Factor Xa inhibitor reversal agent Pregnancy: Limited data. Use if life-threatening haemorrhage.

Andexanet Alfa (Ondexxya)

Brand names: Ondexxya

Adult dose

Dose: Low dose: 400 mg IV bolus at 30 mg/min, then 480 mg IV infusion at 4 mg/min over 2 hours; High dose: 800 mg bolus, then 960 mg infusion

Route: IV (bolus then infusion)

Frequency: Single course

Max: High dose (800 mg bolus + 960 mg infusion) for rivaroxaban >10 mg or apixaban >10 mg taken ≤8 hours ago or unknown timing

Reversal of apixaban or rivaroxaban in acute major/life-threatening bleeding. Low dose: apixaban ≤5 mg BD or rivaroxaban ≤10 mg OD taken >8 hours ago. High dose: apixaban >5 mg BD or rivaroxaban >10 mg OD or unknown timing. Not available in all centres — use 4-factor PCC (Beriplex 50 units/kg) as alternative.

Paediatric dose

Route: IV

Frequency: Not established in children

Max: Not established

Not established in children. Contact haematology specialist.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

No dose adjustment required.

Clinical pearls

Only licensed for Factor Xa inhibitor reversal (apixaban, rivaroxaban)
ANNEXA-4 trial: haemostatic efficacy 82%
Expensive and not universally available — 4-factor PCC (50 units/kg) used in most UK centres
Thrombosis risk after reversal: restart anticoagulation as soon as clinically safe
Does not reverse dabigatran — use idarucizumab for dabigatran reversal

Contraindications

Hypersensitivity to andexanet alfa

Side effects

Thromboembolic events (high risk — underlying condition unprotected after reversal)
Infusion-related reactions
Pneumonia

Interactions

No significant drug interactions

Monitoring

Anti-Xa levels
Clinical haemostasis
Thromboembolism

Reference: BNFc; BNF; NICE NG196; ANNEXA-4 trial; Ondexxya SPC. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways