Aspirin

Indications

• • Headache

  • Pain

  • Prevention of heart attacks and strokes

  • Coronary and carotid arteries, bypasses and stents

Dosage

• • Acute MI

    • 300 mg sublingually

  • Prophylactic

    • 40-75 mg

Administration/Absorption

• • Oral

Distribution

• • 50–80% of salicylate in the blood is bound by protein

Mechanism

• • Irreversible inactivation of the cyclooxygenase (PTGS - prostaglandin-endoperoxide synthase) enzyme

    • acts as an acetylating agent where an acetyl group is covalently attached to a serine residue in the active site of the PTGS enzyme

  • Irreversibly blocks the formation of thromboxane A₂ in platelets, producing an inhibitory effect on platelet aggregation

    • Activated platelets release the contents of stored granules into the blood plasma, which activate further platelets

    • The granules include ADP, serotonin, platelet-activating factor (PAF), vWF, platelet factor 4, and thromboxane A₂ (TXA₂)

  • 40 mg of aspirin a day is able to inhibit a large proportion of maximum thromboxane A₂ release provoked acutely, with the prostaglandin I2 synthesis being little affected

Excretion

Side effects

• • Reye's syndrome

  • GI bleeds

Interactions

Contraindications