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Check with cardiologists before stopping early post stenting.

About : Always Aspirin check the BNF link here
  • Also called Acetylsalicylic acid, a cheap and effective antiplatelet agent and antinflammatory
  • Potent inhibitor of cyclooxygenase (COX) which produce prostaglandins
  • Main medical effect is inhibiting platelet cyclooxygenase
  • Has a pKa of 3.5 and is rapidly absorbed from the stomach
  • Main metabolite is salicylate. Renal excretion increased in alkaline urine
  • Anti inflammatory : effects are based on its inhibition of prostaglandin synthesis
  • Antiplatelet : Irreversibly inhibits Thromboxane synthesis in platelets
  • Analgesic and antipyretic
Mode of action
  • Aspirin acetylates and deactivates cyclooxygenase which makes thromboxane A2
  • This reaction is irreversible and if no further Aspirin is given platelet function is impaired for 10 days until a new population appears
  • Aspirin also blocks endothelial COX activity but this can regenerate and so the predominant effect is on platelets
  • Vascular antithrombotic dose : 75 mg OD, 81 mg OD, 300, 325 mg OD are commonly used doses. Aspirin 300 mg loading dose usually given. Higher doses not necessarily more effective.
  • Ischaemic stroke: Aspirin 300 mg for 14 days then 75 mg.
  • ACS/stent/IHD: Aspirin 75-300 mg OD.
  • Analgesic: Aspirin 300-600 mg PO every 4 hours up to 3 g per day
  • Rheumatic fever : Aspirin 300-600 mg PO every 4 hours up to 3 g per day
  • Rheumatic diseases e.g. ankylosing spondylitis, osteoarthritis, rheumatoid arthritis, and SLE-associated arthritis and pleurisy: : Aspirin 3 g per day in divided doses
Dose range:You must check with BNF or drug datasheet
Aspirin 75/81 mg ODPO
Aspirin300/325 mg OD PO or PR
Aspirin 300-600 mg 4-6 hourlyPO
  • Peptic ulcer, GI bleed, Severe renal or hepatic disease, Known allergy
  • Bleeding disorders e.g. haemophilia
Side effects
  • Gastric erosions, dyspepsia, peptic ulcer disease and upper GI Haemorrhage. Often treated with PPI or H2 blocker in those at increased risk of gastric side effects.
  • Allergic reactions - angioedema, urticaria, Asthma, Renal toxicity
  • Low dose (less than 2 g per day) increases serum uric acid
  • High dose (more than 2 g per day) reduces serum uric acid
  • High doses - tinnitus, vomiting, vertigo "salicylism"
  • Toxicity causes hyperventilation and a respiratory alkalosis and then metabolic acidosis, respiratory depression and cardiac toxicity