Andexanet alfa

Created 25/01/2022, last revision 14/09/2022

until recently, prothrombin complex concentrates (PCCs) were used off-label for the acute life-threatening bleeding secondary to factor Xa (FXa) inhibitors
in 2018, the FDA approved andexanet alfa (ONDEXXYA, ANDEXXA) for the reversal of life-threatening hemorrhages in patients anticoagulated with FXa inhibitors (apixaban/rivaroxaban) → more
- a modified recombinant inactive form of human FXa, which specifically binds to FXa inhibitor molecules and causes their sequestration, thereby rapidly reducing their activity
- positive trials: ANNEXA-A, ANNEXA-R, and ANNEXA-4 [Medscape 2016]
- administered as a bolus over 15-30 minutes, followed by a 2-hour infusion
new guidelines now recommend the use of andexanet alfa as first-line therapy

ANNEXA-4 was a multicenter, prospective, open-label, single-arm trial that evaluated patients with major bleeding
the trial was published in 2019
n = 352
all patients received a bolus of andexanet alfa followed by a 2h infusion to treat major acute bleeding arising after taking a factor Xa inhibitor in the previous 18 h
- ICH 64%, GIT bleeding 26%
- rivaroxaban 36%, apixaban 55%, edoxaban 3%, enoxaparin 6% (only those with dose > 1 mg/kg)
the study evaluated the decrease in anti-Xa activity and hemostatic efficacy after 12h from the end of infusion
- apixaban and rivaroxaban showed a 92% decrease in mean anti-Xa activity; enoxaparin showed a 75% decrease
- hemostasis at 12 h was rated as excellent/good in 82% of patients
mortality/30 days: 14%, thrombotic events: 10%, two patients had a mild reaction after infusion

during and after application, actively monitor for any signs of thromboembolic complications !!
take care of possible rebound phenomenon