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Franz M, Stalling T, Steinert H, Martens J. First catalyst-free CO 2 trapping of N-acyliminium ions under ambient conditions: sustainable multicomponent synthesis of thia- and oxazolidinyl carbamates. Org Biomol Chem 2018; 16:8292-8304. [PMID: 30221304 DOI: 10.1039/c8ob01865k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first trapping of N-acyliminium ions by in situ generated carbaminic acid (product of carbon dioxide (CO2) and amine) is reported. This catalyst-free reaction provides a convenient and feasible approach to prepare N-acyl thia- and oxazolidinyl carbamates with good functional-group compatibility and high efficiency under green conditions. Furthermore, the multicomponent method features a broad substrate scope, facile product diversification, smooth scale-up and notable potential for polymer applications.
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Affiliation(s)
- Max Franz
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, P. O. Box 2503, Carl-von-Ossietzky-Str. 9-11, 26111 Oldenburg, Germany.
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2
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Selby-Pham SNB, Miller RB, Howell K, Dunshea F, Bennett LE. Physicochemical properties of dietary phytochemicals can predict their passive absorption in the human small intestine. Sci Rep 2017; 7:1931. [PMID: 28512322 PMCID: PMC5434065 DOI: 10.1038/s41598-017-01888-w] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/13/2017] [Indexed: 01/02/2023] Open
Abstract
A diet high in phytochemical-rich plant foods is associated with reducing the risk of chronic diseases such as cardiovascular and neurodegenerative diseases, obesity, diabetes and cancer. Oxidative stress and inflammation (OSI) is the common component underlying these chronic diseases. Whilst the positive health effects of phytochemicals and their metabolites have been demonstrated to regulate OSI, the timing and absorption for best effect is not well understood. We developed a model to predict the time to achieve maximal plasma concentration (Tmax) of phytochemicals in fruits and vegetables. We used a training dataset containing 67 dietary phytochemicals from 31 clinical studies to develop the model and validated the model using three independent datasets comprising a total of 108 dietary phytochemicals and 98 pharmaceutical compounds. The developed model based on dietary intake forms and the physicochemical properties lipophilicity and molecular mass accurately predicts Tmax of dietary phytochemicals and pharmaceutical compounds over a broad range of chemical classes. This is the first direct model to predict Tmax of dietary phytochemicals in the human body. The model informs the clinical dosing frequency for optimising uptake and sustained presence of dietary phytochemicals in circulation, to maximise their bio-efficacy for positively affect human health and managing OSI in chronic diseases.
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Affiliation(s)
- Sophie N B Selby-Pham
- Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, 3010, Australia
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, 3030, Australia
| | | | - Kate Howell
- Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, 3010, Australia
| | - Frank Dunshea
- Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, 3010, Australia
| | - Louise E Bennett
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, 3030, Australia.
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3
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Judson PN, Long A, Murray E, Patel M. Assessing Confidence in Predictions Using Veracity and Utility - A Case Study on the Prediction of Mammalian Metabolism by Meteor Nexus. Mol Inform 2015; 34:284-91. [DOI: 10.1002/minf.201400184] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/17/2015] [Indexed: 11/12/2022]
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Greene RJ, Davis JA, Subramanian R, Deane MR, Emery MG, Slatter JG. Regiospecific and stereospecific triangulation of the structures of metabolites formed by sequential metabolism at multiple prochiral centers. Drug Metab Dispos 2012; 40:928-42. [PMID: 22328582 DOI: 10.1124/dmd.111.043166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Structures of in vivo secondary metabolites of a norbornane-containing drug candidate with multiple prochiral centers were triangulated, in a regio- and stereospecific fashion, using in vitro metabolism data from synthetic primary metabolites and in vivo metabolism data from the separate administration of a radiolabeled primary metabolite, [(14)C]-(S)-2-((1R,2S,4R,5S)-5-hydroxybicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (M1). A mass balance study on the 11β hydroxysteroid dehydrogenase type 1 enzyme inhibitor [(14)C]-(S)-2-((1S,2S,4R)-bicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (AMG 221) in rats was dosed at 2 mg/kg. Radioactivity was excreted mainly in urine. Metabolites of AMG 221 were quantified by high-performance liquid chromatography with radiometric detection and characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS). LC-MS/MS revealed at least 38 metabolites. Seven monohydroxylated metabolites mediated formation of the other 31 metabolites. Twenty-eight metabolites were identified regio- and stereo-specifically. Little parent drug was observed in urine or feces. Monohydroxy metabolite M1 was the major metabolite comprising 17 to 24% of excreted dose, and seven monohydroxy metabolites comprised 29 (male) and 37% (female) of dose. Of 11 quantifiable isobaric dihydroxy metabolites that comprised 8.3 (male) and 24% (female) of dose, 10 were identified regio- and stereospecifically by triangulation. A single trihydroxy metabolite comprised approximately 10% of dose. Complex secondary metabolism of drugs with multiple prochiral centers can be elucidated in a regio- and stereospecific fashion without NMR through synthesis and in vitro and in vivo studies on the metabolism of chiral primary oxidation products.
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Affiliation(s)
- Robert J Greene
- Pharmacokinetics and Drug Metabolism, Amgen Inc., 1201 Amgen Court West, Seattle, Washington 98119, USA
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5
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Vacondio F, Silva C, Mor M, Testa B. Qualitative structure-metabolism relationships in the hydrolysis of carbamates. Drug Metab Rev 2011; 42:551-89. [PMID: 20441444 DOI: 10.3109/03602531003745960] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The aims of this review were 1) to compile a large number of reliable literature data on the metabolic hydrolysis of medicinal carbamates and 2) to extract from such data a qualitative relation between molecular structure and lability to metabolic hydrolysis. The compounds were classified according to the nature of their substituents (R³OCONR¹R²), and a metabolic lability score was calculated for each class. A trend emerged, such that the metabolic lability of carbamates decreased (i.e., their metabolic stability increased), in the following series: Aryl-OCO-NHAlkyl >> Alkyl-OCO-NHAlkyl ~ Alkyl-OCO-N(Alkyl)₂ ≥ Alkyl-OCO-N(endocyclic) ≥ Aryl-OCO-N(Alkyl)₂ ~ Aryl-OCO-N(endocyclic) ≥ Alkyl-OCO-NHAryl ~ Alkyl-OCO-NHAcyl >> Alkyl-OCO-NH₂ > Cyclic carbamates. This trend should prove useful in the design of carbamates as drugs or prodrugs.
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Affiliation(s)
- Federica Vacondio
- Dipartimento Farmaceutico, Università degli Studi di Parma, Parma, Italy.
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6
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Jones LH, Allan G, Barba O, Burt C, Corbau R, Dupont T, Knöchel T, Irving S, Middleton DS, Mowbray CE, Perros M, Ringrose H, Swain NA, Webster R, Westby M, Phillips C. Novel Indazole Non-Nucleoside Reverse Transcriptase Inhibitors Using Molecular Hybridization Based on Crystallographic Overlays. J Med Chem 2009; 52:1219-23. [DOI: 10.1021/jm801322h] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lyn H. Jones
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Gill Allan
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Oscar Barba
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Catherine Burt
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Romuald Corbau
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Thomas Dupont
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Thorsten Knöchel
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Steve Irving
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Donald S. Middleton
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Charles E. Mowbray
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Manos Perros
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Heather Ringrose
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Nigel A. Swain
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Robert Webster
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Mike Westby
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Chris Phillips
- Discovery Chemistry, Discovery Biology, Pharmacokinetics, Dynamics, and Metabolism, Structural Biology, Molecular Informatics and Structure-Based Design, Sandwich Laboratories, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
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Dalvie D, Obach RS, Kang P, Prakash C, Loi CM, Hurst S, Nedderman A, Goulet L, Smith E, Bu HZ, Smith DA. Assessment of Three Human in Vitro Systems in the Generation of Major Human Excretory and Circulating Metabolites. Chem Res Toxicol 2009; 22:357-68. [DOI: 10.1021/tx8004357] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Deepak Dalvie
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - R. Scott Obach
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Ping Kang
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Chandra Prakash
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Cho-Ming Loi
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Susan Hurst
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Angus Nedderman
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Lance Goulet
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Evan Smith
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Hai-Zhi Bu
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
| | - Dennis A. Smith
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego California 92121, Pfizer Global Research and Development, Groton Connecticut 06340, and Pfizer Global Research and Development, Sandwich, Kent, United Kingdom
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8
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Vermeir M, Lachau-Durand S, Mannens G, Cuyckens F, van Hoof B, Raoof A. Absorption, Metabolism, and Excretion of Darunavir, a New Protease Inhibitor, Administered Alone and with Low-Dose Ritonavir in Healthy Subjects. Drug Metab Dispos 2009; 37:809-20. [DOI: 10.1124/dmd.108.024109] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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9
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Jones L, Allan G, Corbau R, Hay D, Middleton D, Mowbray C, Newman S, Perros M, Randall A, Vuong H, Webster R, Westby M, Williams D. Optimization of 5-Aryloxyimidazole Non-Nucleoside Reverse Transcriptase Inhibitors. ChemMedChem 2008; 3:1756-62. [DOI: 10.1002/cmdc.200800183] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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Roffey SJ, Obach RS, Gedge JI, Smith DA. What is the Objective of the Mass Balance Study? A Retrospective Analysis of Data in Animal and Human Excretion Studies Employing Radiolabeled Drugs. Drug Metab Rev 2008; 39:17-43. [PMID: 17364879 DOI: 10.1080/03602530600952172] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mass balance excretion studies in laboratory animals and humans using radiolabeled compounds represent a standard part of the development process for new drugs. From these studies, the total fate of drug-related material is obtained: mass balance, routes of excretion, and, with additional analyses, metabolic pathways. However, rarely does the mass balance in radiolabeled excretion studies truly achieve 100% recovery. Many definitions of cutoff criteria for mass balance that identify acceptable versus unacceptable recovery have been presented as ad hoc statements without a strong rationale. To address this, a retrospective analysis was undertaken to explore the overall performance of mass balance studies in both laboratory animal species and humans using data for 27 proprietary compounds within Pfizer and extensive review of published studies. The review has examined variation in recovery and the question of whether low recovery was a cause for concern in terms of drug safety. Overall, mean recovery was greater in rats and dogs than in humans. When the circulating half-life of total radioactivity is greater than 50 h, the recovery tends to be lower. Excretion data from the literature were queried as to whether drugs linked with toxicities associated with sequestration in tissues or covalent binding exhibit low mass balance. This was not the case, unless the sequestration led to a long elimination half-life of drug-related material. In the vast majority of cases, sequestration or concentration of drug-related material in an organ or tissue was without deleterious effect and, in some cases, was related to the pharmacological mechanism of action. Overall, from these data, recovery of radiolabel would normally be equal to or greater than 90%, 85%, and 80% in rat, dog, and human, respectively. Since several technical limitations can underlie a lack of mass balance and since mass balance data are not sensitive indicators of the potential for toxicity arising via tissue sequestration, absolute recovery in humans should not be used as a major decision criteria as to whether a radiolabeled study has met its objectives. Instead, the study should be seen as an integral part of drug development answering four principal questions: 1) Is the proposed clearance mechanism sufficiently supported by the identities of the drug-related materials in excreta, so as to provide a complete understanding of clearance and potential contributors to interpatient variability and drug-drug interactions? 2) What are the drug-related entities present in circulation that are the active principals contributing to primary and secondary pharmacology? 3) Are there findings (low extraction recovery of radiolabel from plasma, metabolite structures indicative of chemically reactive intermediates) that suggest potential safety issues requiring further risk assessment? 4) Do questions 2 and 3 have appropriate preclinical support in terms of pharmacology, safety pharmacology, and toxicology? Only if one or more of these four questions remain unanswered should additional mass balance studies be considered.
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Affiliation(s)
- Sarah J Roffey
- Pharmacokinetics, Dynamics, and Metabolism, Pfizer, Inc., Sandwich, Kent, UK
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11
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Ramanathan R, Alvarez N, Su AD, Chowdhury S, Alton K, Stauber K, Patrick J. Metabolism and excretion of loratadine in male and female mice, rats and monkeys. Xenobiotica 2008; 35:155-89. [PMID: 16019945 DOI: 10.1080/00498250500038906] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The metabolism and excretion of loratadine (LOR), a long-acting non-sedating antihistamine, have been evaluated in male and female mice, rats and monkeys. Following a single (8 mg kg-1) oral administration of [14C]LOR, radioactivity was predominantly eliminated in the faeces. Profiling and characterization of metabolites in plasma, bile, urine and faeces from male and female mice, rats and monkeys showed LOR to be extensively metabolized with quantitative species and gender differences in the observed metabolites. In all species investigated, the primary biotransformation of LOR involved decarboethoxylation to form desloratadine (DL), subsequent oxidation (hydroxylation and N-oxidation) and glucuronidation. More than 50 metabolites were profiled using liquid chromatography-mass spectrometry (LC-MS) with in-line flow scintillation analysis (FSA) and characterized using LC-MSn techniques. The major circulating metabolite in male rats is a DL derivative in which the piperidine ring was aromatized and oxidized to pyridine-N-oxide. Much lower levels of the pyridine-N-oxide metabolite were observed in female rat plasma. In contrast, the relative amount of DL was notably higher in female than in male rats. The major circulating metabolite in either gender of mouse and male monkey is a glucuronide conjugate of an aliphatic hydroxylated LOR; in the female monkey, the major circulating metabolite is formed through oxidation of the pyridine moiety and subsequent glucuronidation. Qualitatively similar metabolic profiles were observed in the mouse, rat and monkey urine and bile, and the metabolites characterized resulted from biotransformation of LOR to DL, hydroxylation of DL and subsequent glucuronide conjugation. 5-Hydroxy-desloratadine was the major faecal metabolite across all three species irrespective of gender.
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Affiliation(s)
- R Ramanathan
- Drug Metabolism and Pharmacokinetics, Schering-Plough Research Institute, Kenilworth, NJ 07033, USA.
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Bu HZ, Zhao P, Kang P, Pool WF, Wu EY, Shetty BV. Evaluation of Capravirine as a CYP3A Probe Substrate: In Vitro and in Vivo Metabolism of Capravirine in Rats and Dogs. Drug Metab Dispos 2007; 35:1593-602. [PMID: 17567732 DOI: 10.1124/dmd.107.016147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Metabolism of [(14)C]capravirine was studied via both in vitro and in vivo means in rats and dogs. Mass balance was achieved in rats and dogs, with mean total recovery of radioactivity >86% for each species. Capravirine was well absorbed in rats but only moderately so in dogs. The very low levels of recovered unchanged capravirine and the large number of metabolites observed in rats and dogs indicate that capravirine was eliminated predominantly by metabolism in both species. Capravirine underwent extensive metabolism via oxygenation reactions (predominant pathways in both species), depicolylation and carboxylation in rats, and decarbamation in dogs. The major circulating metabolites of capravirine were two depicolylated products in rats and three decarbamated products in dogs. However, none of the five metabolites was observed in humans, indicating significant species differences in terms of identities and relative abundances of circulating capravirine metabolites. Because the majority of in vivo oxygenated metabolites of capravirine were observed in liver microsomal incubations, the in vitro models provided good insight into the in vivo oxygenation pathways. In conclusion, the diversity (i.e., hydroxylation, sulfoxidation, sulfone formation, and N-oxidation), multiplicity (i.e., mono-, di-, tri-, and tetraoxygenations), and high enzymatic specificity (>90% contribution by CYP3A4 in humans, CYP3A1/2 in rats, and CYP3A12 in dogs) of the capravirine oxygenation reactions observed in humans, rats, and dogs in vivo and in vitro suggest that capravirine can be a useful CYP3A substrate for probing catalytic mechanisms and kinetics of CYP3A enzymes in humans and animal species.
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Affiliation(s)
- Hai-Zhi Bu
- Department of Pharmacokinetics, Dynamics, and Metabolism, Pfizer Global Research and Development, San Diego, CA 92121, USA.
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Bu HZ, Zhao P, Kang P, Pool WF, Wu EY. Identification of Enzymes Responsible for Primary and Sequential Oxygenation Reactions of Capravirine in Human Liver Microsomes. Drug Metab Dispos 2006; 34:1798-802. [PMID: 16914510 DOI: 10.1124/dmd.106.011189] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Capravirine, a new non-nucleoside reverse transcriptase inhibitor, undergoes extensive oxygenation reactions, including N-oxidation, sulfoxidation, sulfonation, and hydroxylation in humans. Numerous primary (mono-oxygenated) and sequential (di-, tri-, and tetraoxygenated) metabolites of capravirine are formed via the individual or combined oxygenation pathways. In this study, cytochrome P450 enzymes responsible for the primary and sequential oxygenation reactions of capravirine in human liver microsomes were identified at the specific pathway level. The total oxygenation of capravirine is mediated predominantly (>90%) by CYP3A4 and marginally (<10%) by CYP2C8, 2C9, and 2C19 in humans. Specifically, each of the two major mono-oxygenated metabolites C23 (sulfoxide) and C26 (N-oxide), is mediated predominantly (>90%) by CYP3A4 and slightly (<10%) by CYP2C8, the minor tertiary hydroxylated metabolite C19 by CYP3A4, 2C8, and 2C19, and the minor primary hydroxylated metabolite C20 by CYP3A4, 2C8, and 2C9. However, all sequential oxygenation reactions are mediated exclusively by CYP3A4. Due to their relatively insignificant contributions of C19 and C20 to total capravirine metabolism, no attempt was made to determine relative contributions of cytochrome P450 enzymes to the formation of the two minor metabolites.
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Affiliation(s)
- Hai-Zhi Bu
- Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego, CA 92121, USA.
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Bu HZ, Kang P, Zhao P, Pool WF, Wu EY. A SIMPLE SEQUENTIAL INCUBATION METHOD FOR DECONVOLUTING THE COMPLICATED SEQUENTIAL METABOLISM OF CAPRAVIRINE IN HUMANS. Drug Metab Dispos 2005; 33:1438-45. [PMID: 16006566 DOI: 10.1124/dmd.105.005413] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Capravirine, a non-nucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1, undergoes extensive oxygenations to numerous sequential metabolites in humans. Because several possible oxygenation pathways may be involved in the formation and/or sequential metabolism of a single metabolite, it is very difficult or even impossible to determine the definitive pathways and their relative contributions to the overall metabolism of capravirine using conventional approaches. For this reason, a human liver microsome-based "sequential incubation" method has been developed to deconvolute the complicated sequential metabolism of capravirine. In brief, the method includes three fundamental steps: 1) 30-min primary incubation of [(14)C]capravirine, 2) isolation of (14)C metabolites from the primary incubate, and 3) 30-min sequential incubation of each isolated (14)C metabolite supplemented with an ongoing (30 min) microsomal incubation with nonlabeled capravirine. Based on the extent of both the disappearance of the isolated precursor (14)C metabolites and the formation of sequential (14)C metabolites, definitive oxygenation pathways of capravirine were assigned. In addition, the percentage contribution of a precursor metabolite to the formation of each of its sequential metabolites (called sequential contribution) and the percentage contribution of a sequential metabolite formed from each of its precursor metabolites (called precursor contribution) were determined. An advantage of this system is that the sequential metabolism of each isolated (14)C metabolite can be monitored selectively by radioactivity in the presence of all relevant metabolic components (i.e., nonlabeled parent and its other metabolites). This methodology should be applicable to mechanistic studies of other compounds involving complicated sequential metabolic reactions when radiolabeled materials are available.
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Affiliation(s)
- Hai-Zhi Bu
- Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, San Diego, CA 92121, USA.
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