The Experts below are selected from a list of 1254 Experts worldwide ranked by ideXlab platform
Albert Schomig - One of the best experts on this subject based on the ideXlab platform.
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cytochrome p450 2c19 loss of function polymorphism and stent thrombosis following percutaneous coronary intervention
European Heart Journal, 2008Co-Authors: Dirk Sibbing, Julia Stegherr, Wolfgang Latz, Werner Koch, Julinda Mehilli, Katharina Dorrler, Tanja Morath, Albert Schomig, Adnan Kastrati, Nicolas Von BeckerathAbstract:Aims Several studies have demonstrated that the mutant *2 allele of the CYP2C19 681G>A loss-of-function polymorphism is associated with diminished metabolization of clopidogrel into its active Thiol Metabolite and an attenuated platelet response to clopidogrel treatment. It is not known whether patients carrying the mutant CYP2C19*2 allele have a higher risk of stent thrombosis (ST) compared with homozygous CYP2C19*1 wild-type allele carriers following percutaneous coronary intervention (PCI). The aim of this study was to assess the impact of the CYP2C19 681G>A loss-of-function polymorphism on ST following PCI performed after pre-treatment with clopidogrel. Methods and results The study population included 2485 consecutive patients undergoing coronary stent placement after pre-treatment with 600 mg of clopidogrel. Genotypes were determined with a TaqMan assay. The primary endpoint of the study was the incidence of definite ST within 30 days following PCI. Of the patients studied, 1805 (73%) were CYP2C19 wild-type homozygotes (\*1/\*1) and 680 (27%) carried at least one *2 allele (\*1/\*2 or \*2/\*2). The cumulative 30-day incidence of ST was significantly higher in CYP2C19*2 allele carriers (\*1/\*2 or \*2/\*2) vs. CYP2C19 wild-type homozygotes (\*1/\*1) [10 patients (1.5%) in CYP2C19*2 allele carriers vs. 7 (0.4%) in CYP2C19 wild-type homozygotes (\*1/\*1), HR 3.81, 95% CI 1.45–10.02, P = 0.007; P = 0.006 after adjustment for confounding variables]. The risk of ST was highest (2.1%) in patients with the CYP2C19 \*2/\*2 genotype ( P = 0.002). Conclusion CYP2C19*2 carrier status is significantly associated with an increased risk of ST following coronary stent placement.
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absorption metabolization and antiplatelet effects of 300 600 and 900 mg loading doses of clopidogrel results of the isar choice intracoronary stenting and antithrombotic regimen choose between 3 high oral doses for immediate clopidogrel effect trial
Circulation, 2005Co-Authors: Nicolas Von Beckerath, Adnan Kastrati, Dirk Taubert, Gisela Pogatsamurray, Edgar Schomig, Albert SchomigAbstract:Background— For patients undergoing percutaneous coronary intervention, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is currently recommended. It is unknown, though, whether loading doses higher than 600 mg exert additional suppression of platelet function. Methods and Results— Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active Thiol Metabolite, unchanged clopidogrel, and the inactive carboxyl Metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active Metabolite, clopidogrel, and the carboxyl Metabolite compared with loading with 300 mg ...
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absorption metabolization and antiplatelet effects of 300 600 and 900 mg loading doses of clopidogrel results of the isar choice intracoronary stenting and antithrombotic regimen choose between 3 high oral doses for immediate clopidogrel effect trial
Circulation, 2005Co-Authors: Nicolas Von Beckerath, Adnan Kastrati, Dirk Taubert, Gisela Pogatsamurray, Edgar Schomig, Albert SchomigAbstract:BACKGROUND: For patients undergoing percutaneous coronary intervention, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is currently recommended. It is unknown, though, whether loading doses higher than 600 mg exert additional suppression of platelet function. METHODS AND RESULTS: Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active Thiol Metabolite, unchanged clopidogrel, and the inactive carboxyl Metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active Metabolite, clopidogrel, and the carboxyl Metabolite compared with loading with 300 mg (P or =0.38) and no further suppression of adenosine diphosphate-induced (5 and 20 micromol/L) platelet aggregation 4 hours after drug administration was achieved when compared with administration of 600 mg (P=0.59 and 0.39). CONCLUSIONS: Single doses of clopidogrel higher than 600 mg are not associated with an additional significant suppression of platelet function because of limited clopidogrel absorption.
Daniel Mansuy - One of the best experts on this subject based on the ideXlab platform.
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Cytochromes P450 Catalyze Both Steps of the Major Pathway of Clopidogrel Bioactivation, whereas Paraoxonase Catalyzes the Formation of a Minor Thiol Metabolite Isomer
2016Co-Authors: Patrick M Dansette, Gildas Bertho, Julien Rosi, Daniel MansuyAbstract:The mechanism generally admitted for the bioactivation of the antithrombotic prodrug, clopidogrel, is its two-step enzymatic conversion into a biologically active Thiol Metabolite. The first step is a classical cytochrome P450 (P450)-dependent monooxygenation of its thiophene ring leading to 2-oxo-clopidogrel, a Thiolactone Metabolite. The second step was described as a P450-dependent oxidative opening of the Thiolactone ring of 2-oxo-clopidogrel, with intermediate formation of a reactive sulfenic acid Metabolite that is eventually reduced to the corresponding Thiol 4b. A very recent paper published in Nat. Med. (Bouman et al., (2011) 17, 110) reported that the second step of clopidogrel bioactivation was not catalyzed by P450 enzymes but by paraoxonase-1(PON-1) and that PON-1 was a major determinant of clopidogrel efficacy. The results described in the present article show that there are two metabolic pathways for the opening of the Thiolactone ring of 2-oxo-clopidogrel. The major one, that was previously described, results from a P450-dependent redox bioactivation of 2-oxo-clopidogrel and leads to 4b cis, two previously reported Thiol diastereomers bearing an exocyclic double bond. The second, minor one, results from a hydrolysis of 2-oxo-clopidogrel, which seems to be dependent on PON-1, and leads to an isomer of 4b cis, 4b "endo", in which the double bond has migrated from an exocyclic to an endocyclic position in the piperidine ring. These results were obtained from a detailed study of the metabolism of 2-oxo-clopidogrel by human liver microsomes and human sera and analysis by HPLC-MS under conditions allowing a complete separation of the Thiol Metabolite isomers, either as such or after derivatization with 3′-methoxy phenacyl bromide or N-ethyl maleimide (NEM). These results also show that the major bioactive Thiol isomer found in the plasma of clopidogrel-treated patients derives from 2-oxo-clopidogrel by the P450-dependent pathway. Finally, chemical experiments on 2-oxo-clopidogrel showed that this Thiolactone is in equilibrium with its tautomer having a double bond inside the piperidine ring and that nucleophiles such as CH3O– preferentially react on the thioester function of this tautomer. This allowed us to understand why 4b cis has to be formed via an oxidative opening of 2-oxo-clopidogrel Thiolactone, whereas a hydrolytic opening of this Thiolactone ring leads to the "endo" Thiol isomer 4b "endo"
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bioactivation of clopidogrel and prasugrel factors determining the stereochemistry of the Thiol Metabolite double bond
Chemical Research in Toxicology, 2015Co-Authors: Patrick M Dansette, Dan Levent, Assia Hessani, Daniel MansuyAbstract:The antithrombotics of the tetrahydrothienopyridine series, clopidogrel and prasugrel, are prodrugs that must be metabolized in two steps to become pharmacologically active. The first step is the formation of a Thiolactone Metabolite. The second step is a further oxidation with the formation of a Thiolactone sulfoxide whose hydrolytic opening leads to a sulfenic acid that is eventually reduced into the corresponding active cis Thiol. Very few data were available on the formation of the isomer of the active cis Thiol having a trans configuration of the double bond, the most striking result in that regard being that both cis and trans Thiols were formed upon the metabolism of clopidogrel by human liver microsomes in the presence of glutathione (GSH), whereas only the cis Thiol was detected in the sera of patients treated with this drug. This article shows that trans Thiols are also formed upon the microsomal metabolism of prasugrel or its Thiolactone Metabolite in the presence of GSH and that Metabolites ha...
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Thiolactone Sulfoxides as New Reactive Metabolites Acting as Bis-Electrophiles: Implication in Clopidogrel and Prasugrel Bioactivation
2013Co-Authors: Patrick M Dansette, Gildas Bertho, Dan Levent, Assia Hessani, Daniel MansuyAbstract:The antithrombotics of the tetrahydrothienopyridine series, clopidogrel and prasugrel, are prodrugs that must be metabolized in two steps to become pharmacologically active. The first step is the formation of a Thiolactone Metabolite. The second step is a cytochrome P450 (P450)-dependent oxidation of this Thiolactone resulting in the formation of a sulfenic acid that is eventually reduced into the corresponding active Thiol. It has been postulated that the sulfenic acid Metabolite resulted from a nucleophilic attack of water on a highly reactive Thiolactone sulfoxide derived from P450-dependent oxidation of the Thiolactone primary Metabolite. The data described in the present article are in complete agreement with this proposition as they show that it was possible to trap these Thiolactone sulfoxides by a series of nucleophiles such as amines, Thiols, or cyclopentane-1,3-dione (CPDH), an equivalent of dimedone that is used as a sulfenic acid trapping agent. HPLC-MS studies showed that various bis-adducts having incorporated two nucleophile molecules were formed in these reactions. One of them that resulted from the oxidation of 2-oxo-prasugrel by human liver microsomes in the presence of ethanolamine and CPDH was isolated and completely characterized by 1H and 13C NMR spectroscopy in addition to MS and MS2 spectrometry. All Metabolites derived from an attack of H2O or an amine at the CO carbon of the intermediate Thiolactone sulfoxide existed as a mixture of two diastereomers having a cis configuration of the double bond, whereas those formed in the presence of Thiols appeared as a mixture of four diastereomers with a cis or trans configuration of the double bond. This led us to propose tentative mechanisms for the previously reported formation of trans isomers of the active Thiol Metabolite of clopidogrel upon microsomal metabolism of this antithrombotic in the presence of Thiols. The results described in this article showed that Thiolactone sulfoxides are formed as reactive Metabolites during the metabolism of clopidogrel and prasugrel and are able to react as bis-electrophiles with a variety of nucleophiles. The possible implications of the formation of these reactive Metabolites in the pharmacological and/or secondary toxic effects of these drugs remain to be studied
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cytochromes p450 catalyze both steps of the major pathway of clopidogrel bioactivation whereas paraoxonase catalyzes the formation of a minor Thiol Metabolite isomer
Chemical Research in Toxicology, 2012Co-Authors: Patrick M Dansette, Gildas Bertho, Julien Rosi, Daniel MansuyAbstract:The mechanism generally admitted for the bioactivation of the antithrombotic prodrug, clopidogrel, is its two-step enzymatic conversion into a biologically active Thiol Metabolite. The first step is a classical cytochrome P450 (P450)-dependent monooxygenation of its thiophene ring leading to 2-oxo-clopidogrel, a Thiolactone Metabolite. The second step was described as a P450-dependent oxidative opening of the Thiolactone ring of 2-oxo-clopidogrel, with intermediate formation of a reactive sulfenic acid Metabolite that is eventually reduced to the corresponding Thiol 4b. A very recent paper published in Nat. Med. (Bouman et al., (2011) 17, 110) reported that the second step of clopidogrel bioactivation was not catalyzed by P450 enzymes but by paraoxonase-1(PON-1) and that PON-1 was a major determinant of clopidogrel efficacy. The results described in the present article show that there are two metabolic pathways for the opening of the Thiolactone ring of 2-oxo-clopidogrel. The major one, that was previousl...
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metabolic oxidative cleavage of thioesters evidence for the formation of sulfenic acid intermediates in the bioactivation of the antithrombotic prodrugs ticlopidine and clopidogrel
Chemical Research in Toxicology, 2009Co-Authors: Patrick M Dansette, Julie Libraire, Gildas Bertho, Daniel MansuyAbstract:Metabolic cleavage of the CO-S bond of some thioesters RCOSR' with the formation of RCOOH requires a monooxygenase-dependent oxidative activation of this bond. The nature of the S-containing product(s) resulting from this cleavage remains unclear in most cases. This communication provides the first evidence for the formation of sulfenic acid intermediates 4a and 4b during the oxidative cleavage of the CO-S bond of Thiolactone Metabolites 2a and 2b of antithrombotic prodrugs, ticlopidine and clopidogrel, by rat and human liver microsomes. These intermediates have been trapped by dimedone, and the corresponding adducts 5a and 5b have been characterized by mass spectrometry (MS) and (1)H and (13)C NMR spectroscopy. Their formation is monooxygenase-dependent and almost completely inhibited by microsomal cytochrome P450 inhibitors. Moreover, they were also formed upon incubation with microsomes containing recombinant human P450 3A4, 3A5, 2C8, 2C9, 2C19, 2D6, or 1A2. In the presence of Thiols such as mercaptoethanol, N-acetylcysteine, or glutathione, microsomal incubations of 2a led to mixed disulfides that have been characterized by MS and should result from reaction of 4a with these Thiols. At high Thiol concentrations, one observed in HPLC-MS the formation of a product exhibiting the MS expected for the previously described Thiol Metabolite 3a, a reduction product of 4a that has been reported as the pharmacologically active Metabolite of ticlopidine. These data provide the first evidence for the formation of sulfenic acid reactive Metabolites upon P450-catalyzed oxidative cleavage of thioesters. They also provide a first detailed mechanism for the previously described formation of pharmacologically active Thiols such as 3a upon oxidative metabolism of ticlopidine and clopidogrel.
Adnan Kastrati - One of the best experts on this subject based on the ideXlab platform.
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cytochrome p450 2c19 loss of function polymorphism and stent thrombosis following percutaneous coronary intervention
European Heart Journal, 2008Co-Authors: Dirk Sibbing, Julia Stegherr, Wolfgang Latz, Werner Koch, Julinda Mehilli, Katharina Dorrler, Tanja Morath, Albert Schomig, Adnan Kastrati, Nicolas Von BeckerathAbstract:Aims Several studies have demonstrated that the mutant *2 allele of the CYP2C19 681G>A loss-of-function polymorphism is associated with diminished metabolization of clopidogrel into its active Thiol Metabolite and an attenuated platelet response to clopidogrel treatment. It is not known whether patients carrying the mutant CYP2C19*2 allele have a higher risk of stent thrombosis (ST) compared with homozygous CYP2C19*1 wild-type allele carriers following percutaneous coronary intervention (PCI). The aim of this study was to assess the impact of the CYP2C19 681G>A loss-of-function polymorphism on ST following PCI performed after pre-treatment with clopidogrel. Methods and results The study population included 2485 consecutive patients undergoing coronary stent placement after pre-treatment with 600 mg of clopidogrel. Genotypes were determined with a TaqMan assay. The primary endpoint of the study was the incidence of definite ST within 30 days following PCI. Of the patients studied, 1805 (73%) were CYP2C19 wild-type homozygotes (\*1/\*1) and 680 (27%) carried at least one *2 allele (\*1/\*2 or \*2/\*2). The cumulative 30-day incidence of ST was significantly higher in CYP2C19*2 allele carriers (\*1/\*2 or \*2/\*2) vs. CYP2C19 wild-type homozygotes (\*1/\*1) [10 patients (1.5%) in CYP2C19*2 allele carriers vs. 7 (0.4%) in CYP2C19 wild-type homozygotes (\*1/\*1), HR 3.81, 95% CI 1.45–10.02, P = 0.007; P = 0.006 after adjustment for confounding variables]. The risk of ST was highest (2.1%) in patients with the CYP2C19 \*2/\*2 genotype ( P = 0.002). Conclusion CYP2C19*2 carrier status is significantly associated with an increased risk of ST following coronary stent placement.
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absorption metabolization and antiplatelet effects of 300 600 and 900 mg loading doses of clopidogrel results of the isar choice intracoronary stenting and antithrombotic regimen choose between 3 high oral doses for immediate clopidogrel effect trial
Circulation, 2005Co-Authors: Nicolas Von Beckerath, Adnan Kastrati, Dirk Taubert, Gisela Pogatsamurray, Edgar Schomig, Albert SchomigAbstract:Background— For patients undergoing percutaneous coronary intervention, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is currently recommended. It is unknown, though, whether loading doses higher than 600 mg exert additional suppression of platelet function. Methods and Results— Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active Thiol Metabolite, unchanged clopidogrel, and the inactive carboxyl Metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active Metabolite, clopidogrel, and the carboxyl Metabolite compared with loading with 300 mg ...
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absorption metabolization and antiplatelet effects of 300 600 and 900 mg loading doses of clopidogrel results of the isar choice intracoronary stenting and antithrombotic regimen choose between 3 high oral doses for immediate clopidogrel effect trial
Circulation, 2005Co-Authors: Nicolas Von Beckerath, Adnan Kastrati, Dirk Taubert, Gisela Pogatsamurray, Edgar Schomig, Albert SchomigAbstract:BACKGROUND: For patients undergoing percutaneous coronary intervention, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is currently recommended. It is unknown, though, whether loading doses higher than 600 mg exert additional suppression of platelet function. METHODS AND RESULTS: Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active Thiol Metabolite, unchanged clopidogrel, and the inactive carboxyl Metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active Metabolite, clopidogrel, and the carboxyl Metabolite compared with loading with 300 mg (P or =0.38) and no further suppression of adenosine diphosphate-induced (5 and 20 micromol/L) platelet aggregation 4 hours after drug administration was achieved when compared with administration of 600 mg (P=0.59 and 0.39). CONCLUSIONS: Single doses of clopidogrel higher than 600 mg are not associated with an additional significant suppression of platelet function because of limited clopidogrel absorption.
Nicolas Von Beckerath - One of the best experts on this subject based on the ideXlab platform.
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cytochrome p450 2c19 loss of function polymorphism and stent thrombosis following percutaneous coronary intervention
European Heart Journal, 2008Co-Authors: Dirk Sibbing, Julia Stegherr, Wolfgang Latz, Werner Koch, Julinda Mehilli, Katharina Dorrler, Tanja Morath, Albert Schomig, Adnan Kastrati, Nicolas Von BeckerathAbstract:Aims Several studies have demonstrated that the mutant *2 allele of the CYP2C19 681G>A loss-of-function polymorphism is associated with diminished metabolization of clopidogrel into its active Thiol Metabolite and an attenuated platelet response to clopidogrel treatment. It is not known whether patients carrying the mutant CYP2C19*2 allele have a higher risk of stent thrombosis (ST) compared with homozygous CYP2C19*1 wild-type allele carriers following percutaneous coronary intervention (PCI). The aim of this study was to assess the impact of the CYP2C19 681G>A loss-of-function polymorphism on ST following PCI performed after pre-treatment with clopidogrel. Methods and results The study population included 2485 consecutive patients undergoing coronary stent placement after pre-treatment with 600 mg of clopidogrel. Genotypes were determined with a TaqMan assay. The primary endpoint of the study was the incidence of definite ST within 30 days following PCI. Of the patients studied, 1805 (73%) were CYP2C19 wild-type homozygotes (\*1/\*1) and 680 (27%) carried at least one *2 allele (\*1/\*2 or \*2/\*2). The cumulative 30-day incidence of ST was significantly higher in CYP2C19*2 allele carriers (\*1/\*2 or \*2/\*2) vs. CYP2C19 wild-type homozygotes (\*1/\*1) [10 patients (1.5%) in CYP2C19*2 allele carriers vs. 7 (0.4%) in CYP2C19 wild-type homozygotes (\*1/\*1), HR 3.81, 95% CI 1.45–10.02, P = 0.007; P = 0.006 after adjustment for confounding variables]. The risk of ST was highest (2.1%) in patients with the CYP2C19 \*2/\*2 genotype ( P = 0.002). Conclusion CYP2C19*2 carrier status is significantly associated with an increased risk of ST following coronary stent placement.
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absorption metabolization and antiplatelet effects of 300 600 and 900 mg loading doses of clopidogrel results of the isar choice intracoronary stenting and antithrombotic regimen choose between 3 high oral doses for immediate clopidogrel effect trial
Circulation, 2005Co-Authors: Nicolas Von Beckerath, Adnan Kastrati, Dirk Taubert, Gisela Pogatsamurray, Edgar Schomig, Albert SchomigAbstract:BACKGROUND: For patients undergoing percutaneous coronary intervention, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is currently recommended. It is unknown, though, whether loading doses higher than 600 mg exert additional suppression of platelet function. METHODS AND RESULTS: Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active Thiol Metabolite, unchanged clopidogrel, and the inactive carboxyl Metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active Metabolite, clopidogrel, and the carboxyl Metabolite compared with loading with 300 mg (P or =0.38) and no further suppression of adenosine diphosphate-induced (5 and 20 micromol/L) platelet aggregation 4 hours after drug administration was achieved when compared with administration of 600 mg (P=0.59 and 0.39). CONCLUSIONS: Single doses of clopidogrel higher than 600 mg are not associated with an additional significant suppression of platelet function because of limited clopidogrel absorption.
Patrick M Dansette - One of the best experts on this subject based on the ideXlab platform.
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Cytochromes P450 Catalyze Both Steps of the Major Pathway of Clopidogrel Bioactivation, whereas Paraoxonase Catalyzes the Formation of a Minor Thiol Metabolite Isomer
2016Co-Authors: Patrick M Dansette, Gildas Bertho, Julien Rosi, Daniel MansuyAbstract:The mechanism generally admitted for the bioactivation of the antithrombotic prodrug, clopidogrel, is its two-step enzymatic conversion into a biologically active Thiol Metabolite. The first step is a classical cytochrome P450 (P450)-dependent monooxygenation of its thiophene ring leading to 2-oxo-clopidogrel, a Thiolactone Metabolite. The second step was described as a P450-dependent oxidative opening of the Thiolactone ring of 2-oxo-clopidogrel, with intermediate formation of a reactive sulfenic acid Metabolite that is eventually reduced to the corresponding Thiol 4b. A very recent paper published in Nat. Med. (Bouman et al., (2011) 17, 110) reported that the second step of clopidogrel bioactivation was not catalyzed by P450 enzymes but by paraoxonase-1(PON-1) and that PON-1 was a major determinant of clopidogrel efficacy. The results described in the present article show that there are two metabolic pathways for the opening of the Thiolactone ring of 2-oxo-clopidogrel. The major one, that was previously described, results from a P450-dependent redox bioactivation of 2-oxo-clopidogrel and leads to 4b cis, two previously reported Thiol diastereomers bearing an exocyclic double bond. The second, minor one, results from a hydrolysis of 2-oxo-clopidogrel, which seems to be dependent on PON-1, and leads to an isomer of 4b cis, 4b "endo", in which the double bond has migrated from an exocyclic to an endocyclic position in the piperidine ring. These results were obtained from a detailed study of the metabolism of 2-oxo-clopidogrel by human liver microsomes and human sera and analysis by HPLC-MS under conditions allowing a complete separation of the Thiol Metabolite isomers, either as such or after derivatization with 3′-methoxy phenacyl bromide or N-ethyl maleimide (NEM). These results also show that the major bioactive Thiol isomer found in the plasma of clopidogrel-treated patients derives from 2-oxo-clopidogrel by the P450-dependent pathway. Finally, chemical experiments on 2-oxo-clopidogrel showed that this Thiolactone is in equilibrium with its tautomer having a double bond inside the piperidine ring and that nucleophiles such as CH3O– preferentially react on the thioester function of this tautomer. This allowed us to understand why 4b cis has to be formed via an oxidative opening of 2-oxo-clopidogrel Thiolactone, whereas a hydrolytic opening of this Thiolactone ring leads to the "endo" Thiol isomer 4b "endo"
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bioactivation of clopidogrel and prasugrel factors determining the stereochemistry of the Thiol Metabolite double bond
Chemical Research in Toxicology, 2015Co-Authors: Patrick M Dansette, Dan Levent, Assia Hessani, Daniel MansuyAbstract:The antithrombotics of the tetrahydrothienopyridine series, clopidogrel and prasugrel, are prodrugs that must be metabolized in two steps to become pharmacologically active. The first step is the formation of a Thiolactone Metabolite. The second step is a further oxidation with the formation of a Thiolactone sulfoxide whose hydrolytic opening leads to a sulfenic acid that is eventually reduced into the corresponding active cis Thiol. Very few data were available on the formation of the isomer of the active cis Thiol having a trans configuration of the double bond, the most striking result in that regard being that both cis and trans Thiols were formed upon the metabolism of clopidogrel by human liver microsomes in the presence of glutathione (GSH), whereas only the cis Thiol was detected in the sera of patients treated with this drug. This article shows that trans Thiols are also formed upon the microsomal metabolism of prasugrel or its Thiolactone Metabolite in the presence of GSH and that Metabolites ha...
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Thiolactone Sulfoxides as New Reactive Metabolites Acting as Bis-Electrophiles: Implication in Clopidogrel and Prasugrel Bioactivation
2013Co-Authors: Patrick M Dansette, Gildas Bertho, Dan Levent, Assia Hessani, Daniel MansuyAbstract:The antithrombotics of the tetrahydrothienopyridine series, clopidogrel and prasugrel, are prodrugs that must be metabolized in two steps to become pharmacologically active. The first step is the formation of a Thiolactone Metabolite. The second step is a cytochrome P450 (P450)-dependent oxidation of this Thiolactone resulting in the formation of a sulfenic acid that is eventually reduced into the corresponding active Thiol. It has been postulated that the sulfenic acid Metabolite resulted from a nucleophilic attack of water on a highly reactive Thiolactone sulfoxide derived from P450-dependent oxidation of the Thiolactone primary Metabolite. The data described in the present article are in complete agreement with this proposition as they show that it was possible to trap these Thiolactone sulfoxides by a series of nucleophiles such as amines, Thiols, or cyclopentane-1,3-dione (CPDH), an equivalent of dimedone that is used as a sulfenic acid trapping agent. HPLC-MS studies showed that various bis-adducts having incorporated two nucleophile molecules were formed in these reactions. One of them that resulted from the oxidation of 2-oxo-prasugrel by human liver microsomes in the presence of ethanolamine and CPDH was isolated and completely characterized by 1H and 13C NMR spectroscopy in addition to MS and MS2 spectrometry. All Metabolites derived from an attack of H2O or an amine at the CO carbon of the intermediate Thiolactone sulfoxide existed as a mixture of two diastereomers having a cis configuration of the double bond, whereas those formed in the presence of Thiols appeared as a mixture of four diastereomers with a cis or trans configuration of the double bond. This led us to propose tentative mechanisms for the previously reported formation of trans isomers of the active Thiol Metabolite of clopidogrel upon microsomal metabolism of this antithrombotic in the presence of Thiols. The results described in this article showed that Thiolactone sulfoxides are formed as reactive Metabolites during the metabolism of clopidogrel and prasugrel and are able to react as bis-electrophiles with a variety of nucleophiles. The possible implications of the formation of these reactive Metabolites in the pharmacological and/or secondary toxic effects of these drugs remain to be studied
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cytochromes p450 catalyze both steps of the major pathway of clopidogrel bioactivation whereas paraoxonase catalyzes the formation of a minor Thiol Metabolite isomer
Chemical Research in Toxicology, 2012Co-Authors: Patrick M Dansette, Gildas Bertho, Julien Rosi, Daniel MansuyAbstract:The mechanism generally admitted for the bioactivation of the antithrombotic prodrug, clopidogrel, is its two-step enzymatic conversion into a biologically active Thiol Metabolite. The first step is a classical cytochrome P450 (P450)-dependent monooxygenation of its thiophene ring leading to 2-oxo-clopidogrel, a Thiolactone Metabolite. The second step was described as a P450-dependent oxidative opening of the Thiolactone ring of 2-oxo-clopidogrel, with intermediate formation of a reactive sulfenic acid Metabolite that is eventually reduced to the corresponding Thiol 4b. A very recent paper published in Nat. Med. (Bouman et al., (2011) 17, 110) reported that the second step of clopidogrel bioactivation was not catalyzed by P450 enzymes but by paraoxonase-1(PON-1) and that PON-1 was a major determinant of clopidogrel efficacy. The results described in the present article show that there are two metabolic pathways for the opening of the Thiolactone ring of 2-oxo-clopidogrel. The major one, that was previousl...
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metabolic oxidative cleavage of thioesters evidence for the formation of sulfenic acid intermediates in the bioactivation of the antithrombotic prodrugs ticlopidine and clopidogrel
Chemical Research in Toxicology, 2009Co-Authors: Patrick M Dansette, Julie Libraire, Gildas Bertho, Daniel MansuyAbstract:Metabolic cleavage of the CO-S bond of some thioesters RCOSR' with the formation of RCOOH requires a monooxygenase-dependent oxidative activation of this bond. The nature of the S-containing product(s) resulting from this cleavage remains unclear in most cases. This communication provides the first evidence for the formation of sulfenic acid intermediates 4a and 4b during the oxidative cleavage of the CO-S bond of Thiolactone Metabolites 2a and 2b of antithrombotic prodrugs, ticlopidine and clopidogrel, by rat and human liver microsomes. These intermediates have been trapped by dimedone, and the corresponding adducts 5a and 5b have been characterized by mass spectrometry (MS) and (1)H and (13)C NMR spectroscopy. Their formation is monooxygenase-dependent and almost completely inhibited by microsomal cytochrome P450 inhibitors. Moreover, they were also formed upon incubation with microsomes containing recombinant human P450 3A4, 3A5, 2C8, 2C9, 2C19, 2D6, or 1A2. In the presence of Thiols such as mercaptoethanol, N-acetylcysteine, or glutathione, microsomal incubations of 2a led to mixed disulfides that have been characterized by MS and should result from reaction of 4a with these Thiols. At high Thiol concentrations, one observed in HPLC-MS the formation of a product exhibiting the MS expected for the previously described Thiol Metabolite 3a, a reduction product of 4a that has been reported as the pharmacologically active Metabolite of ticlopidine. These data provide the first evidence for the formation of sulfenic acid reactive Metabolites upon P450-catalyzed oxidative cleavage of thioesters. They also provide a first detailed mechanism for the previously described formation of pharmacologically active Thiols such as 3a upon oxidative metabolism of ticlopidine and clopidogrel.