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Schenk I, Machnik M, Broussou D, Meuly A, Roques BB, Lallemand E, Düe M, Röttgen H, Lagershausen H, Toutain PL, Thevis M. Kinetic disposition of diazepam and its metabolites after intravenous administration of diazepam in the horse: Relevance for doping control. J Vet Pharmacol Ther 2021; 44:733-744. [PMID: 34115414 DOI: 10.1111/jvp.12991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 04/08/2021] [Accepted: 05/19/2021] [Indexed: 01/11/2023]
Abstract
In horses, the benzodiazepine diazepam (DIA) is used as sedative for pre-medication or as an anxiolytic to facilitate horse examinations. As the sedative effects can also be abused for doping purposes, DIA is prohibited in equine sports. DIA is extensively metabolized to several active metabolites such as nordazepam, temazepam and oxazepam (OXA). For veterinarians, taking into account the detection times of DIA and its active metabolites is needed for minimizing the risk of an anti-doping rule violation. Therefore, a pharmacokinetic study on 6 horses was conducted using a single intravenous (IV) dose of 0.2 mg/kg DIA Plasma and urine samples were collected at specified intervals until 16 and 26 days post-administration, respectively. Samples were analysed by a sensitive liquid chromatography-electrospray ionization/tandem mass spectrometry method. DIA showed a triphasic elimination pattern in the horse. The mean plasma clearance of DIA was 5.9 ml/min/kg, and the plasma elimination half-life in the terminal phase was 19.9 h. Applying the Toutain model approach, an effective plasma concentration of DIA was estimated at 24 ng/ml, and irrelevant plasma concentration (IPC) and irrelevant urine concentration (IUC) were computed to 0.047 and 0.1 ng/ml, respectively. The detection time according to the European Horserace Scientific Liaison Committee (EHSLC), that is the time for which observed DIA plasma concentrations of all investigated horses were below the IPC was 10 days. Using Monte Carlo Simulations, it was estimated that concentrations of DIA in plasma would fall below the IPC 18 days after the DIA administration for 90% of horses. However, in the present study, a single administration of DIA could be detected for 24 days in urine via the presence of OXA, its dominant metabolite.
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Affiliation(s)
- Ina Schenk
- Institute of Biochemistry, Center for Preventive Doping Research, German Sport University Cologne, Cologne, Germany
| | - Marc Machnik
- Institute of Biochemistry, Center for Preventive Doping Research, German Sport University Cologne, Cologne, Germany
| | - Diane Broussou
- INTHERES, INRAE, ENVT, Université de Toulouse, Toulouse, France
| | - Astrid Meuly
- INTHERES, INRAE, ENVT, Université de Toulouse, Toulouse, France
| | | | | | | | - Helma Röttgen
- Institute of Biochemistry, Center for Preventive Doping Research, German Sport University Cologne, Cologne, Germany
| | | | - Pierre-Louis Toutain
- INTHERES, INRAE, ENVT, Université de Toulouse, Toulouse, France.,Comparative Biomedical Sciences, The Royal Veterinary College, University of London, London, UK
| | - Mario Thevis
- Institute of Biochemistry, Center for Preventive Doping Research, German Sport University Cologne, Cologne, Germany
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Kim KH, Park JW, Yang YM, Song KD, Cho BW. Effect of methylsulfonylmethane on oxidative stress and CYP3A93 expression in fetal horse liver cells. Anim Biosci 2020; 34:312-319. [PMID: 32898949 PMCID: PMC7876717 DOI: 10.5713/ajas.20.0061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/28/2020] [Indexed: 12/13/2022] Open
Abstract
Objective Stress-induced cytotoxicity caused by xenobiotics and endogenous metabolites induces the production of reactive oxygen species and often results in damage to cellular components such as DNA, proteins, and lipids. The cytochrome P450 (CYP) family of enzymes are most abundant in hepatocytes, where they play key roles in regulating cellular stress responses. We aimed to determine the effects of the antioxidant compound, methylsulfonylmethane (MSM), on oxidative stress response, and study the cytochrome P450 family 3 subfamily A (CYP3A) gene expression in fetal horse hepatocytes. Methods The expression of hepatocyte markers and CYP3A family genes (CYP3A89, CYP3A93, CYP3A94, CYP3A95, CYP3A96, and CYP3A97) were assessed in different organ tissues of the horse and fetal horse liver-derived cells (FHLCs) using quantitative reverse transcription polymerase chain reaction. To elucidate the antioxidant effects of MSM on FHLCs, cell viability, levels of oxidative markers, and gene expression of CYP3A were investigated in H2O2-induced oxidative stress in the presence and absence of MSM. Results FHLCs exhibited features of liver cells and simultaneously maintained the typical genetic characteristics of normal liver tissue; however, the expression profiles of some liver markers and CYP3A genes, except that of CYP3A93, were different. The expression of CYP3A93 specifically increased after the addition of H2O2 to the culture medium. MSM treatment reduced oxidative stress as well as the expression of CYP3A93 and heme oxygenase 1, an oxidative marker in FHLCs. Conclusion MSM could reduce oxidative stress and hepatotoxicity in FHLCs by altering CYP3A93 expression and related signaling pathways.
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Affiliation(s)
- Kyoung Hwan Kim
- Department of Animal Science, College of Natural Resources and Life Sciences, Pusan National University, Miryang 50463, Korea.,Life and Industry Convergence Research Institute, Pusan National University, Miryang 50463, Korea
| | - Jeong-Woong Park
- Department of Animal Science, College of Natural Resources and Life Sciences, Pusan National University, Miryang 50463, Korea
| | - Young Mok Yang
- Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Chungju 27478, Korea
| | - Ki-Duk Song
- Department of Agriculture Convergence Technology, Jeonbuk National University, Jeonju 54896, Korea
| | - Byung-Wook Cho
- Department of Animal Science, College of Natural Resources and Life Sciences, Pusan National University, Miryang 50463, Korea.,Life and Industry Convergence Research Institute, Pusan National University, Miryang 50463, Korea
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Vimercati S, Elli S, Jagannathan V, Pandey AV, Peduto N, Leeb T, Mevissen M. In silico and in vitro analysis of genetic variants of the equine CYP3A94, CYP3A95 and CYP3A97 isoenzymes. Toxicol In Vitro 2019; 60:116-124. [PMID: 31108125 DOI: 10.1016/j.tiv.2019.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/08/2019] [Accepted: 05/14/2019] [Indexed: 11/28/2022]
Abstract
Cytochrome P450 enzymes (CYPs) of the equine CYP3A subfamily are predominantly involved in drug metabolism. In this study, genetic variants of the equine CYP3A94, CYP3A95, and CYP3A97 were identified and characterized using in silico modeling and in vitro enzyme kinetics. The genomes of 81 horses were sequenced to obtain the genetic variants. Structural CYP modifications of the most frequent variants were analyzed in silico using the 3D-structures predicted by homology modeling. Enzyme kinetic analyses were performed using testosterone as substrate. Twenty genetic variants were found including five missense variants (CYP3A94:p.Asp217Asn, CYP3A95:p.Asp214His, CYP3A95:p.Ser392Thr, CYP3A97:p.Ile119Thr, CYP3A97:p.Met500Val) with a higher percentage of minor allele frequency (MAF) (range 0.2-0.4). A splice-site variant (c.798 + 1G > A) in CYP3A94, likely to generate a truncated protein, was found in 50% of the horses. CYP3A94:p.Asp217Asn and CYP3A95:p.Asp214His were localized on the CYP F-α-helix, an important region for the substrate interactions in the human CYP3A4. Testosterone 2β-hydroxylation was diminished in CYP3A94217Asn and CYP3A95392Thr. Ketoconazole inhibited 2β-hydroxylation differently in the five variants with the most pronounced inhibition obtained for CYP3A95392Thr. In vitro and in silico analyses of genetic variants allow unraveling structural features in equine CYPs that correlate with changes in the CYP activity.
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Affiliation(s)
- S Vimercati
- Veterinary Pharmacology and Toxicology, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, 3012 Bern, Switzerland.
| | - S Elli
- Istituto di Ricerche Chimiche e Biochimiche G. Ronzoni, Via G. Colombo 81, 20133 Milano, Italy.
| | - V Jagannathan
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland.
| | - A V Pandey
- Department of Pediatrics, Division of Pediatric Endocrinology and Diabetology, University Children's Hospital, Bern, Switzerland.
| | - N Peduto
- Veterinary Pharmacology and Toxicology, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, 3012 Bern, Switzerland.
| | - T Leeb
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland.
| | - M Mevissen
- Veterinary Pharmacology and Toxicology, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, 3012 Bern, Switzerland.
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Sandbaumhüter FA, Vimercati S, Thormann W, Mevissen M. Role of the equine CYP3A94, CYP3A95 and CYP3A97 in ketamine metabolism in presence of medetomidine, diazepam and methadone studied by enantioselective capillary electrophoresis. Toxicol In Vitro 2018; 50:242-248. [PMID: 29614330 DOI: 10.1016/j.tiv.2018.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 01/18/2018] [Accepted: 03/30/2018] [Indexed: 12/11/2022]
Abstract
The anesthetic ketamine is often combined with analgesics and benzodiazepines in equine medicine. Therefore, drug-drug interactions are possible. Enzyme kinetics for ketamine N-demethylation were determined using equine CYP3A94, CYP3A95 and CYP3A97, and the effect of medetomidine, diazepam and methadone on the ketamine metabolism was studied in vitro. Ketamine was incubated with the CYPs or equine liver microsomes (ELM) alone or in presence of medetomidine, diazepam and/or methadone for different times. Norketamine levels were determined using enantioselective capillary electrophoresis (CE) with highly sulfated γ-cyclodextrin as chiral selector. The three equine CYPs were demonstrated to be involved in ketamine N-demethylation and the kinetics can be described with the Michaelis-Menten model. Vmax values calculated for CYP3A94 and CYP3A97 were higher than for CYP3A95. The lowest Km value was found for CYP3A94. In contrast to diazepam and methadone, the α2-recepor agonist medetomidine diminished the norketamine formation significantly in CYP3A94 and CYP3A97. In ELM, increasing concentrations of diazepam inhibited the norketamine formation. Despite the differences in ketamine N-demethylation in combination with diazepam and methadone, the effect is unlikely to be of clinical relevance because ketamine and the other drugs do not have a small therapeutic margin.
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Affiliation(s)
- Friederike A Sandbaumhüter
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Murtenstrasse 35, Bern 3008, Switzerland
| | - Sara Vimercati
- Veterinary Pharmacology and Toxicology, Department of Clinical research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, Bern 3012, Switzerland
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Murtenstrasse 35, Bern 3008, Switzerland
| | - Meike Mevissen
- Veterinary Pharmacology and Toxicology, Department of Clinical research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Länggassstrasse 124, Bern 3012, Switzerland.
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Vimercati S, Büchi M, Zielinski J, Peduto N, Mevissen M. Testosterone metabolism of equine single CYPs of the 3A subfamily compared to the human CYP3A4. Toxicol In Vitro 2017; 41:83-91. [DOI: 10.1016/j.tiv.2017.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/06/2017] [Accepted: 02/20/2017] [Indexed: 01/02/2023]
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