P2Y(12) inhibitors: differences in properties and mechanisms of action and potential consequences for clinical use

Currently, clopidogrel is recommended for treatment of patients with acute coronary syndrome and/or percutaneous coronary intervention. However, the delayed onset of the effect and the occurrence of poor platelet inhibition responders with clopidogrel as well as non-compliance to dual antiplatelet treatment are associated with a raised risk of stent thrombosis. The molecular target of the active metabolite of clopidogrel and several emerging antiplatelet treatments is the P2Y(12) receptor, which is the main platelet receptor responsible for ADP-induced platelet aggregation. Active metabolites of the thienopyridine prodrugs (ticlopidine, clopidogrel, and prasugrel) covalently bind to the P2Y(12) receptor and are irreversible, indirect platelet inhibitors. The newer, direct-acting P2Y(12) inhibitors (cangrelor and ticagrelor) change the conformation of the P2Y(12) receptor, resulting in reversible, concentration dependent inhibition of the receptor. An understanding of the similarities and differences in the properties and mechanisms of action of these new inhibitors compared with clopidogrel is needed in order to optimize the development and use of these agents in clinical practice. The objectives of this systematic review are to summarize the pharmacokinetics, pharmacodynamics, and pharmacogenetics of the different P2Y(12) inhibitors and to discuss the clinical implications for treatment of patients.