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Anticoagulant — Factor Xa Inhibitor (Indirect)

Fondaparinux (Surgical VTE Prophylaxis)

Brand names: Arixtra

Fondaparinux is a synthetic selective factor Xa inhibitor used for venous thromboembolism prophylaxis after major orthopaedic and other surgery, given by subcutaneous injection.

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 directly inhibiting thrombin.

Prescribing in practice

  • Bleeding is the principal risk and it is renally cleared with a long half-life and no specific reversal agent, so avoid in severe renal impairment and observe strict timing around neuraxial anaesthesia to reduce spinal haematoma risk.
  • The first postoperative dose timing matters because giving it too early increases surgical bleeding.
  • It is contraindicated in active major bleeding and in bacterial endocarditis; use caution in low body weight, where bleeding risk is increased.

Monitoring

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

Counselling the patient

  • Report any unusual bleeding or bruising.
  • Tell the team about any planned spinal or epidural procedure.

Evidence & guidelines

Its use in surgical VTE prophylaxis is supported by NICE NG89 and pivotal orthopaedic surgery trials.

Reference: NICE NG89 (VTE Prophylaxis); PENTATHLON 2000 Trial (NEJM 2001); MHRA SPC Arixtra; ESC VTE Guidelines 2019; 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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