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Anticoagulant — Selective Factor Xa Inhibitor (Synthetic Pentasaccharide)

Fondaparinux (Orthopaedic VTE Prophylaxis)

Brand names: Arixtra

Fondaparinux is a synthetic selective factor Xa inhibitor given subcutaneously for venous thromboembolism prophylaxis after major orthopaedic surgery, including hip fracture, hip and knee replacement.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It binds antithrombin to selectively and indirectly inhibit factor Xa, interrupting the coagulation cascade without direct activity against thrombin.

Prescribing in practice

  • Bleeding risk is increased and it is contraindicated in severe renal impairment because of accumulation; the first post-operative dose timing must respect haemostasis and any neuraxial catheter.
  • Contraindicated in active clinically significant bleeding and bacterial endocarditis.
  • Unlike heparins it does not usually cause heparin-induced thrombocytopenia, but there is no specific reversal agent in routine use.

Monitoring

Monitor renal function and for signs of bleeding; routine coagulation monitoring is not required.

Counselling the patient

  • Given as a once-daily injection under the skin after surgery.
  • Report any unusual or persistent bleeding or bruising.
  • Take care to give it at the recommended time in relation to your operation.

Evidence & guidelines

NICE NG89 lists fondaparinux among pharmacological options for VTE prophylaxis after major orthopaedic surgery.

Reference: PENTATHLON 2000 Trial (NEJM 2001); NICE NG89; SPC Arixtra; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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