Aspirin

Question 1

Drug Class of Aspirin

Answer 1

Antiplatelet

Question 2

Presentation of Aspirin

Answer 2

• Tablet (white), 300 mg aspirin

Question 3

Schedule of Aspirin

Answer 3

• S2 (Therapeutic poisons).

Question 4

Pharmacology of Aspirin

Answer 4

Aspirin inhibits platelet aggregation by irreversibly inhibiting 
 cyclo-oxygenase, reducing the synthesis of thromboxane A2 (an inducer of platelet aggregation) for the life of the platelet. This action forms 

the basis of preventing platelets from aggregating to exposed collagen fibres at the site of vascular injury.

Question 5

Metabolism of Aspirin

Answer 5

Aspirin is converted to salicyclic acid in many tissues, but primarily in 
 the GI mucosa and liver. It is subsequently excreted by the kidneys.

Question 6

Indications of Aspirin

Answer 6

• Suspected ACS

* Acute cardiogenic pulmonary oedema

Question 7

Contraindications of Aspirin

Answer 7

• KSAR or hypersensitivity to aspirin or other NSAIDs
• Chest pain associated with psychostimulant 
 overdose[6]
• Bleeding OR clotting disorders (e.g. haemophilia)
• Current GI bleeding or peptic ulcers
• Patients < 18 years

Question 8

Precautions of Aspirin

Answer 8

• Possible aortic aneurysm or any other condition 
 that may require surgery [8]
• Pregnancy
• History of GI bleeding or peptic ulcers
• Concurrent anticoagulant therapy (e.g. warfarin)


Question 9

Side Effects of Aspirin

Answer 9

• Epigastric pain/discomfort
• Nausea and/or vomiting
• Gastritis
• GI bleeding
• NSAID induced bronchospasm

Question 10

Routes of Administration for Aspirin

Answer 10

Per oral (PO)

Question 11

Onset time for Aspirin PO

Answer 11

≈ 10 minutes
 (variable)

Question 12

Duration time for Aspirin

Answer 12

≈ 1 week
 (antiplatelet)

Question 13

Half Life for Aspirin

Answer 13

3.2 hours
 (300–650 mg)

Question 14

Special Notes for Aspirin

Answer 14

• In suspected ACS or acute cardiogenic pulmonary oedema aspirin should be administered following the initial dose of 
 GTN (if indicated).
• Aspirin administration is indicated for patients with suspected ACS or acute cardiogenic pulmonary oedema, even if pain free.
• Patients who have had < 300 mg aspirin in the previous 

24 hours and who present with suspected ACS or acute pulmonary oedema should be administered a dose of aspirin that equates to a total daily dose of 300–450 mg.

Question 15

Adult Dose of Aspirin PO
• Suspected ACS
• Acute cardiogenic pulmonary oedema

Answer 15

≥ 18 years – 300 mg

Chewed and followed by a small
 sip of water (where possible).