Fondaparinux Has a Half-Life of Approximately 17 Hours
Fondaparinux is the anticoagulant with a half-life of approximately 17 hours. 1
Pharmacokinetic Profile
Fondaparinux is a synthetic pentasaccharide that selectively inhibits activated factor Xa through antithrombin-mediated mechanisms. 1 The drug exhibits the following key pharmacokinetic characteristics:
- Half-life: Approximately 17 hours, enabling once-daily subcutaneous administration 1
- Bioavailability: 100% after subcutaneous injection with rapid onset of action 2, 3
- Peak plasma levels: Achieved within 2 hours of dosing 4
- Elimination: Excreted unchanged by the kidneys without metabolism 2
Clinical Implications of the 17-Hour Half-Life
Perioperative Management
The relatively long half-life of fondaparinux has important implications for surgical planning:
- Preoperative discontinuation: The last injection should be given more than 36 hours before surgery 1
- Target levels before neuraxial procedures: Aim for levels below the detection threshold (<0.1 mg/mL), which typically requires stopping for more than 48 hours 1
- Postoperative resumption: Can be restarted from the 6th postoperative hour after bleeding risk assessment, with the 17-hour half-life considered when evaluating hemorrhage risk 1
Comparison with Other Anticoagulants Used in HIT
The 17-hour half-life of fondaparinux contrasts significantly with alternative anticoagulants:
- Argatroban: ~50 minutes half-life 1
- Bivalirudin: ~20-30 minutes half-life 1
- Danaparoid: ~24 hours (anti-Xa activity) 1
Dosing Considerations
- Standard dose: 2.5 mg subcutaneously once daily 1
- Renal impairment: Contraindicated if creatinine clearance is <30 mL/min due to renal excretion 1
- No monitoring required: Anti-Xa activity monitoring is not necessary, and fondaparinux does not affect standard coagulation parameters like aPTT or ACT 1
Important Clinical Caveats
When fondaparinux is used alone during PCI, an additional anticoagulant with anti-IIa activity must be administered to prevent catheter thrombosis. 1 The recommended regimen is 85 IU/kg of unfractionated heparin as a loading dose (reduced to 60 IU/kg if a GP IIb/IIIa inhibitor is used concomitantly). 1
In patients with acute heparin-induced thrombocytopenia requiring urgent surgery, the long half-life of fondaparinux may necessitate switching to shorter-acting agents like argatroban or bivalirudin if the thrombotic risk is considered too high. 1
There is no specific antidote for fondaparinux—it is not neutralized by protamine sulfate. 4