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Antiplatelet — COX-1 Inhibitor

Aspirin (Orthopaedic VTE Prophylaxis)

Brand names: Aspirin 75 mg, Aspirin 150 mg

This entry covers low-dose aspirin used as an option for extended venous thromboembolism prophylaxis after major lower-limb orthopaedic surgery; it is an oral antiplatelet agent.

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

Aspirin irreversibly acetylates platelet cyclo-oxygenase-1, blocking thromboxane A2 production and thereby reducing platelet aggregation for the lifetime of the platelet.

Prescribing in practice

  • Gastrointestinal bleeding and irritation are the main risks, so use cautiously with a history of peptic ulcer disease and consider gastroprotection, and avoid in active bleeding or aspirin hypersensitivity.
  • It is typically used as part of a defined prophylaxis pathway, often following an initial period of another agent or alongside mechanical prophylaxis per local protocol.
  • Bleeding risk is additive with anticoagulants, other antiplatelets and NSAIDs.

Monitoring

Monitor for signs of bleeding and gastrointestinal symptoms during the prophylaxis course rather than by laboratory testing.

Counselling the patient

  • Take with or after food and complete the prescribed prophylaxis course to keep the clot risk down after surgery.
  • Report indigestion, black or bloody stools, or unusual bruising or bleeding.

Evidence & guidelines

Trials including PEP and CRISTAL, alongside NICE guidance, support aspirin as one option for VTE prophylaxis after major orthopaedic surgery.

Reference: EPCAT II Trial (NEJM 2018); NICE NG89; AAOS VTE Prevention Guidelines; 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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