Andexanet Alfa (Ondexxya)

How it works

It is a recombinant modified human factor Xa decoy protein that binds and sequesters factor Xa inhibitors, restoring the activity of endogenous factor Xa and thereby thrombin generation.

Prescribing in practice

• Thromboembolic events have been reported after administration, so resume appropriate anticoagulation as soon as medically advisable once bleeding is controlled.
• It is given as an intravenous bolus followed by a continuous infusion, with the regimen depending on the agent and timing of the last dose, per the SPC.
• It is not indicated for reversal of direct thrombin inhibitors and has limited evidence outside apixaban and rivaroxaban.

Monitoring

Monitor clinically for haemostatic effect and for signs of thrombosis after administration, as anti-factor Xa activity is not a reliable guide to clinical efficacy.

Counselling the patient

• This is an emergency hospital treatment to help stop serious bleeding caused by certain blood thinners.
• Restarting your usual anticoagulant will be considered once the bleeding is controlled to reduce clot risk.
• Report any new chest pain, breathlessness, or limb swelling to the clinical team.

Evidence & guidelines

The ANNEXA-4 study supported haemostatic efficacy of andexanet alfa, and NICE has appraised its use for reversing apixaban or rivaroxaban in life-threatening gastrointestinal bleeding.