Dabigatran etexilate is a direct oral anticoagulant (DOAC). What differentiates dabigatran's reversal agent idarucizumab from the reversal agent andexanet alfa used for factor Xa inhibitors?

• A Both are vitamin K analogues that replenish clotting factor synthesis
• B Idarucizumab is a humanised monoclonal antibody fragment (Fab) that binds dabigatran directly, while andexanet alfa is a recombinant modified factor Xa decoy ✓
• C Idarucizumab is a prodrug requiring hepatic activation, while andexanet alfa is given as a loading dose only
• D Both work by enhancing antithrombin III activity to neutralise circulating anticoagulant

Explanation

Idarucizumab (Praxbind) is a humanised monoclonal antibody Fab fragment that binds dabigatran (a direct thrombin inhibitor) with 350 times the affinity of thrombin, rapidly sequestering it and restoring thrombin activity. Andexanet alfa (Ondexxya) is a recombinant modified (catalytically inactive) factor Xa decoy that competitively sequesters factor Xa inhibitors (rivaroxaban, apixaban) by acting as a high-affinity trap. Neither works through antithrombin III or vitamin K mechanisms.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.