What is fondaparinux?

By William Aird

Fondaparinux is a synthetic analog of pentasaccharide mimicking the site of heparin that binds to antithrombin and enhances the inactivation of factor Xa without interaction with factor II (prothrombin):

  • Achieves steady state antithrombotic activity 3-4 days after administration.
  • Almost completely dependent on kidneys for clearance; contraindicated in patients with severe renal impairment (creatinine clearance 30 mL/minute).
  • Half-life ranges from 17 hours in young patients to 21 hours in older adults, and is further increased in patients with renal insufficiency. 
  • Predictable anticoagulant effect so monitoring of anti-Xa levels not usually necessary but anticoagulant effect can be measured by fondaparinux-specific anti-Xa assays.