Factor Xa Reversal Agent
Andexanet Alfa
Brand names: Ondexxya
Adult dose
Dose: Low dose: 400 mg IV bolus at 30 mg/min, then 480 mg at 4 mg/min for 2 hours. High dose: 800 mg IV bolus at 30 mg/min, then 960 mg at 8 mg/min for 2 hours. Dose depends on anticoagulant (apixaban or rivaroxaban) and last dose timing
Route: Intravenous
Frequency: Single course
Clinical pearls
- Indicated for reversal of apixaban or rivaroxaban in life-threatening or uncontrolled haemorrhage
- NICE TA697 (2021): recommended as an option for reversal in adults with life-threatening haemorrhage
- ANNEXA-4 trial: haemostatic efficacy ~80% in GI bleeding and intracranial haemorrhage
- High-dose regimen: for rivaroxaban >10 mg or apixaban >5 mg taken within 8 hours
- Restart anticoagulation as soon as haemostasis achieved and benefit outweighs risk (typically 24–72 hours for AF; individualise for VTE)
- PCC (prothrombin complex concentrate) remains an alternative where andexanet not available
Contraindications
- No absolute contraindications in life-threatening haemorrhage
- Not recommended for reversal of edoxaban or betrixaban (limited data)
Side effects
- Thromboembolic events (stroke, DVT, PE, MI) — significant risk within 30 days (10–15%)
- Infusion-related reactions (uncommon)
- Hyponatraemia and hypophosphataemia (transient)
Interactions
- Heparin — andexanet transiently inhibits tissue factor pathway inhibitor (TFPI); monitor coagulation
- Anticoagulants started after reversal — reassess and restart as soon as clinically appropriate
Monitoring
- Anti-Xa activity levels (to guide dosing and assess reversal)
- Clinical haemostasis assessment
- Thromboembolic events post-reversal (restart anticoagulation promptly)
- INR (if mixed anticoagulation)
Reference: BNF; NICE TA697 (Andexanet alfa for reversing anticoagulation from apixaban or rivaroxaban, 2021); ANNEXA-4 trial (NEJM 2019); BSH guidance on reversal of anticoagulants; https://bnf.nice.org.uk/drugs/andexanet-alfa/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
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