Fondaparinux is a synthetic pentasaccharide with anticoagulant properties. It exerts anticoagulant activity exclusively by:

• A Direct competitive inhibition of thrombin (factor IIa)
• B Inhibiting vitamin K epoxide reductase like warfarin
• C Blocking ADP-mediated platelet P2Y12 receptor activation
• D Selectively catalyzing antithrombin III-mediated inhibition of factor Xa only (not thrombin) ✓

Explanation

Fondaparinux is a synthetic five-sugar sequence that precisely mimics the antithrombin-binding pentasaccharide within heparin. It binds antithrombin III and induces the conformational change necessary to inhibit factor Xa, but unlike heparin it is too short (18 saccharide units needed to bridge antithrombin to thrombin) to catalyze thrombin inhibition. This selective anti-Xa activity confers a predictable dose-response without platelet interaction, eliminating heparin-induced thrombocytopenia (HIT) risk. It requires renal clearance so is contraindicated in severe renal failure.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.