Platelet GPIIb-IIIa blockers.

Regardless of the event that stimulates the aggregation of platelets, the receptor alpha(IIb)beta3--one of a family of adhesion receptors known as integrins--has a key role in the process. The past decade has seen the publication of 10 phase III (randomised) clinical trials of four members of a new class of antiplatelet drugs, the GPIIb-IIIa blockers, targeted at this important receptor. Three (abciximab, eptifibatide, and tirofiban) are licensed for human use. 10 other GbIIb-IIIa blockers are in phase II or III human studies. In all 10 placebo-controlled trials, done in the clinical settings of percutaneous coronary intervention or acute coronary syndrome in patients on aspirin, the endpoints favoured the active drug, with a risk reduction for death or non-fatal myocardial infarction of about 21% overall. With attention to heparin dose the risk of bleeding is not a major concern with these agents. The GPIIb-IIIa blockers are taking the clinician and patient out of the era of aspirin monotherapy when platelet inhibition is required.