Aspirin

Question 1

What drug class is Aspirin?

Answer 1

Cyclo-oxygenase inhibitor

Question 2

What are the common indications for Aspirin?

Answer 2

• AF before anticoagulants
• Secondary prevention of strokes and TIA (300mg daily for 2 weeks initially)
• Secondary prevention of ACS (NSTEMI/STEMI - initial once 300mg chewable)
• Post primary PCI

Question 3

What is the mechanism of action of Aspirin?

Answer 3

Inhibits COX-1 mediation production of thromboxane A2 (TXA2) so reduces platelet aggregation.

Irreversible, lasts 7-10 days before platelets all produce new COX-1 (platelets can’t produce more as no nucleus)

75mg for anti platelet action

Doesn’t completely inhibit platelet aggregation as there are other aggregating agents

There are COX-1 polymorphisms so in some individuals, not very efficient

Question 4

What are the common adverse reactions of Aspirin?

Answer 4

• GI irritation, GI bleeding (peptic ulcer)
• haemorrhage (stroke)
• hypersensitivity

Question 5

What are the common drug-drug interactions of Aspirin?

Answer 5

• Other antiplatelets
• Anticoagulants
  Do they have a synergistic or additive effect? so use with caution