Andexanet Alfa and Unfractionated Heparin

Q: A 52-year-old male with recent history of pulmonary embolism started on Low Molecular Weight (LMW) heparin two days ago. Patient developed severe gastrointestinal (GI) bleeding. GI service is on way to scope the patient. Patient reports history of vasectomy and refuse to take protamine. Andexanet alfa can be used to reverse anti Factor Xa action of Low Molecular Weight heparin (LMWH)?

A) True

B) False

Answer: A

Andexanet alfa can be used beside protamine to reverse the anti-factor Xa activity of LMW heparin. Andexanet alfa also reverses the anti-factor IIa activity. 

The recommended dose is 800 mg bolus at a rate of 30 mg/min, followed within two minutes by an infusion of 8 mg/minute for up to 120 minutes, with a maximum infusion dose of 960 mg. 

The caveat of using andexanet alfa is the concern for thrombotic events.

#hematology

#toxicity

References:

1. Connolly SJ, Crowther M, Eikelboom JW, et al. Full Study Report of Andexanet Alfa for Bleeding Associated with Factor Xa Inhibitors. N Engl J Med 2019; 380:1326.

2. Lewis J, Iqbal O, Jeske W, Hoppensteadt D, Siddiqui F, Fareed J. Differential Neutralization of Unfractionated Heparin and Enoxaparin by Andexanet Alfa. Clin Appl Thromb Hemost. 2022 Jan-Dec;28:10760296221099934. doi: 10.1177/10760296221099934. PMID: 35535398; PMCID: PMC9096191.

3. Maneno JN, Ness GL. Andexanet Alfa, the Possible Alternative to Protamine for Reversal of Unfractionated Heparin. Ann Pharmacother. 2021 Feb;55(2):261-264. doi: 10.1177/1060028020943160. Epub 2020 Jul 15. PMID: 32667214.