Andexanet alfa
Andexxa
Recombinant modified factor Xa decoy — Xa-inhibitor reversal agent
Catalytically inactive factor Xa 'decoy' that binds and sequesters rivaroxaban/apixaban (and, off-label, edoxaban/LMWH/fondaparinux), restoring endogenous Xa activity.
Indications
- •Reversal of apixaban or rivaroxaban for life-threatening/uncontrolled bleeding
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Low dose | 400 mg IV bolus + 4 mg/min × up to 120 min (last DOAC dose <8 h ago / lower dose) | — |
| High dose | 800 mg IV bolus + 8 mg/min × up to 120 min (higher/recent dose) | — |
Pharmacokinetics
Onset immediate; anti-Xa activity rebounds after the infusion ends (bolus + infusion design).
Side effects
- !Thrombotic events (~10% — prothrombotic)
- !Infusion reactions
- !Very high cost
Contraindications
- ×None absolute — weigh thrombotic risk
Clinical pearls
- ★SPECIFIC (relatively) to factor Xa inhibitors; 4-factor PCC (Kcentra) is the common, cheaper alternative.
- ★Anti-Xa activity returns after the infusion — bridge to definitive management.
- ★Notable thrombotic risk — reserve for true life-threatening bleeds.
Other drugs in Coagulation Related
- Heparin (unfractionated)
Activates antithrombin → inactivates IIa (thrombin) and Xa.
- Tranexamic Acid (TXA)
Reversibly binds plasminogen, blocking conversion to plasmin → preserves fibrin clot.
- Protamine Sulfate
Strongly basic (positive-charge) protein binds to highly acidic (negative-charge) heparin → inactive ionic complex → renal excretion. 1 mg protamine neutralizes ~100 units heparin.
- DDAVP (Desmopressin)
Selective V2 agonist (renal water retention + Factor VIII/vWF release from endothelial Weibel-Palade bodies). NO V1 vasopressor activity at therapeutic dose.
- Warfarin
Inhibits vitamin K epoxide reductase (VKORC1) → depletes reduced vitamin K → ↓ synthesis of factors II, VII, IX, X and proteins C/S. Full effect takes days (waits for existing factor decay).
- Enoxaparin
Antithrombin-mediated inhibition, weighted toward factor Xa over IIa (~3.8:1). More predictable than UFH — no routine monitoring.
- Dalteparin
Antithrombin-mediated factor Xa > IIa inhibition. Similar profile to enoxaparin; preferred LMWH in cancer-associated VTE (CLOT trial).
- Tinzaparin
Antithrombin-mediated factor Xa > IIa inhibition; higher mean molecular weight than enoxaparin (anti-Xa:IIa ~1.9:1).
Browse all classes: /reference/drugs
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
