Dissecting the activation of thienopyridines by cytochromes P450 using a pharmacodynamic assay in vitro. 2011

Lynn M Abell, and Eddie C-K Liu
Molecular Sciences/Candidate Optimization and Discovery Biology, Bristol-Myers Squibb Company, 311 Pennington-Rocky Hill Road, Pennington, NJ 08534, USA. lynn.abell@bms.com

The thienopyridine antiplatelet drugs, such as ticlopidine, clopidogrel, and prasugrel, require activation by cytochromes P450 in vivo to effectively block platelet aggregation. The study of the metabolic activation of these compounds has been hampered by the lability and reactivity of the ring-opened active metabolite (AM) and by the numerous metabolites that can be formed in such a transformation. We have developed a novel method whereby platelets are incubated with the cytochrome P450 and the thienopyridine of interest for various amounts of time, and the effects on ADP-driven platelet aggregation are directly examined. In this way, the platelet is used as a biosensor for detection of the AM. Using this method, cytochromes P450 capable of converting clopidogrel, prasugrel, and 2-oxo-clopidogrel to metabolites that inhibit ADP-induced platelet aggregation were identified as well as which cytochromes P450 were capable of catalyzing partial reactions (e.g., conversion of 2-oxo-clopidogrel to the AM). These studies show that, in vitro, CYP3A4/5, 2C19, and 2B6 are individually capable of converting clopidogrel and prasugrel to the AM and that the cytochrome P450 preference for these two thienopyridines is very similar.

UI MeSH Term Description Entries
D008861 Microsomes Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) Microsome
D010879 Piperazines Compounds that are derived from PIPERAZINE.
D010974 Platelet Aggregation The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS. Aggregation, Platelet
D010975 Platelet Aggregation Inhibitors Drugs or agents which antagonize or impair any mechanism leading to blood platelet aggregation, whether during the phases of activation and shape change or following the dense-granule release reaction and stimulation of the prostaglandin-thromboxane system. Antiaggregants, Platelet,Antiplatelet Agent,Antiplatelet Agents,Antiplatelet Drug,Blood Platelet Aggregation Inhibitor,Blood Platelet Antagonist,Blood Platelet Antiaggregant,PAR-1 Antagonists,Platelet Aggregation Inhibitor,Platelet Antagonist,Platelet Antagonists,Platelet Antiaggregant,Platelet Antiaggregants,Platelet Inhibitor,Protease-Activated Receptor-1 Antagonists,Antiplatelet Drugs,Blood Platelet Aggregation Inhibitors,Blood Platelet Antagonists,Blood Platelet Antiaggregants,Platelet Inhibitors,Agent, Antiplatelet,Aggregation Inhibitor, Platelet,Antagonist, Blood Platelet,Antagonist, Platelet,Antiaggregant, Blood Platelet,Antiaggregant, Platelet,Drug, Antiplatelet,Inhibitor, Platelet,Inhibitor, Platelet Aggregation,PAR 1 Antagonists,Platelet Antagonist, Blood,Platelet Antiaggregant, Blood,Protease Activated Receptor 1 Antagonists
D001792 Blood Platelets Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation. Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D003577 Cytochrome P-450 Enzyme System A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism. Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000068799 Prasugrel Hydrochloride A piperazine derivative and PLATELET AGGREGATION INHIBITOR that is used to prevent THROMBOSIS in patients with ACUTE CORONARY SYNDROME; UNSTABLE ANGINA and MYOCARDIAL INFARCTION, as well as in those undergoing PERCUTANEOUS CORONARY INTERVENTIONS. CS 747,CS-747,Effient,Efient,LY 640315,LY-640315,LY640315,Prasugrel,Prasugrel HCl,640315, LY,747, CS,CS747,HCl, Prasugrel,Hydrochloride, Prasugrel
D000077144 Clopidogrel A ticlopidine analog and platelet purinergic P2Y receptor antagonist that inhibits adenosine diphosphate-mediated PLATELET AGGREGATION. It is used to prevent THROMBOEMBOLISM in patients with ARTERIAL OCCLUSIVE DISEASES; MYOCARDIAL INFARCTION; STROKE; or ATRIAL FIBRILLATION. Clopidogrel Besilate,Clopidogrel Besylate,Clopidogrel Bisulfate,Clopidogrel Hydrochloride,Clopidogrel Napadisilate,Clopidogrel Sandoz,Clopidogrel, (+)(S)-isomer,Clopidogrel-Mepha,Iscover,PCR 4099,PCR-4099,Plavix,SC 25989C,SC 25990C,SR 25989,Clopidogrel Mepha
D001189 Aryl Hydrocarbon Hydroxylases A large group of cytochrome P-450 (heme-thiolate) monooxygenases that complex with NAD(P)H-FLAVIN OXIDOREDUCTASE in numerous mixed-function oxidations of aromatic compounds. They catalyze hydroxylation of a broad spectrum of substrates and are important in the metabolism of steroids, drugs, and toxins such as PHENOBARBITAL, carcinogens, and insecticides. Microsomal Monooxygenases,Xenobiotic Monooxygenases,Hydroxylases, Aryl Hydrocarbon,Monooxygenases, Microsomal,Monooxygenases, Xenobiotic

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