Glycoprotein IIb/IIIa antagonists

• the final common pathway for platelet activation is the aggregation of platelets through fibrinogen bound to glycoprotein IIb-IIIa (GPIIb/IIIa) via the RGD (arginine-glycine-alanine sequence) in the fibrinogen alpha chain
• GPIIb/IIIa receptor antagonists are capable of producing a 'thromboasthenic state' because of the blocking of platelet aggregation - with an associated risk of bleeding. To prevent this, dosing is designed to achieve < 100% receptor occupancy so that some residual platelet function remains
• GPIIb/IIIa antagonists have little effect on platelet degranulation
• abciximab is an example of a GPIIb/IIIa antagonist
• the intravenous use of GPIIb/IIIa antagonists has been shown to be effective in patients undergoing percutaneous coronary intervention (PCI)(1)
  • study evidence also revealed that abciximab reduced the risk of adverse events in patients with non-ST-segment elevation ACS undergoing PCI after pretreatment with 600 mg of clopidogrel. The benefits provided by abciximab appear to be confined to patients presenting with an elevated troponin level (2)
• data from GUSTO-IV has thrown into some doubt the benefit of using abciximab in acute coronary syndromes, without PCI (3)

The summary of product characteristics should be consulted before prescribing a drug of this class.

Reference:

1. Bhatt DL et al.Current role of platelet glycoprotein IIb/IIIa inhibitors in acute coronary syndromes. JAMA 2000;284:1549-58.
2. Kastrati A et al. Abciximab in patients with acute coronary syndromes undergoing percutaneous coronary intervention after clopidogrel pretreatment: the ISAR-REACT 2 randomized trail. JAMA 2006;295:1531-8.
3. GUSTO-IV ACS investigators. Effect of glycoprotein IIb/IIIa receptor blocker abciximab on outcome in patients with acute coronary syndromes without early revascularization; the GUSTO-IV ACS randomised trial. Lancet 2001;357:1915-22