Andexanet Alfa: A Recombinant Modified Human Factor Xa Protein for Drug Reversal of Rivaroxaban and Apixaban

Objective: To review the pharmacology, safety, and efficacy of andexanet alfa (andexanet), a recombinant modified human factor Xa protein for reversal of factor Xa inhibitors. Data Sources: English-language articles were obtained from MEDLINE (1966 to February 2019) using the following key words: andexanet, andexanet alfa, AndexXa, factor Xa, antidote, and reversal. Citations from selected articles were used to identify additional sources. Study Selection and Data Extraction: Available published articles reporting results of human studies of andexanet alfa were reviewed for inclusion. Prescribing information was used to obtain additional information regarding pharmacology, adverse events, contraindications, and precautions. Data Synthesis: Andexanet is a recombinant modified human factor Xa protein indicated for reversal of rivaroxaban and apixaban in patients with life-threatening or uncontrolled bleeding. Onset of action is rapid and sustained throughout bolus and infusion administration. Medication effects subside 1 to 3 hours postadministration. Andexanet is administered as a bolus followed by a 120-minute continuous infusion. Anti-factor Xa activity was reduced by 95% and 92% in apixaban and rivaroxaban groups, respectively, on infusion completion. Thrombin regeneration occurred within 2 to 5 minutes in up to 96% of patients. Minor infusion reactions and gastrointestinal upset were reported most. A black box warning for thrombotic events, cardiac arrest, ischemia, and sudden death should be noted. Conclusions: Andexanet is effective in reversing rivaroxaban and apixaban anticoagulation due to reduction of anti-factor Xa activity in healthy patients and those with acute major bleeds. Safety concerns, including thrombotic risks, exist and should be assessed against individual patient factors.