Document Detail


Formation, reactivity, and antiplatelet activity of mixed disulfide conjugates of clopidogrel.
MedLine Citation:
PMID:  23348501     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In this work, we investigated the formation, reactivity, and antiplatelet activity of various mixed disulfide conjugates of clopidogrel. Our results showed that the production of the active metabolite (AM) from 2-oxoclopidogrel by human liver microsomes (HLMs) is greatly affected by the thiol reductants used. Among the 10 thiol compounds tested, glutathione (GSH) is most efficient in producing the AM at a rate of 167 pmoles AM/min/mg HLM. Interestingly, no AM but only the mixed disulfide conjugates were formed in the presence of 6-chloropyridazine-3-thiol (CPT), 2,5-dimethylfuran-3-thiol, and 3-nitropyridine-2-thiol (NPT). The mass spectrometry (MS) and MS(2) spectra of the conjugates of these thiol compounds confirmed the presence of a mixed disulfide bond linkage between the AM and the thiol reductants. Kinetic studies revealed that the mixed disulfide conjugates were capable of exchanging thiols with GSH to release the AM with second order rate constants ranging from 1.2 to 28 M(-1)s(-1). The mixed disulfide conjugates of CPT and NPT showed potent inhibition of platelet aggregation after pretreatment with 1 mM GSH, confirming that the AM is responsible for the antiplatelet activity of clopidogrel. Collectively, our results provide strong support for a cytochrome P450 (P450)-mediated bioactivation mechanism involving the initial formation of a glutathionyl conjugate, followed by thiol-disulfide exchange with another GSH molecule to release the AM. Furthermore, the stable mixed disulfide conjugates identified in this study provide a platform to quantitatively generate the therapeutic AM without the need for P450-mediated bioactivation. This property can be further explored to overcome the interindividual variability in clopidogrel therapy.
Authors:
Haoming Zhang; D Adam Lauver; Benedict R Lucchesi; Paul F Hollenberg
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2013-01-24
Journal Detail:
Title:  Molecular pharmacology     Volume:  83     ISSN:  1521-0111     ISO Abbreviation:  Mol. Pharmacol.     Publication Date:  2013 Apr 
Date Detail:
Created Date:  2013-03-20     Completed Date:  2013-05-14     Revised Date:  2014-04-01    
Medline Journal Info:
Nlm Unique ID:  0035623     Medline TA:  Mol Pharmacol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  848-56     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Blood Platelets / drug effects,  metabolism
Disulfides / chemistry*,  metabolism,  pharmacology*
Male
Platelet Aggregation Inhibitors / chemistry*,  metabolism,  pharmacology*
Rabbits
Ticlopidine / analogs & derivatives*,  chemistry,  metabolism,  pharmacology
Grant Support
ID/Acronym/Agency:
AA020090/AA/NIAAA NIH HHS; CA016954/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/Disulfides; 0/Platelet Aggregation Inhibitors; A74586SNO7/clopidogrel; OM90ZUW7M1/Ticlopidine
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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