Andexanet

Andexanet (andexanet alfa) is a recombinant, catalytically inactive form of human factor Xa designed as a decoy to reverse the anticoagulant effects of direct factor Xa inhibitors. It is used as a reversal agent in adults who experience life-threatening or uncontrolled bleeding while receiving factor Xa inhibitors such as rivaroxaban, apixaban, or edoxaban.

Mechanism of action is based on high-affinity binding to factor Xa inhibitors. By sequestering these drugs, andexanet restores activity of endogenous factor Xa and promotes reestablishment of the coagulation cascade, helping to control bleeding.

Administration is by intravenous infusion, typically starting with a bolus followed by a continuous infusion. Dosing depends on the specific Xa inhibitor involved and the last dose taken, and it is administered in a hospital setting with close monitoring. The onset of reversal is rapid, but the duration of effect is limited by the drug’s clearance, and bleeding can recur if the reversal is not maintained or if other coagulopathy is present.

Safety considerations include an increased risk of thrombotic events after reversal, as normal coagulation is restored only temporarily. Other potential adverse effects include infusion-related reactions and transfusion-related complications. Because andexanet can interfere with anti-factor Xa activity assays, laboratory monitoring may be affected after administration.

Limitations include its lack of efficacy against non–Xa anticoagulants such as warfarin or direct thrombin inhibitors. The article’s scope focuses on reversal of anticoagulation in adults treated with factor Xa inhibitors experiencing major bleeding.