Jun

14

2022

What is andexanet alfa?

By William Aird

Modified recombinant factor Xa decoy protein that lacks procoagulant activity and binds to direct oral Xa inhibitors, including rivaroxaban and apixaban, low-molecular-weight heparins (LMWHs), and fondaparinux. FDA-approved in 2018 for reversal of rivaroxaban and apixaban when anticoagulation reversal is necessary due to life-threatening or uncontrolled bleeding.

Other information:

  • Immediate onset with duration of activity of about 6 hours.
  • Dosing regimens include:
    • Low-dose regimen – initial IV bolus 400 mg at target rate of 30 mg/minute, followed by infusion at 4 mg/minute up to 120 minutes
    • High-dose regimen – initial IV bolus 800 mg at target rate of 30 mg/minute, followed by infusion at 8 mg/minute up to 120 minutes
  • Most common adverse effects include:
    • Urinary tract infections
    • Pneumonia
    • Infusion-related reactions
Andexanet alfa is a modified recombinant activated human factor Xa (FXa) decoy protein that binds and sequesters FXa inhibitors in their active site with high affinity and a 1:1. Andexanet alfa does not have intrinsic catalytic activity (the amino acid serine in the active site at position 419 is replaced by alanine) and lacks the membrane-binding-carboxyglutamic acid domain (Gla domain) of native FX, responsible for the binding of FXa to phospholipids. Since andexanet alfa is able to reverse only the anti-FXa activity but not the anti-Factor IIa activity of heparin, it is only partial antidote for heparin.

Learn more here.