Non-specific Irreversible platelet cyclooxygenase inhibitor
(COX-1 and 2) via acetylation of serine residues → ↓formation PG precursors.
- Inhibits formation of thromboxane (TXA) → inhibit aggregation
- At higher doses prostacyclin (PFI2) synthesis also inhibited → vasoconstriction (but endothelium can regenerate COX)

Antagonises the GpIIb/IIIa
receptor, preventing the
binding of fibrinogen and
platelet crosslinking and
aggregation.

- PO. BA. 50%.
- 300mg Loading. 100mg maint.

85% protein binding, pKa 3

Vd 10L

- Converted to salicylic acid in GI mucosa and liver
- Hepatic conjugation (saturable)

Limited metabolism in humans.

- Renal as salicylate

Excreted in urine and faeces, mostly
unchanged

- T1/2b 15~20 mins when first order
- Dur: 4-6 hrs. (Effect on platelet aggregation will last life of current cohort of platelets (7-10 days)

HL 1.9-2.2 hrs

Bleeding
Bronchospasm, Renal toxicity
Reye’s Syndrome, GI ulceration
Caution with other anticoagulants

Haemorrhage
Difficulty reversing agent
Dose adjustment in renal impairment

Antiplatelet

Antiplatelet

COX inhibitor

GP IIb/IIIA Inhibitor

Level 1

Level 3

Platelet inhibition

Platelet inhibition