Fondaparinux differs from unfractionated heparin in its mechanism of anticoagulation. Fondaparinux:

• A Directly inhibits thrombin and factor Xa without requiring antithrombin
• B Inhibits factors II, VII, IX, and X via vitamin K antagonism
• C Binds thrombomodulin, converting thrombin to an anticoagulant that activates protein C
• D Selectively catalyzes antithrombin inhibition of factor Xa only, with no direct or antithrombin-mediated inhibition of thrombin ✓

Explanation

Fondaparinux is a synthetic pentasaccharide corresponding to the minimal antithrombin-binding sequence of heparin; it binds antithrombin with high affinity, catalyzing selective inhibition of factor Xa only. Unlike UFH, it does not inhibit thrombin (requires 18+ saccharide chain to bridge antithrombin and thrombin). Because it does not bind platelet factor 4 (PF4), it does not cause heparin-induced thrombocytopenia (HIT) — a significant advantage. It has no direct anticoagulant activity without antithrombin.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.