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White PA, Luijten M, Mishima M, Cox JA, Hanna JN, Maertens RM, Zwart EP. In vitro mammalian cell mutation assays based on transgenic reporters: A report of the International Workshop on Genotoxicity Testing (IWGT). MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 847:403039. [DOI: 10.1016/j.mrgentox.2019.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/26/2019] [Accepted: 04/06/2019] [Indexed: 02/07/2023]
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Ventura E, Gadaj A, Monteith G, Ripoche A, Healy J, Botrè F, Sterk SS, Buckley T, Mooney MH. Development and validation of a semi-quantitative ultra-high performance liquid chromatography-tandem mass spectrometry method for screening of selective androgen receptor modulators in urine. J Chromatogr A 2019; 1600:183-196. [DOI: 10.1016/j.chroma.2019.04.050] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/16/2019] [Accepted: 04/17/2019] [Indexed: 12/13/2022]
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Martin IJ, Hill SE, Baker JA, Deshmukh SV, Mulrooney EF. A Pharmacokinetic Modeling Approach to Predict the Contribution of Active Metabolites to Human Efficacious Dose. ACTA ACUST UNITED AC 2016; 44:1435-40. [PMID: 27260151 DOI: 10.1124/dmd.116.070391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/02/2016] [Indexed: 02/03/2023]
Abstract
A preclinical drug candidate, MRK-1 (Merck candidate drug parent compound), was found to elicit tumor regression in a mouse xenograft model. Analysis of samples from these studies revealed significant levels of two circulating metabolites, whose identities were confirmed by comparison with authentic standards using liquid chromatography-tandem mass spectrometry. These metabolites were found to have an in vitro potency similar to that of MRK-1 against the pharmacological target and were therefore thought to contribute to the observed efficacy. To predict this contribution in humans, a pharmacokinetic (PK) modeling approach was developed. At the mouse efficacious dose, the areas under the plasma concentration time curves (AUCs) of the active metabolites were normalized by their in vitro potency compared with MRK-1. These normalized metabolite AUCs were added to that of MRK-1 to yield a composite efficacious unbound AUC, expressed as "parent drug equivalents," which was used as the target AUC for predictions of the human efficacious dose. In vitro and preclinical PK studies afforded predictions of the PK of MRK-1 and the two active metabolites in human as well as the relative pathway flux to each metabolite. These were used to construct a PK model (Berkeley Madonna, version 8.3.18; Berkeley Madonna Inc., University of California, Berkeley, CA) and to predict the human dose required to achieve the target parent equivalent exposure. These predictions were used to inform on the feasibility of the human dose in terms of size, frequency, formulation, and likely safety margins, as well as to aid in the design of preclinical safety studies.
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Affiliation(s)
- Iain J Martin
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism, Merck Research Laboratories, Boston, Massachusetts
| | - Susan E Hill
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism, Merck Research Laboratories, Boston, Massachusetts
| | - James A Baker
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism, Merck Research Laboratories, Boston, Massachusetts
| | - Sujal V Deshmukh
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism, Merck Research Laboratories, Boston, Massachusetts
| | - Erin F Mulrooney
- Pharmacokinetics, Pharmacodynamics, and Drug Metabolism, Merck Research Laboratories, Boston, Massachusetts
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Rioux N, Mitchell LH, Tiller P, Plant K, Shaw J, Frost K, Ribich S, Moyer MP, Copeland RA, Chesworth R, Waters NJ. Structural and Kinetic Characterization of a Novel N-acetylated Aliphatic Amine Metabolite of the PRMT Inhibitor, EPZ011652. Drug Metab Dispos 2015; 43:936-43. [PMID: 25887455 DOI: 10.1124/dmd.115.064014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 04/17/2015] [Indexed: 01/11/2023] Open
Abstract
Pharmacokinetic and metabolite identification studies were conducted to understand the clearance pathways of EPZ011652 [(2-aminoethyl)(methyl)({3-[4-(propan-2-yloxy)phenyl]-1H-pyrazol-4-yl}methyl)amine], a potent protein arginine N-methyltransferase inhibitor. Metabolic clearance was the major pathway of EPZ011652 elimination in rats with structural elucidation of metabolites via liquid chromatography - mass spectrometry (LC-MS(n)) accurate mass measurement revealing the formation of a novel aliphatic N-acetylated metabolite (M1) located on the terminal nitrogen of the ethylene-diamine side chain. EPZ015564, a synthetic standard of the N-acetyl product, was prepared and was also generated by human and rat, but not dog hepatocytes. In rat hepatocytes, on incubation with EPZ011652, the concentration of EPZ015564 initially increased before decreasing with incubation time, suggesting that the metabolite is itself a substrate for other metabolizing enzymes, in agreement with the identification of metabolites M2, M3, and M4 in rat bile, all N-acetylated metabolites, undergoing sequential phase I (demethylation, oxidation) or phase II (sulfation) reactions. Reaction phenotyping with recombinant human N-acetyltransferase (NAT) isoforms revealed that both NAT1 and NAT2 are capable of acetylating EPZ011652, although with different catalytic efficiencies. Kinetic profiles of EPZ015564 formation followed classic Michaelis-Menten behavior with apparent Km values of >1000 μM for NAT1 and 165 ± 14.1 µM for NAT2. The in vitro intrinsic clearance for EPZ011652 by NAT2 (110 μL/min/mg) was 500-fold greater than by NAT1. In summary, we report the unusual N-acetylation of an aliphatic amine and discuss the implications for drug discovery and clinical development.
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Affiliation(s)
- Nathalie Rioux
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Lorna H Mitchell
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Philip Tiller
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Katie Plant
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Joanne Shaw
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Kerry Frost
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Scott Ribich
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Mikel P Moyer
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Robert A Copeland
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Richard Chesworth
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
| | - Nigel J Waters
- Epizyme, Cambridge, Massachusetts (N.R., L.H.M., S.R., M.P.M., R.A.C., R.C., N.J.W.); RMI Laboratories, North Wales, Pennsylvania (P.T.); and Cyprotex, Macclesfield, Cheshire, United Kingdom (K.P., J.S., K.F.)
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Loureiro AI, Soares-da-Silva P. Distribution and pharmacokinetics of etamicastat and its N-acetylated metabolite (BIA 5-961) in dog and monkey. Xenobiotica 2015; 45:903-11. [PMID: 25869244 DOI: 10.3109/00498254.2015.1024780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
1. The disposition etamicastat was evaluated in the Cynomolgus monkey after intravenous and oral administration of [(14)C]-etamicastat. The pharmacokinetics of etamicastat and its N-acetylated metabolite BIA 5-961 were also evaluated in monkeys and dogs. 2. In the monkey, 7 days after intravenous and oral administration of [(14)C]-etamicastat, 76.6-91.1% of the etamicastat-related radioactivity had been excreted mainly in urine. The radioactivity peaked in plasma between 4- and 8-h post-dosing followed by a quick decline and a slow terminal phase (half-life of 68.7 h). The calculated oral bioavailability for etamicastat was 46.1%. Etamicastat was quickly absorbed in monkeys and dogs with a half-life ranging from 5.2 to 9.9 h in monkeys and 6.9 to 11.4 h in dogs over. 3. The N-acetylated metabolite of etamicastat, represented 4-7% of the extent of exposure of etamicastat in the monkey, but was not found detectable in dogs. Gender did not influence etamicastat exposure and the concentration versus time curves fitted a dose-dependent pharmacokinetics in the dog, but not in the monkey. 4. In conclusion, etamicastat is rapidly absorbed and primarily excreted via urine in monkeys. Similarly, to humans, monkeys, unlike dogs, N-acetylate etamicastat and evidence that etamicastat pharmacokinetics is less than dose proportional.
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Affiliation(s)
- A I Loureiro
- a Department of Research and Development , BIAL - Portela & Ca. S.A., S Mamede do Coronado , Portugal and
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Cardiovascular safety pharmacology profile of etamicastat, a novel peripheral selective dopamine-ß-hydroxylase inhibitor. Eur J Pharmacol 2015; 750:98-107. [DOI: 10.1016/j.ejphar.2015.01.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 01/18/2015] [Accepted: 01/20/2015] [Indexed: 11/24/2022]
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Loureiro AI, Fernandes-Lopes C, Bonifácio MJ, Wright LC, Soares-da-Silva P. N-Acetylation of Etamicastat, a Reversible Dopamine-β-Hydroxylase Inhibitor. Drug Metab Dispos 2013; 41:2081-6. [DOI: 10.1124/dmd.113.053736] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Abstract
Personalized medicine is based on intraspecies differences. It is axiomatic that small differences in genetic make-up can result in dramatic differences in response to drugs or disease. To express this in more general terms: in any given complex system, small changes in initial conditions can result in dramatically different outcomes. Despite human variability and intraspecies variation in other species, nonhuman species are still the primary model for ascertaining data for humans. We call this practice into question and conclude that human-based research should be the primary means for obtaining data about human diseases and responses to drugs.
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Affiliation(s)
| | - Andre Menache
- Americans For Medical Advancement, 2251 Refugio Rd, Goleta, CA 93117, USA
| | - Mark J Rice
- Department of Anesthesiology, University of Florida College of Medicine, PO Box 100254, Gainesville, FL 32610-0254, USA
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Zhang H, Liu Q, Fan T, Fang Y, Li Y, Wang G. Metabolism and disposition of a novel antineoplastic JS-38 (Benzamide, N-[4-(2,4-dimethoxyphenyl)-4,5-dihydro-5-oxo-1,2-dithiolo[4,3-b]pyrrol-6-yl]-3,5-bis (trifluoromethyl)-(9Cl)) in rats. Eur J Drug Metab Pharmacokinet 2011; 37:45-56. [PMID: 21805208 DOI: 10.1007/s13318-011-0055-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 07/08/2011] [Indexed: 11/28/2022]
Abstract
The metabolism and catabolism of a novel antineoplastic (ID code JS-38),Benzamide, N-[4-(2,4-dimethoxyphenyl)-4,5-dihydro-5-oxo-1,2-dithiolo[4,3-b]pyrrol-6-yl]-3,5-bis (trifluoromethyl)-(9Cl), were investigated in Wistar rats (3 female, 3 male). LC/UV, LC/MS, LC/MS/MS, NMR and acid hydrolysis methods showed that the metabolic process of JS-38 consists of a series of acetylation and glucoronation that form a metabolic product with a unique pharmacologic property of accelerating bone-marrow cell formation, and also showed a novel metabolic pathway of being acetylated and glucuronated in series.
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Affiliation(s)
- Hong Zhang
- Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai, China.
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Mohler ML, Bohl CE, Jones A, Coss CC, Narayanan R, He Y, Hwang DJ, Dalton JT, Miller DD. Nonsteroidal Selective Androgen Receptor Modulators (SARMs): Dissociating the Anabolic and Androgenic Activities of the Androgen Receptor for Therapeutic Benefit. J Med Chem 2009; 52:3597-617. [DOI: 10.1021/jm900280m] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael L. Mohler
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Casey E. Bohl
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Amanda Jones
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Christopher C. Coss
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Ramesh Narayanan
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Yali He
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Dong Jin Hwang
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - James T. Dalton
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
| | - Duane D. Miller
- Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, and Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Memphis, Tennessee 38163
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Gao W, Kim J, Dalton JT. Pharmacokinetics and pharmacodynamics of nonsteroidal androgen receptor ligands. Pharm Res 2007; 23:1641-58. [PMID: 16841196 PMCID: PMC2072875 DOI: 10.1007/s11095-006-9024-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Accepted: 03/31/2006] [Indexed: 10/24/2022]
Abstract
Testosterone and structurally related anabolic steroids have been used to treat hypogonadism, muscle wasting, osteoporosis, male contraception, cancer cachexia, anemia, and hormone replacement therapy in aging men or age-related frailty; while antiandrogens may be useful for treatment of conditions like acne, alopecia (male-pattern baldness), hirsutism, benign prostatic hyperplasia (BPH) and prostate cancer. However, the undesirable physicochemical and pharmacokinetic properties of steroidal androgen receptor (AR) ligands limited their clinical use. Nonsteroidal AR ligands with improved pharmacological and pharmacokinetic properties have been developed to overcome these problems. This review focuses on the pharmacokinetics, metabolism, and pharmacology of clinically used and emerging nonsteroidal AR ligands, including antagonists, agonists, and selective androgen receptor modulators.
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Affiliation(s)
- Wenqing Gao
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, Ohio 43210, USA
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Perera MA, Yin D, Wu D, Chan KK, Miller DD, Dalton J. In Vivo Metabolism and Final Disposition of a Novel Nonsteroidal Androgen in Rats and Dogs. Drug Metab Dispos 2006; 34:1713-21. [PMID: 16815963 DOI: 10.1124/dmd.106.009985] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Compound S-4 (S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide) is a novel nonsteroidal androgen agonist that mimics many of the beneficial pharmacologic effects of testosterone with lesser effects on the prostate. S-4 demonstrated high androgen receptor binding affinity as well as anabolic specificity during in vivo pharmacologic studies in rats, identifying it as the first member of a new class of selective androgen receptor modulators. The purpose of these studies was to determine the pharmacokinetics and metabolism of S-4 in dogs. S-4 showed linear pharmacokinetics after both intravenous (i.v.) and oral (p.o.) administrations at pharmacologically relevant doses, with a mean clearance of 4.6 ml/min/kg and a mean half-life of about 200 min. It is interesting that dose-dependent oral bioavailability was seen. However, at pharmacologically relevant doses, the oral bioavailability of S-4 was 91%. Species differences were observed in S-4 metabolism; the major metabolic pathway for S-4 in dogs was deacetylation of the B-ring acetamide group and reduction of the A-ring nitro group, whereas the major metabolic pathway for S-4 in rats was hydrolysis on the amide bond and reduction of the A-ring nitro group. In addition, oxidative metabolites and phase II metabolites were identified in both rats and dogs. These studies demonstrate that S-4 maintains its promising pharmacokinetic properties in dogs (i.e., high oral bioavailability and linear kinetics) and is largely eliminated via hepatic metabolism by both phase I and phase II enzymes.
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Affiliation(s)
- Minoli A Perera
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, 500 West 12th Ave., Columbus, OH 43210, USA
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Gao W, Wu Z, Bohl CE, Yang J, Miller DD, Dalton JT. Characterization of the in vitro metabolism of selective androgen receptor modulator using human, rat, and dog liver enzyme preparations. Drug Metab Dispos 2005; 34:243-53. [PMID: 16272404 PMCID: PMC2039882 DOI: 10.1124/dmd.105.007112] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Compound S4 [S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide] is a novel nonsteroidal selective androgen receptor modulator that demonstrates tissue-selective androgenic and anabolic effects. The purpose of this in vitro study was to identify the phase I metabolites, potential species differences in metabolism, and the cytochromes P450 (P450s) involved in the phase I metabolism of S4 using 14C-S4, recombinant P450s, and other liver enzyme preparations from human, rat, and dog. The major phase I metabolism pathways of S4 in humans were identified as deacetylation of the B-ring acetamide group, hydrolysis of the amide bond, reduction of the A-ring nitro group, and oxidation of the aromatic rings, with deacetylation being the predominant pathway observed with most of the enzyme preparations tested. Among the major human P450 enzymes tested, CYP3A4 appeared to be one of the major phase I enzymes that could be responsible for the phase I metabolism of S4 [Km = 16.1 microM, Vmax = 1.6 pmol/(pmol x min)] in humans and mainly catalyzed the deacetylation, hydrolysis, and oxidation of S4. In humans, the cytosolic enzymes mainly catalyzed the hydrolysis reaction, whereas the microsomal enzymes primarily catalyzed the deacetylation reactions. Similar phase I metabolic profiles were observed in rats and dogs as well, except that the amide bond hydrolysis seemed to occur more rapidly in rats. In summary, these results showed that the major phase I reaction of S4 in human, rat, and dog is acetamide group deacetylation.
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Affiliation(s)
- Wenqing Gao
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH, USA
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