ABSTRACT
Potential procoagulant effects of GP IIb=IIIa blockers are probably the most controversially discussed issues for this class of drugs, especially because clinical trials with oral GP IIb=IIIa blockers revealed disappointing results. The following chapter first reviews structural and
functional data on the integrin receptor aIIbb3. Second, based on the finding that currently clinically used GP IIb=IIIa blockers are ligand mimetics, experimental data is shown, demonstrating an intrinsic activating effect of ligand mimetic GP IIb=IIIa blockers that potentially results in fibrinogen binding to aIIbb3 and in platelet aggregation. At the same time, data are discussed describing nonligand mimetic GP IIb=IIIa blockers as pharmacological alternatives without any intrinsic-activating property. Furthermore, the inhibitory effect of aspirin on GP
IIb=IIIa blocker-induced platelet aggregation is discussed as a clinically relevant finding. And finally, the potential association of GP IIb=IIIa blocker-induced thrombocytopenia with procoagulant effects is described.
