Aspirin

Question 1

Aspirin - Mechanism of Action

Answer 1

It has antiplatelet, antipyretic, anti-inflammatory and analgesic effects. In prehospital care it’s only administered for its antiplatelet activity.
Aspirin inhibits the enzyme cyclooxygenase which results in the reduction in the formation of prostglandins and thromboxane.
Absorption occurs in the stomach and small intestine.
Metabolised mainly in the liver.

Question 2

Aspirin - Indications

Answer 2

Myocardial Ischaemia.

Question 3

Aspirin - Contraindications

Answer 3

Known severe allergy.

Third trimester of pregnancy.

Question 4

Aspirin - Cautions

Answer 4

Known bleeding disorder.
Clinically significant bleeding.
Known worsening of bronchospasm with NSAIDS.

Question 5

Aspirin - Dosage

Answer 5

300mg

Question 6

Aspirin - Side effects

Answer 6

Increased bleeding.

Question 7

Aspirin - Usual onset of effect

Answer 7

30-60 minutes

Question 8

Aspirin - Duration of effect

Answer 8

3-5 days for anti-platelet activity.

Platelets exposed to aspirin are impaired for life of the platelet which is 7-10 days.

Question 9

Aspirin - Repeats

Answer 9

None.

Question 10

Aspirin - Preparation

Answer 10

300mg dispersable tablets.

Dispersable tablets may be chewed or dissolved in water.

Question 11

Aspirin - Common interactions

Answer 11

Aspirin displaces warfarin from binding sites and increases the activity of warfarin. This effect is most prominent with chronic administration.
Aspirin is indicated if the patient is taking warfarin.