portola Pharmaceuticals, based in San Francisco, is now working on approval for andexanet alfa, which in clinical trials has worked as a reversal agent for Factor Xa inhibitors like Xarelto and Eliquis. Andexanet alfa will not serve as a reversal agent for Pradaxa, which is a direct thrombin inhibitor.