Nat. Rev. Cardiol. doi:10.1038/nrcardio.2015.113 Figure 5 Biological hypothesis for P2Y12-receptor occupancy after administration of a LD of prasugrel, with or without previous exposure to clopidogrel Figure 5| Biological hypothesis for P2Y12-receptor occupancy after administration of a LD of prasugrel, with or without previous exposure to clopidogrel. After administration of a LD of clopidogrel, P2Y12 receptors are only partially occupied by the active metabolite of the drug. Therefore, the administration of a LD of prasugrel to a patient already treated with clopidogrel would lead to blockade of the remaining uninhibited P2Y12 receptors by the active metabolite of prasugrel. When all the receptors have been occupied, the remaining molecules of the active metabolite of prasugrel do not bind to any receptor and are immediately hydrolysed. The extent of P2Y12-receptor occupancy when prasugrel is added to clopidogrel would be similar to that resulting from therapy with prasugrel alone. Abbreviation: LD, loading dose. Rollini, F. et al. (2015) Switching P2Y12-receptor inhibitors in patients with coronary artery disease Nat. Rev. Cardiol. doi:10.1038/nrcardio.2015.113