Andexanet Alfa Successfully Reverses Rivaroxaban

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Andexanet alfa, an antidote for the anticoagulant activity of rivaroxaban (Xarelto), met its primary end point during a phase III study of its safety and efficacy, according to an announcement from Portola Pharmaceuticals.

The trial, known as ANNEXA-R, included 41 healthy participants who were treated with 20 mg of rivaroxaban for four days. Each participant was then randomized to an 800 mg intravenous bolus of andexanet alfa or a placebo. The trial results indicated that the drug “immediately and significantly” reversed the steady-state anticoagulation activity of rivoroxaban.

The full results of the study will be presented Monday, March 16, 2015 at the American College of Cardiology 2015 Scientific Sessions in San Diego, Calif.

The ANNEXA-R study is also looking at the safety and efficacy of andexanet alfa administered as an intravenous bolus followed by a continuous infusion of 8 mg/min for 120 minutes; the results are expected in the middle of 2015.

Other companies have shown the andexanet alfa can successfully reverse the anticoagulation activity of apixaban (Eliquis from Bristol-Myers Squibb/Pfizer). Additionally, Daiichi Sankyo is testing andexanet alfa as an antidote to edoxaban (Savaysa).

The FDA has designated andexanet alfa as a breakthrough therapy, a designation given when evidence suggests that the drug represents a substantial improvement over existing therapies on at least one significant end point.

IV drip
Andexanet Alfa Successfully Reverses Rivaroxaban

Portola Pharmaceuticals, the makers of an antidote for rivaroxaban (Xarelto, Bayer Pharma/Janssen Pharmaceuticals), a factor Xa inhibitor that is part of the newest generation of oral anticoagulants, announced today that a phase 3 study testing the safety and efficacy of the antidote met its primary end point.

In the trial, an 800-mg intravenous bolus of andexanet alfa, which was tested in 41 healthy volunteers treated with rivaroxaban 20 mg for 4 days and then subsequently randomized to the study drug or placebo, "immediately and significantly" reversed the steady-state anticoagulation activity of rivaroxaban.

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