Clopidogrel, an antiplatelet agent frequently used for secondary stroke prevention, is a prodrug that requires both sufficient intestinal absorption and hepatic modification to produce its active metabolite. An individual's ABCB1 alleles affect clopidogrel absorption, while one's CYP2C19 alleles affect activation of this prodrug. Herein, we explore the role of platelet function assays and genotyping of CYP2C19 and ABCB1 in terms of clopidogrel absorption and activation, and its efficacy in platelet inhibition through three patients who experienced recurrent ischemic stroke despite adherence to clopidogrel. 

Learning Objectives: 

1. Describe the role that platelet function phenotype may play in secondary stroke prevention antiplatelet selection in the future.
2. Describe the role that CYP2C19 and/or ABCB1 genotypes may play in secondary stroke prevention antiplatelet selection in the future.