Cardiovascular pharmacology

Aspirin

One of the salicylates, acetylsalicylic acid

Non steroidal anti-inflammatory drug

Pharmacology

Irreversible inhibition of arachidonate cyclo-oxygenase inhibits syntheses of prostaglandins.

Anti-inflammatory activity is related to inhibition of the COX 2 isoenzyme.

Antipyretic effect is due to inhibition of prostaglandins in the hypothalamus.

Analgesic effect is due to lack of prostaglandins in the tissues causing neuronal hyperalgesia.

Benefits of low dose aspirin

Antiplatelet action on COX1 reduces incidence MI and stroke in high risk patients and improves mortality.

Improves patency of coronary graft vessels.

Reduces risk of venous thromboembolism.

Reduces by almost half the risk of colon cancer and probably rectal cancer.

May reduce pregnancy related hypertension and may help in radiation induced diarrhoea.

Unwanted effects

Inhibits prostaglandin activity in the gastric mucosa so causes localised vasoconstriction. This means digestive enzymes and HCl which have `diffused backwards` are not washed away. His may lead to ulceration and haemorrhage.

Dyspepsia, nausea, vomiting, skin reactions

`Analgesic associated nephropathy` after long term high doses of NSAIDs

Reye’s syndrome in children is very rare.

High doses may lead to tinnitus, dizziness, decreased hearing, nausea, vomiting.