Aspirin (Acetyl Salicylic acid)

Platelet activation is a key step in acute arterial thrombosis. Small doses of aspirin block platelet aggregation by irreversible inhibition of the platelet enzyme cyclooxygenase, preventing formation of thromboxane A2, a pro-aggregatory vasoconstrictor

Indications

Prophylaxis in cases of increased risk of blood clotting. Myocardial infarction, coronary bypass, transluminal angioplasty, strokes, transient ischaemic attack.

Dosage

50-100 mg daily or as required

Contra-Indications

Hypersensitivity, haemophilia, hypoprothrombinaemia, platelet disorders, active peptic ulceration & other bleeding disorders

Special Precautions

May precipitate bronchospasm & induce asthmatic attacks in susceptible subjects. Gastrointestinal haemorrhage. Gout. Pregnancy.

Side Effects

G.I. discomfort, nausea, vomiting

Drug Interactions

PABA may increase serum levels. Urinary alkalisers, antacids, corticosteroids may increase excretion, may potentiate the effects of anticoagulants, hypoglycaemics, methotrexate, tricyclic antidepressants. May antagonise uricosurics, spironolactone and tetracyclines