Andexanet for Major Hemorrhage in Patients on Factor Xa Inhibitors

An uncontrolled study shows rapid efficacy in reducing elevated anti-FXa inhibitor levels.

The anticoagulant activity of oral direct factor Xa (FXa) inhibitors and low-molecular-weight heparins such as enoxaparin can be reversed by andexanet, a modified, recombinant inactive form of FXa. Andexanet was recently approved by the FDA for this indication in patients on apixaban or rivaroxaban experiencing major bleeding.

To examine the efficacy and safety of andexanet, investigators conducted an industry-sponsored, multicenter, prospective, open-label cohort study in 352 patients with major bleeding while taking an FXa inhibitor. For patients exposed to apixaban, or to rivaroxaban more than 7 hours previously, the bolus dose of andexanet was 400 mg, followed by a 2-hour continuous infusion of 480 mg; for patients exposed to enoxaparin or edoxaban, or to rivaroxaban within 7 hours, the bolus was 800 mg and the infusion dose 960 mg.

The following results were reported:

  • Patients’ mean age was 77 years, bleeding was intracranial in 64% and gastrointestinal in 26%, and most were exposed to apixaban (55%) and rivaroxaban (36%).
  • After the andexanet bolus, anti-FXa activity declined from 150 to 11 ng/mL in those on apixaban, from 212 to 14 ng/mL in those on rivaroxaban, and from 0.48 IU/mL to 0.15 IU/mL in the 16 patients on enoxaparin.
  • Hemostatic efficacy 12 hours after the infusion was rated as excellent or good in 82%.
  • Thrombotic events occurred in 10% during the 30 days after the infusion.
  • No patients developed antibodies to FXa or neutralizing antibodies to andexanet.

COMMENT

In this uncontrolled study, andexanet rapidly decreased elevated levels of anti-FXa inhibitor and improved hemostatic efficacy. Although cessation of bleeding was not directly measured, the decrease in anti-FXa activity predicted the change in extent of intracranial hemorrhage. Although few enoxaparin-treated patients were included in this study, the preliminary data suggest that andexanet could be beneficial for major bleeding related to this commonly used anticoagulant.

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