Fig 1.

Production of clopidogrel active metabolite and its effect on platelet aggregation. Clopidogrel is metabolized in the liver by cytochrome P450 enzymes, producing Act-Met. Act-Met irreversibly binds and disables the platelet receptor P2Y12. ADP-induced P2Y12 activation causes downstream G-protein signaling, which in turn results in conformational change and activation of the platelet receptor GPIIb/IIIa. This activated GPIIb/IIIa receptor can bind to similarly activated receptors on other platelets via divalent bridging molecules such as VWF and fibrinogen, resulting in platelet aggregation.