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Richter MJ, Wagmann L, Kavanagh PV, Brandt SD, Meyer MR. In vitro metabolic fate of the synthetic cannabinoid receptor agonists (quinolin-8-yl 4-methyl-3-(morpholine-4-sulfonyl)benzoate [QMMSB]) and (quinolin-8-yl 4-methyl-3-((propan-2-yl)sulfamoyl)benzoate [QMiPSB]) including isozyme mapping and carboxylesterases activity testing. Drug Test Anal 2023; 15:181-191. [PMID: 36239626 DOI: 10.1002/dta.3385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 11/09/2022]
Abstract
The synthetic cannabinoid receptor agonists (SCRAs) (quinolin-8-yl 4-methyl-3-(morpholine-4-sulfonyl)benzoate [QMMSB]) and (quinolin-8-yl 4-methyl-3-((propan-2-yl)sulfamoyl)benzoate [QMiPSB], also known as SGT-46) are based on the structure of quinolin-8-yl 4-methyl-3-(piperidine-1-sulfonyl)benzoate (QMPSB) that has been identified on seized plant material in 2011. In clinical toxicology, knowledge of the metabolic fate is important for their identification in biosamples. Therefore, the aim of this study was the identification of in vitro Phase I and II metabolites of QMMSB and QMiPSB in pooled human liver S9 fraction (pHLS9) incubations for use as screening targets. In addition, the involvement of human monooxygenases and human carboxylesterases (hCES) was examined. Analyses were performed by liquid chromatography coupled with high-resolution tandem mass spectrometry. Ester hydrolysis was found to be an important step in the Phase I metabolism of both SCRAs, with the carboxylic acid product being found only in negative ionization mode. Monohydroxy and N-dealkyl metabolites of the ester hydrolysis products were detected as well as glucuronides. CYP2C8, CYP2C9, CYP3A4, and CYP3A5 were involved in hydroxylation. Whereas enzymatic ester hydrolysis of QMiPSB was mainly catalyzed by hCES1 isoforms, nonenzymatic ester hydrolysis was also observed. The results suggest that ester hydrolysis products of QMMSB and QMiPSB and their glucuronides are suitable targets for toxicological screenings. The additional use of the negative ionization mode is recommended to increase detectability of analytes. Different cytochrome P450 (CYP) isozymes were involved in the metabolism; thus, the probability of drug-drug interactions due to CYP inhibition can be assessed as low.
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Affiliation(s)
- Matthias J Richter
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Homburg, Germany
| | - Lea Wagmann
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Homburg, Germany
| | - Pierce V Kavanagh
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St. James Hospital, Dublin 8, Ireland
| | - Simon D Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - Markus R Meyer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Homburg, Germany
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Richter MJ, Wagmann L, Brandt SD, Meyer MR. In Vitro Metabolic Fate of the Synthetic Cannabinoid Receptor Agonists 2F-QMPSB and SGT-233 Including Isozyme Mapping and Carboxylesterases Activity Testing. J Anal Toxicol 2023; 46:e198-e206. [PMID: 36083120 DOI: 10.1093/jat/bkac072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/28/2022] [Accepted: 09/07/2022] [Indexed: 01/26/2023] Open
Abstract
Quinolin-8-yl 3-(4,4-difluoropiperidine-1-sulfonyl)-4-methylbenzoate (2F-QMPSB) and 3-(4,4-difluoropiperidine-1-sulfonyl)-4-methyl-N-(2-phenylpropan-2-yl)benzamide (SGT-233) belong to a new group of synthetic cannabinoid receptor agonists containing a sulfamoyl benzoate or sulfamoyl benzamide core structure. 2F-QMPSB was identified in herbal material seized in Europe in 2018. The aims of this study were the identification of in vitro Phase I and II metabolites of 2F-QMPSB and SGT-233 to find analytical targets for toxicological screenings. Furthermore, the contribution of different monooxygenases and human carboxylesterases to Phase I metabolism was investigated. Liquid chromatography coupled to high-resolution tandem mass spectrometry was used for analysis. Ester hydrolysis was found to be an important step in the metabolism of 2F-QMPSB, which was catalyzed mainly by human carboxylesterases (hCES)1 isoforms. Additionally, nonenzymatic ester hydrolysis was observed in case of 2F-QMPSB. Notably, the carboxylic acid product derived from ester hydrolysis and metabolites thereof were only detectable in negative ionization mode. In case of SGT-233, mono- and dihydroxy metabolites were identified, as well as glucuronides. The cytochrome P450 (CYP) isozymes CYP2C8, CYP2C9, CYP2C19, CYP3A4 and CYP3A5 were found to be involved in the hydroxylation of both compounds. The results of these in vitro experiments suggest that the ester hydrolysis products of 2F-QMPSB and their glucuronides are suitable targets for toxicological screenings. In the case of SGT-233, the mono- and dihydroxy metabolites were identified as suitable screening targets. The involvement of various CYP isoforms in the metabolism of both substances reduces the likelihood of drug-drug interactions due to CYP inhibition.
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Affiliation(s)
- Matthias J Richter
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Kirrbergerstr. / Geb. 46, Homburg 66421, Germany
| | - Lea Wagmann
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Kirrbergerstr. / Geb. 46, Homburg 66421, Germany
| | - Simon D Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
| | - Markus R Meyer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Center for Molecular Signaling (PZMS), Saarland University, Kirrbergerstr. / Geb. 46, Homburg 66421, Germany
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In Vitro Metabolic Fate of the Synthetic Cannabinoid Receptor Agonists QMPSB and QMPCB (SGT-11) Including Isozyme Mapping and Esterase Activity. Metabolites 2021; 11:metabo11080509. [PMID: 34436449 PMCID: PMC8400906 DOI: 10.3390/metabo11080509] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/25/2021] [Accepted: 07/29/2021] [Indexed: 11/16/2022] Open
Abstract
Quinolin-8-yl 4-methyl-3-(piperidine-1-sulfonyl)benzoate (QMPSB) and quinolin-8-yl 4-methyl-3-(piperidine-1-carbonyl)benzoate (QMPCB, SGT-11) are synthetic cannabinoid receptor agonists (SCRAs). Knowing their metabolic fate is crucial for the identification of toxicological screening targets and to predict possible drug interactions. The presented study aimed to identify the in vitro phase I/II metabolites of QMPSB and QMPCB and to study the contribution of different monooxygenases and human carboxylesterases by using pooled human liver S9 fraction (pHLS9), recombinant human monooxygenases, three recombinant human carboxylesterases, and pooled human liver microsomes. Analyses were carried out by liquid chromatography high-resolution tandem mass spectrometry. QMPSB and QMPCB showed ester hydrolysis, and hydroxy and carboxylic acid products were detected in both cases. Mono/dihydroxy metabolites were formed, as were corresponding glucuronides and sulfates. Most of the metabolites could be detected in positive ionization mode with the exception of some QMPSB metabolites, which could only be found in negative mode. Monooxygenase activity screening revealed that CYP2B6/CYP2C8/CYP2C9/CYP2C19/CYP3A4/CYP3A5 were involved in hydroxylations. Esterase screening showed the involvement of all investigated isoforms. Additionally, extensive non-enzymatic ester hydrolysis was observed. Considering the results of the in vitro experiments, inclusion of the ester hydrolysis products and their glucuronides and monohydroxy metabolites into toxicological screening procedures is recommended.
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A Michely JA, Manier SK, Caspar AT, Brandt SD, Wallach J, Maurer HH. New Psychoactive Substances 3-Methoxyphencyclidine (3-MeO-PCP) and 3-Methoxyrolicyclidine (3-MeO-PCPy): Metabolic Fate Elucidated with Rat Urine and Human Liver Preparations and their Detectability in Urine by GC-MS, "LC-(High Resolution)-MSn" and "LC-(High Resolution)-MS/MS". Curr Neuropharmacol 2018; 15:692-712. [PMID: 27758707 PMCID: PMC5771046 DOI: 10.2174/1570159x14666161018151716] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/20/2016] [Accepted: 04/28/2016] [Indexed: 11/29/2022] Open
Abstract
Background: 3-Methoxyphencyclidine (3-MeO-PCP) and 3-methoxyrolicyclidine (3-MeO-PCPy) are two new psychoactive substances (NPS). The aims of the present study were the elucidation of their metabolic fate in rat and pooled human liver microsomes (pHLM) the identification of the cytochrome P450 (CYP) isoenzymes involved and the detectability using standard urine screening approaches (SUSA) after intake of common users’ doses using gas chromatography-mass spectrometry (GC-MS) liquid chromatography-multi-stage mass spectrometry (LC-MSn) and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS) Methods: For metabolism studies rat urine samples were treated by solid phase extraction or simple precipitation with or without previous enzymatic conjugate cleavage. After analyses via LC-HR-MSn the phase I and II metabolites were identified Results: Both drugs showed multiple aliphatic hydroxylations at the cyclohexyl ring and the heterocyclic ring single aromatic hydroxylation carboxylation after ring opening O-demethylation and glucuronidation. The transferability from rat to human was investigated by pHLM incubations where O-demethylation and hydroxylation were observed. The involvement of the individual CYP enzymes in the initial metabolic steps was investigated after single CYP incubations. For 3-MeO-PCP CYP 2B6 was responsible for aliphatic hydroxylations and CYP 2C19 and CYP 2D6 for O-demethylation. For 3-MeO-PCPy aliphatic hydroxylation was again catalyzed by CYP 2B6 and O-demethylation by CYP 2C9 and CYP 2D6 Conclusions: As only polymorphically expressed enzymes were involved pharmacogenomic variations might occur but clinical data are needed to confirm the relevance. The detectability studies showed that the authors’ SUSAs were suitable for monitoring the intake of both drugs using the identified metabolites
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Affiliation(s)
- Julian A A Michely
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg (Saar). Germany
| | - Sascha K Manier
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg (Saar). 0
| | - Achim T Caspar
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg (Saar). Germany
| | - Simon D Brandt
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg (Saar). Germany
| | - Jason Wallach
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg (Saar). Germany
| | - Hans H Maurer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg (Saar),. Germany
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Nóbrega L, Dinis-Oliveira RJ. The synthetic cathinone α-pyrrolidinovalerophenone (α-PVP): pharmacokinetic and pharmacodynamic clinical and forensic aspects. Drug Metab Rev 2018. [PMID: 29540067 DOI: 10.1080/03602532.2018.1448867] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
New psychoactive substances (NPS), often referred as 'legal highs' or 'designer drugs', are derivatives and analogs of existing psychoactive drugs that are introduced in the recreational market to circumvent existing legislation on drugs of abuse. This work aims to review the state-of-the-art regarding chemical, molecular pharmacology, and in vitro and in vivo data on toxicokinetics of the potent synthetic cathinone α-pyrrolidinovalerophenone (α-PVP or flakka or zombie drug). Chemical, pharmacological, toxicological, and clinical effects of α-PVP were searched in PubMed (U.S. National Library of Medicine) and governmental websites without limitation of the period. α-PVP is a wide spread and easy to get special type of synthetic cathinone with seemingly powerful cocaine-like stimulant effects, high brain penetration, high liability for abuse and with increased risk of adverse effects such as tachycardia, agitation, hypertension, hallucinations, delirium, mydriasis, self-injury, aggressive behavior, and suicidal ideations. α-PVP undergoes extensive metabolism via different pathways and the α-PVP itself or its metabolites β-hydroxy-α-PVP and α-PVP lactam represent the main targets for toxicological analysis in urine. There is a limited knowledge regarding the short- and long-term effects of α-PVP and metabolites, and pharmacogenetic influence, hence further clinical and forensic toxicological studies are required. Moreover, since α-PVP cannot be detected with classic routine analysis procedures, statements on the frequency of their consumption cannot be made.
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Affiliation(s)
- Leandro Nóbrega
- a Department of Public Health, Forensic Sciences, and Medical Education, Faculty of Medicine , University of Porto , Porto , Portugal
| | - Ricardo Jorge Dinis-Oliveira
- a Department of Public Health, Forensic Sciences, and Medical Education, Faculty of Medicine , University of Porto , Porto , Portugal.,b UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy , University of Porto , Porto , Portugal.,c Department of Sciences, IINFACTS - Institute of Research and Advanced Training in Health Sciences and Technologies , University Institute of Health Sciences (IUCS), CESPU, CRL , Gandra , Portugal
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Abstract
The serendipitous discovery of phencyclidine (PCP) in 1956 sets the stage for significant research efforts that resulted in a plethora of analogs and derivatives designed to explore the biological effects of this class. PCP soon became the prototypical dissociative agent that eventually sneaked through the doors of clinical laboratories and became an established street drug. Estimations suggest that around 14 PCP analogs were identified as "street drugs" in the period between the 1960s and 1990s. Fast forward to the 2000s, and largely facilitated by advancements in electronic forms of communication made possible through the Internet, a variety of new PCP analogs began to attract the attention of communities interested in the collaborative exploration of these substances. Traditionally, as was the case with the first-generation analogs identified in previous decades, the substances explored represented compounds already known in the scientific literature. As the decade of the noughties unfolded, a number of new PCP-derived substances appeared on the scene, which included some analogs that have not been previously recorded in the published literature. The aim of this chapter is to present a brief introductory overview of substances that have materialized as PCP-derived new psychoactive substances (NPS) in recent years and their known pharmacology. Since N-methyl-D-aspartate receptor (NMDAR) antagonism is implicated in mediating the subjective and mind-altering effects of many dissociative drugs, additional data are included from other analogs not presently identified as NPS.
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Affiliation(s)
- Jason Wallach
- Department of Pharmaceutical Sciences, Substance Use Disorder Institute, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, USA.
| | - Simon D Brandt
- School of Pharmacy & Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK.
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Bisetto SP, Carregaro AB, Nicolai AES, Bressan TF, Leal WP, Xavier NV, Leal DF, Andrade AFC. Hyaluronidase administered with xylazine-tiletamine-zolazepam into adipose tissue shortens recovery from anesthesia in pigs. Vet Anaesth Analg 2017; 44:594-599. [PMID: 28533108 DOI: 10.1016/j.vaa.2016.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 09/13/2016] [Accepted: 09/13/2016] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To evaluate the effect of hyaluronidase on uptake, duration and speed of elimination of xylazine-tiletamine-zolazepam administered in the subcutaneous fat over the dorsal lumbar region of swine. STUDY DESIGN Blinded, randomized, crossover study. ANIMALS Six healthy Landrace/Large White pigs weighing 132±24 kg (mean±standard deviation). METHODS Animals were administered xylazine (1 mg kg-1) and tiletamine-zolazepam (8 mg kg-1) (control treatment, CON), or xylazine-tiletamine-zolazepam at the same doses with hyaluronidase (400 IU) (treatment HYA). The treatments were administered into the dorsal lumbar adipose tissue, 2.5-3.0 cm laterally from the spinous process of the second lumbar vertebra. The latency, anesthesia and recovery periods were measured. Heart rate, noninvasive systolic, diastolic, and mean arterial pressures, respiratory rate, hemoglobin oxygen saturation and rectal temperature were recorded every 10 minutes for up to 50 minutes. RESULTS One animal in CON and one animal in HYA were responsive to stimulation and did not allow safe handling. No significant difference was found between treatments for latency (CON 11.3±5.9 minutes, HYA 7.4±5.1 minutes) and anesthesia (CON 53±53 minutes, HYA 49±38 minutes) periods. Recovery period was shorter in HYA (9±6 minutes) than in CON (32±16 minutes) (p < 0.05). Physiological variables were not significantly changed over time and were within accepted normal clinical limits for the species in both treatments. CONCLUSION AND CLINICAL RELEVANCE Hyaluronidase (400 IU) administered into adipose tissue in pigs did not reduce the latency and duration of dissociative anesthesia, but was associated with faster recovery.
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Affiliation(s)
- Shayne P Bisetto
- Department of Veterinary Science, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil
| | - Adriano B Carregaro
- Department of Veterinary Science, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil.
| | - André E S Nicolai
- Department of Veterinary Science, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil
| | - Thais F Bressan
- Department of Veterinary Science, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil
| | - William P Leal
- Department of Veterinary Science, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil
| | - Nathalia V Xavier
- Department of Veterinary Science, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil
| | - Diego F Leal
- Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, SP, Brazil
| | - André F C Andrade
- Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, SP, Brazil
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Abstract
Stereochemical factors are known to play a significant role in the metabolism of drugs and other xenobiotics. Following Prelog's lead, types of metabolic stereoselectivity can be categorized as (i) substrate stereoselectivity (the differential metabolism of two or more stereoisomeric substrates) and (ii) product stereoselectivity (the differential formation of two or more stereoisomeric metabolites from a single substrate). Combinations of the two categories exist as (iii) substrate-product stereoselectivities, meaning that product stereoselectivity itself is substrate stereoselective. Here, published examples of metabolic stereoselectivities are examined in the light of these concepts. In parallel, a graphical scheme is presented with a view to facilitate learning and help researchers to solve classification problems.
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Affiliation(s)
- Bernard Testa
- Department of Pharmacy, Lausanne University Hospital , Lausanne , Switzerland
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Sauer C, Peters FT, Haas C, Meyer MR, Fritschi G, Maurer HH. New designer drug alpha-pyrrolidinovalerophenone (PVP): studies on its metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric techniques. JOURNAL OF MASS SPECTROMETRY : JMS 2009; 44:952-964. [PMID: 19241365 DOI: 10.1002/jms.1571] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The aim of the present study was to identify the metabolites of the new designer drug alpha-pyrrolidinovalerophenone (PVP) in rat urine using GC/MS techniques. Eleven metabolites of PVP could be identified suggesting the following metabolic steps: hydroxylation of the side chain followed by dehydrogenation to the corresponding ketone; hydroxylation of the 2''-position of the pyrrolidine ring followed by dehydrogenation to the corresponding lactam or followed by ring opening to the respective aliphatic aldehyde and further oxidation to the respective carboxylic acid; degradation of the pyrrolidine ring to the corresponding primary amine; and hydroxylation of the phenyl ring, most probably in the 4'-position. The authors' screening procedure for pyrrolidinophenones allowed the detection of PVP metabolites after application of a dose corresponding to a presumed user's dose. In addition, the involvement of nine different human cytochrome P450 (CYP) isoenzymes in the side chain hydroxylation of PVP was investigated and CYP 2B6, 2C19, 2D6, and 3A4 were found to catalyze this reaction.
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Affiliation(s)
- Christoph Sauer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, D-66421 Homburg (Saar), Germany
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Sauer C, Peters FT, Staack RF, Fritschi G, Maurer HH. Metabolism and toxicological detection of a new designer drug, N-(1-phenylcyclohexyl)propanamine, in rat urine using gas chromatography–mass spectrometry. J Chromatogr A 2008; 1186:380-90. [DOI: 10.1016/j.chroma.2007.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 11/01/2007] [Accepted: 11/01/2007] [Indexed: 10/22/2022]
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Sauer C, Peters FT, Staack RF, Fritschi G, Maurer HH. New designer drugs N-(1-phenylcyclohexyl)-2-ethoxyethanamine (PCEEA) and N-(1-phenylcyclohexyl)-2-methoxyethanamine (PCMEA): Studies on their metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric techniques. JOURNAL OF MASS SPECTROMETRY : JMS 2008; 43:305-316. [PMID: 17968862 DOI: 10.1002/jms.1312] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Studies are described on the metabolism and the toxicological detection of the phencyclidine-derived designer drugs N-(1-phenylcyclohexyl)-2-ethoxyethanamine (PCEEA) and N-(1-phenylcyclohexyl)-2-methoxyethanamine (PCMEA) in rat urine using gas chromatographic/mass spectrometric (GC/MS) techniques. The identified metabolites indicated that PCEEA and PCMEA were transformed to the same metabolites by N-dealkylation and O-dealkylation partially followed by oxidation of the resulting alcohol to the respective carboxylic acid and hydroxylation of the cyclohexyl ring at different positions and combinations of those. Finally, aromatic hydroxylation of the O-dealkylated metabolites was partially followed by hydroxylation of the cyclohexyl ring at different positions. All metabolites were partially excreted in conjugated form. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction and microwave-assisted acetylation allowed the detection of an intake of a common drug users' dose both of PCEEA and PCMEA in rat urine. Assuming similar metabolism in humans, the STA should be suitable for proof of an intake of PCEEA and PCMEA in human urine, although their differentiation is not possible due to common metabolites.
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Affiliation(s)
- Christoph Sauer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, D-66421 Homburg (Saar), Germany
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12
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Kalinichev M, Robbins MJ, Hartfield EM, Maycox PR, Moore SH, Savage KM, Austin NE, Jones DNC. Comparison between intraperitoneal and subcutaneous phencyclidine administration in Sprague-Dawley rats: a locomotor activity and gene induction study. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:414-22. [PMID: 17945407 DOI: 10.1016/j.pnpbp.2007.09.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 09/07/2007] [Accepted: 09/11/2007] [Indexed: 11/27/2022]
Abstract
In a putative model of acute phencyclidine (PCP)-induced psychosis we evaluated effects of the drug on locomotor activity (LMA) and immediate early gene (IEG) induction in the rat using two routes of drug administration, intraperitoneal (i.p.) and subcutaneous (s.c.). Adult male rats received saline or PCP (1.0-5.0 mg/kg) either i.p or s.c. and were assessed for LMA for 60 min. At the end of the LMA testing animals were culled and blood and brain samples were collected for PCP concentration analysis. Separate cohorts of animals received 5.0 mg/kg PCP (i.p. or s.c.) and were used to investigate (1) the pharmacokinetics of PCP or (2) induction of IEG (Arc, c-fos, BDNF, junB, Krox-20, sgk-1, NURR1, fra-2, Krox-24, and egr-3) mRNA expression in the prefrontal cortex (PFC). Administration of PCP resulted in locomotor hyperactivity which was more robust and longer-lasting in animals dosed s.c. compared to i.p.-treated-animals. Differences in hyperlocomotion were paralleled by higher concentrations of PCP in the blood and in the brain of s.c.-treated animals compared to i.p.-treated animals. The differences in the concentration of PCP between the two routes of administration were detected 30 min after dosing and persisted for up to 4 h. Administration of PCP via the s.c. route resulted in induction of more IEGs and consistently larger magnitudes of induction than that via the i.p. route. Therefore, we have outlined the dosing conditions to induce rapid and robust effect of acute PCP on behaviour, gene induction, and pharmacokinetic profile, to allow investigation of this as a potential animal model of acute psychosis.
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Affiliation(s)
- Mikhail Kalinichev
- Biology Department, Psychiatry Centre of Excellence for Drug Discovery, GlaxoSmithKline plc, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, UK.
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Driscoll JP, Kornecki K, Wolkowski JP, Chupak L, Kalgutkar AS, O'Donnell JP. Bioactivation of Phencyclidine in Rat and Human Liver Microsomes and Recombinant P450 2B Enzymes: Evidence for the Formation of a Novel Quinone Methide Intermediate. Chem Res Toxicol 2007; 20:1488-97. [PMID: 17892269 DOI: 10.1021/tx700145k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hypothesis that the psychological side effects associated with the anesthetic phencyclidine (PCP) may be caused by irreversible binding of PCP or its reactive metabolite(s) to critical macromolecules in the brain has resulted in numerous in vitro studies aimed at characterizing pathways of PCP bioactivation. The studies described herein extend the current knowledge of PCP metabolism and provide details on a previously unknown metabolic activation pathway of PCP. Following incubations with NADPH- and GSH-supplemented human and rat liver microsomes and recombinant P450 2B enzymes, two sulfhydryl conjugates with MH+ ions at 547 and 482 Da, respectively, were detected by LC/MS/MS. Shebley et al. [(2006) Drug Metab. Dispos. 34, 375-383] have also observed the GSH conjugate 1 with MH+ at 547 Da in PCP incubations with rat P450 2B1 and rabbit P450 2B4 isoforms fortified with NADPH and GSH. The molecular weight of 1 is consistent with a bioactivation pathway involving Michael addition of the sulfhydryl nucleophile to the putative 2,3-dihydropyridinium metabolite of PCP obtained via a four-electron oxidation of the piperidine ring in the parent compound. The mass spectrum of the novel GSH adduct 2 with an MH+ ion at 482 Da was suggestive of a unique PCP bioactivation pathway involving initial ortho- or para-hydroxylation of the phenyl ring in PCP followed by spontaneous decomposition to piperidine and an electrophilic quinone methide intermediate, which upon reaction with GSH yielded adduct 2. The LC retention times and mass spectral properties of enzymatically generated 2 were identical to those of a reference standard obtained via reaction of GSH with synthetic p-hydroxyPCP in phosphate buffer (pH 7.4, 37 degrees C). 1H NMR and 13C-distortionless enhancement by polarization transfer (DEPT) NMR spectral studies on synthetically generated 2 suggested that the structural integrity of the p-hydroxyphenyl and cyclohexyl rings likely was preserved and that the site of GSH addition was the benzylic carbon joining the two scaffolds. The formation of 2 in human microsomes was reduced upon addition of the dual P450 2C19/P450 2B6 inhibitor (+)- N-3-benzylnirvanol. Consistent with this finding, both recombinant P450 2B6 and P450 2C19 catalyzed PCP bioactivation to 2. In the absence of GSH, synthetic p-hydroxyPCP underwent rapid decomposition (t1/2 approximately 5.2 min) to afford p-hydroxyphenylcyclohexanol and p-hydroxyphenylcyclohexene, presumably via the quinone methide intermediate. Overall, our findings on the facile degradation of synthetic p-hydroxyPCP to yield an electrophilic quinone methide intermediate capable of reacting with nucleophiles, including GSH and water, suggest an inherent instability of the putative phenolic PCP metabolite. Thus, if formed enzymatically in vivo, p-hydroxyPCP may not require further metabolism to liberate the quinone methide, which can then react with macromolecules. To our knowledge, this is the first report of a quinone methide reactive intermediate obtained in human-liver microsomal metabolism of PCP.
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Affiliation(s)
- James P Driscoll
- Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research and Development, Groton, CT 06340, USA
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Sauer C, Peters FT, Staack RF, Fritschi G, Maurer HH. New designer drug N-(1-phenylcyclohexyl)-3-ethoxypropanamine (PCEPA): studies on its metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric techniques. JOURNAL OF MASS SPECTROMETRY : JMS 2006; 41:1014-29. [PMID: 16817170 DOI: 10.1002/jms.1058] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Studies are described on the metabolism and toxicological detection of the phencyclidine-derived designer drug N-(1-phenylcyclohexyl)-3-ethoxypropanamine (PCEPA) in rat urine using gas chromatographic/mass spectrometric techniques. The identified metabolites indicated that PCEPA was metabolized by N-dealkylation, O-deethylation partially followed by oxidation of the resulting alcohol to the corresponding carboxylic acid, hydroxylation of the cyclohexyl ring at different positions of PCEPA, N-dealkyl PCEPA, O-deethyl PCEPA, and of the corresponding carboxylic acids. Finally, aromatic hydroxylation of PCEPA, the corresponding carboxylic acids, and O-deethyl PCEPA, the latter partially followed by oxidation to the corresponding carboxylic acid and hydroxylation of the cyclohexyl ring could be observed. All metabolites were partially excreted in the conjugated form. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction, and microwave-assisted acetylation allowed the detection in rat urine of an intake of a common drug users' dose of PCEPA. Assuming a similar metabolism in humans, the STA in human urine should be suitable as proof of intake of PCEPA.
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Affiliation(s)
- Christoph Sauer
- Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, University of Saarland, D-66421 Homburg (Saar), Germany
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Carr VM. Induced and constitutive heat shock protein expression in the olfactory system—A review, new findings, and some perspectives. ACTA ACUST UNITED AC 2006; 34:269-93. [PMID: 16841168 DOI: 10.1007/s11068-005-8358-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 11/14/2005] [Accepted: 11/15/2005] [Indexed: 12/26/2022]
Abstract
Heat shock, or stress, proteins (HSPs) are cellular proteins induced in response to conditions that cause protein denaturation, and their induction is essential for survival of such conditions. In the olfactory system we have found intense HSP expression occurs during normal processing of environmental odorants/inhalants as well as following hyperthermia and drug exposure. The HSPs involved include ubiquitin, HSP70, HSC70, and HSP25. Responses are both cell type- and stress-specific, occurring primarily in olfactory supporting cells and to some extent in Bowman's gland acinar cells. Responses to these stresses are not seen in olfactory sensory neurons. This article reviews those studies and the significance of their findings. It also discusses a distinct subpopulation of rat olfactory sensory neurons (OSNs), the 2A4(+)OSNs, found to be constitutively reactive with HSP70, the predominantly stress-inducible isoform of the 70 kD HSP family. Their high HSP70 expression appears to confer on the 2A4(+)OSNs an enhanced ability to survive damage-induced OSN turnover. New findings are also presented on HSP25-specific changes following olfactory bulbectomy. All data are discussed in the context of the overall olfactory and bioprotective functions of the olfactory mucosa.
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Affiliation(s)
- Virginia McMillan Carr
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208-3520, USA.
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16
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Jushchyshyn MI, Wahlstrom JL, Hollenberg PF, Wienkers LC. Mechanism of inactivation of human cytochrome P450 2B6 by phencyclidine. Drug Metab Dispos 2006; 34:1523-9. [PMID: 16782764 DOI: 10.1124/dmd.106.010579] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanism behind the observed inactivation of human P450 2B6 by phencyclidine (PCP) has been evaluated over the past 2 decades. The scope of the current investigation was to contribute to the fundamental knowledge of PCP oxidation and perhaps the mechanism behind P450 inactivation. To study the chemistry of PCP oxidation, we subjected PCP to the Fenton reagent. Under Fenton chemistry conditions, oxidation on all three PCP rings was observed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). When PCP was incubated with the Fenton system in the presence of glutathione (GSH), three GSH-PCP conjugates were identified. Subsequent LC-MS/MS analysis of these conjugates revealed two species that had GSH attached to the cyclohexane ring of PCP and a third conjugate in which GSH was adducted to the piperidine ring. When PCP was incubated across a panel of P450 enzymes, several enzymes, including P450s 2D6 and 3A4, were able to catalyze the formation of the PCP iminium ion, whereas P450s 2B6 and 2C19 were exclusively able to hydroxylate secondary carbons on the cyclohexane ring of PCP. Subsequent mechanistic experiments revealed that only P450s 2B6 and 2C19 demonstrated loss of catalytic activity after preincubation with 10 microM PCP. Finally, investigation of P450 2B6 inactivation using structural analogs of PCP revealed that blocking the para-carbon atom on the cyclohexane ring of PCP from oxidation protected the P450 2B6 from inactivation, which suggests that a reactive intermediate generated during the hydroxylation of the cyclohexane ring may be linked to the mechanism of inactivation of P450 2B6 by PCP.
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17
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Shebley M, Jushchyshyn MI, Hollenberg PF. SELECTIVE PATHWAYS FOR THE METABOLISM OF PHENCYCLIDINE BY CYTOCHROME P450 2B ENZYMES: IDENTIFICATION OF ELECTROPHILIC METABOLITES, GLUTATHIONE, AND N-ACETYL CYSTEINE ADDUCTS. Drug Metab Dispos 2005; 34:375-83. [PMID: 16326815 DOI: 10.1124/dmd.105.007047] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The metabolism of phencyclidine (PCP) has been studied previously in cytochrome P450 (P450)-containing microsomal systems. However, the reactive intermediate(s) that covalently binds to the P450 and leads to inactivation or leaves the active site to modify other proteins has not been identified. In this study two electrophilic intermediates of PCP were identified by mass spectrometry and by trapping with reduced glutathione (GSH) or N-acetyl cysteine (NAC). The tentative structures of these electrophilic intermediates were determined using mass spectrometry. P450s 2B1 and 2B4 formed a metabolite that exhibited an m/z of 240 corresponding to the mass of the 2,3-dihydropyridinium species of PCP or its conjugate base, the 1,2-dihydropyridine. Chemical reduction of the incubation mixture using NaBH4 resulted in the disappearance of the signal at m/z 240, consistent with reduction of a 2,3-dihydropyridinium species. Furthermore, the reactive metabolite trapped by GSH resulted in an adduct exhibiting an m/z of 547, consistent with the mass of the 2,3-dihydropyridinium species of PCP (m/z 240), that has reacted with a molecule of GSH (m/z 308). However, P450 2B6 formed a different reactive intermediate of PCP that was isolated as a GSH adduct exhibiting an m/z of 581 and an NAC adduct with an m/z of 437. Liquid chromatography-tandem mass spectrometry analysis of these adducts suggested that a di-oxygenated iminium metabolite of PCP could be the reactive intermediate formed by P450 2B6 but not by the other 2B isoforms. These data suggest that P450 2B6 favors oxidation pathways for PCP metabolism that are different from those of P450s 2B1 and 2B4.
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Affiliation(s)
- Mohamad Shebley
- Department of Pharmacology, The University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0632, USA
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18
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Zivanovic D, Stanojlovic O, Mirkovic S, Susic V. Ontogenetic study of metaphit-induced audiogenic seizures in rats. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2005; 155:42-8. [PMID: 15763274 DOI: 10.1016/j.devbrainres.2004.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Revised: 11/20/2004] [Accepted: 11/25/2004] [Indexed: 10/25/2022]
Abstract
Ontogenetic differences in susceptibility to metaphit (1-(1-(3-isothiocyanatophenyl)cyclohexyl)-piperidine)-induced audiogenic seizures were examined in young, developing (ages: 12, 18, and 25 days) and adult (90 days old) Wistar albino rats. Metaphit was injected in a dose of 10 mg/kg i.p. and animals were subjected to intense audio stimulation (100 +/- 3 dB, 60 s) at hourly intervals after administration. Audiogenic seizures (AGS) were scored according to a four point descriptive rating scale (0-3). AGS were elicited in all age groups; they were induced for 12, 15, 15, and 30 h in 12-, 18-, 25-day-old, and adult rats, respectively. Younger animals reached a peak incidence and severity of seizures before adult rats. Twenty-five-day-old rats showed greatest incidence and severity of seizures, and shortest latency. Twelve-day-old animals had longest latencies. Besides audiogenic seizures, we observed convulsions induced by metaphit only in the form of running episodes, forelimb clonus, clonic convulsions, and rearing. Results suggest that young rats develop metaphit-induced sound seizures more rapidly, but that adults have longer period of seizure susceptibility. Different susceptibility to seizures is probably due to changes in excitatory and inhibitory pathways, while maturation of blood-brain barrier is less probable, since metaphit has a lipophilic nature.
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Affiliation(s)
- Dragana Zivanovic
- Institute of Physiology, School of Medicine, University of Belgrade, Visegradska 26/II, 11000 Belgrade, Serbia.
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19
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Pesić V, Janać B, Milanović D, Tomić M, Veskov R, Rakić L. Motor effects of amphetamine in rats pretreated with either dizocilpine or phencyclidine. Behav Brain Res 2003; 147:211-5. [PMID: 14659587 DOI: 10.1016/s0166-4328(03)00142-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aim of the present study was to examine motor effects of amphetamine (AMPH) in rats pretreated with either dizocilpine (MK-801) or phencyclidine (PCP), and to estimate possible differences in these effects. Our results showed that AMPH increases the duration of motor effects of PCP, while it does not change motor effects of MK-801. These findings may reflect different mechanisms of action of MK-801 and PCP, as well as selective influence of AMPH on metabolism of these drugs.
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Affiliation(s)
- Vesna Pesić
- Laboratory of Electrophysiology and Behavior, Department of Neurobiology and Immunology, Institute for Biological Research, 29 Novembra 142, 11060 Belgrade, Yugoslavia.
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CHO ARTHURK, NARIMATSU SHIZUO, KUMAGAI YOSHITO. Metabolism of drugs of abuse by cytochromes P450. Addict Biol 1999; 4:283-301. [PMID: 20575795 DOI: 10.1080/13556219971498] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Studies of most drugs of abuse utilize in vivo animal experimentation so that the responses measured reflect the pharmacokinetics of the administered drug as well as its pharmacodynamics. These drugs are generally lipid soluble chemicals and their elimination is dependent on metabolism, so an understanding of this process is critical to the interpretation of responses. This review summarizes the interaction between drugs of abuse and cytochromes P450, the oxidative enzymes that catalyze the first step of the metabolic process. Although they process their substrates by a common chemical mechanism, these enzymes differ markedly in their regulation, i.e. induction and inhibition, their substrate selectivities, the metabolites they generate and their relative concentration in different species. The activity of an enzyme catalyzing a specific metabolic reaction can be altered by prior xenobiotic exposure, by its genetics and by a co-administered drug, so that the pharmacokinetics of the drug under study can vary with the history of the individual subject. These issues are obviously important in human studies so, when possible, the relevant human enzymes involved in the processes described have been identified.
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21
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Streeper RT, Pearson PG, Zhao Z, Mizsak SA, Sanders PE, Wienkers LC, Vrbanac JJ. In vitro metabolic transformations of 2,4-dipyrrolidinylpyrimidine: a chemical probe for P450-mediated oxidation of tirilazad mesylate. Xenobiotica 1997; 27:1131-45. [PMID: 9413917 DOI: 10.1080/004982597239895] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. We have determined that 2,4-dipyrrolidinylpyrimidine (2,4-DPP), used as a model for studies of the metabolism of therapeutic agents containing this moiety, undergoes three characteristic hydroxylations when incubated with male rat liver microsomes. Analysis of microsomal incubates of stable isotope labelled analogues of 2,4-DPP by particle beam-liquid chromatography-mass spectrometry (LC-PB-MS) has shown that the three metabolites are 4-(3-hydroxypyrrolidinyl)-2-(pyrrolidinyl)-pyrimidine (M1), 4-(2-hydroxypyrrolidinyl)-2-(pyrrolidinyl)-pyrimidine (M2) and 2-(2-hydroxypyrrolidinyl)-4-(pyrrolidinyl)-pyrimidine (M3). 2. We determined that enzymes of the cytochrome P450 family are responsible for the in vitro hydroxylations of 2,4-DPP. 3. We observed that in microsomal incubations carried out in the presence of cyanide, a single cyanide adduct is formed implicating an iminium ion intermediate in the oxidation of the 2-pyrrolidine ring. 4. We also determined the intermolecular deuterium isotope effects for the formation of each of the three products. For M1, kH/kD = 14.55 +/- 0.54; for M2, kH/kD = 6.01 +/- 0.65; and for M3, kH/kD = 5.35 +/- 1.18. 5. We interpret these data as suggesting that M2 and M3 are formed by the same mechanism, probably including the formation of an iminium ion, and that M1 is formed by direct hydrogen abstraction.
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Affiliation(s)
- R T Streeper
- Pharmacia and Upjohn, Inc., Kalamazoo, MI 49001, USA
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22
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Abstract
These studies examined the microsomal brain metabolism of phencyclidine (PCP) in male and female Sprague-Dawley rats. Several monohydroxylated metabolites of PCP were detected including cis- and trans-1-(1-phenyl-4-hydroxycyclohexyl)piperidine (c-PPC and t-PPC) and 1-(1-phenylcyclohexyl)-4-hydroxypiperidine (PCHP). The in vitro formation of these metabolites required NADPH and was inhibited by carbon monoxide. c-PPC was formed in the male and female brain microsomes at rates of 7.1 +/- 1.3 and 5.7 +/- 1.1 fmol/min per mg, respectively, while t-PPC was formed at rates of 16.2 +/- 3.3 and 16.5 +/- 4.2 fmol/min per mg. PCHP had the highest formation rate at 50.7 +/- 8.9 and 48.2 +/- 8.8 fmol/min per mg, respectively. Although previous studies with rat liver microsomes find higher levels of PCP metabolism in male rats and the formation of an irreversibly bound metabolite in male rats, the present study of brain metabolism found no sex differences in brain metabolism. The formation of PCP metabolites in male rat livers is at least partially mediated by the male-specific isozyme CYP2C11, and possibly CYP2D1. Nevertheless, the formation of the major brain metabolite, PCHP, was not inhibited by an anti-CYP2C11 or an anti-CYP2D6 antibody. However, PCHP formation was inhibited by drug inhibitors of CYP2D1-mediated metabolism, suggesting the involvement of a CYP2D isoform. These data indicate brain metabolism of PCP is significant, but unlike the liver it is not sexually dimorphic.
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Affiliation(s)
- E M Laurenzana
- College of Medicine, Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205, USA
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23
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Meng Y, Lichtman AH, Bridgen DT, Martin BR. Pharmacological potency and biodisposition of phencyclidine via inhalation exposure in mice. Drug Alcohol Depend 1996; 43:13-22. [PMID: 8957139 DOI: 10.1016/s0376-8716(96)01284-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The purpose of the present study was to characterize the pharmacological effects and biodisposition of phencyclidine (PCP) following inhalation exposure to mice. Results from these studies indicate that PCP was easily volatilized when heated in a glass pipe. Volatilization was efficient with no significant formation of pyrolytic products. Exposure to the volatilized PCP resulted in a dose-dependent impairment in motor performance in both the rotorod and inverted-screen tests. PCP was equally effective in disrupting performance on the inverted-screen and rotorod with ED50 values corresponding to the volatilization of 10.7 and 13.2 mumol, respectively. The time courses were comparable to those produced following intravenous (i.v.) administration of PCP. In order to determine the dose of drug absorbed by inhalation, mice were exposed to [3H]-PCP. The ED50 values of PCP following i.v. administration were 4.1 and 6.2 mumol/kg in the inverted screen and rotorod, respectively. The biodisposition of PCP following inhalation exposure was similar to that after i.v. injections. At doses that produced approximately 50% of the maximum motor impairment by either administration route, higher ratios of the total drug equivalents were found following i.v. injection than that after inhalation, with the brain/plasma ratios of 1.3 +/- 0.2 versus 0.58 +/- 0.02, and brain/body ratios 0.59 +/- 0.06 versus 0.35 +/- 0.1 for i.v. and inhalation, respectively. However, the brain/plasma ratios of the concentrations of PCP were similar, 1.1 versus 0.9. The body concentration of PCP equivalents that produced 50% of the maximum effect after inhalation was 4.7 +/- 0.6 mumol/kg. These results indicate that inhalation of PCP produces a similar pharmacological profile to that of i.v. administration and suggest that the drug is equipotent by these two administrations routes. Moreover, these findings are consistent with the observation that smoking is becoming the most common route of administration among drug users.
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Affiliation(s)
- Y Meng
- Department of Pharmacology and Toxicology, Medical College of Virginia/Virginia Commonwealth University, Richmond 23298-0613, USA.
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Tanaka M, Ishikawa F, Hakusui H. Isolation and identification of seven metabolites of a water-soluble platelet aggregation inhibitor in rat urine. Xenobiotica 1995; 25:1247-57. [PMID: 8592873 DOI: 10.3109/00498259509046680] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
1. Seven metabolites of 7-piperidino-1,2,3,4,5-tetrahydroimidazo[2,1- b]quinazolin-2-one dihydrochloride monohydrate (DN-9693) were isolated from rat urine by extraction with Amberlite XAD-2 and purification by silica gel and Sephadex LH-20 open-column chromatography and preparative high-performance liquid chromatography (hplc). The structure assignment of the metabolites was performed by field desorption mass spectrometry and 200-MHz Fourier transform nmr spectroscopic analysis and comparison with authentic standards when available. 2. DN-9693 underwent metabolism mainly at the piperidine ring to give the 4-hydroxypiperidine derivative (III) and 2-hydroxy-piperidine derivative, which is further metabolized to lactam (II) or delta-aminovaleric acid (V). The acyl side chain of V was shortened by beta-oxidation to form the 3-aminopropionic acid derivative (VII). V and/or VII underwent oxidative dealkylation to give the 7-amino derivative, which was conjugated with acetic acid to form the 7-acetylamino derivative (IV). DN-9693 also underwent hydrolysis of its lactam moiety to give VI. 3. The urinary excretion of III, V and VII was determined by liquid chromatography/electrochemistry (LC/EC) and V proved to be the major metabolite in rat urine. 4. A procedure is also presented for the identification of DN-9693 metabolites using LC/EC.
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Affiliation(s)
- M Tanaka
- Drug Metabolism and Analytical Chemistry Research Center, Daiichi Pharmaceutical Co. Ltd, Tokyo, Japan
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25
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Herber R, Perrin R, Ziegler JM, Villoutreix J, Minn A, Siest G. Identification of novel phencyclidine metabolites formed in vitro by rabbit microsomal metabolism. Xenobiotica 1991; 21:1493-9. [PMID: 1763523 DOI: 10.3109/00498259109044399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Phencyclidine (PCP) was incubated with rabbit liver and brain microsomal fractions, and the structures of metabolites formed by oxidation determined by g.l.c.-mass spectrometry. 2. The formation of several known mono- and di-hydroxylated metabolites, as well as two new metabolites, was seen in the liver preparations. 3. Hydroxylated PCP metabolites were also formed after incubation of PCP with brain microsomes, indicating that PCP biotransformation may occur in the brain itself.
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Affiliation(s)
- R Herber
- URA, CNRS no. 597, Centre du Médicament, Nancy, France
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26
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Sayre LM, Engelhart DA, Venkataraman B, Babu MK, McCoy GD. Generation and fate of enamines in the microsomal metabolism of cyclic tertiary amines. Biochem Biophys Res Commun 1991; 179:1368-76. [PMID: 1930182 DOI: 10.1016/0006-291x(91)91724-q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microsomal oxidation of 1-benzylpiperidine (1-BP) and its cis-2,6-dimethyl analog was studied to assess the involvement of endocyclic enamines, in equilibrium with the initially formed iminiums, in the metabolic activation of cyclic tertiary amines such as phencyclidine. Since the iminiums can be trapped with cyanide, the selective prevention by cyanide of the metabolic production of 1-benzyl-3-piperidone from 1-BP implicates the iminium in equilibrium with enamine as the source of this metabolite. In cases where iminium-enamine coupling is sterically prevented, the iminium in equilibrium with enamine species can be studied independently and are found to be more potent metabolism-dependent inactivators of cytochrome P-450 than are the corresponding parent amines. Possible mechanisms for biological oxidation of cyclic enamines to reactive intermediates are considered.
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Affiliation(s)
- L M Sayre
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106
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27
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Minn A, Ghersi-Egea JF, Perrin R, Leininger B, Siest G. Drug metabolizing enzymes in the brain and cerebral microvessels. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1991; 16:65-82. [PMID: 1907518 DOI: 10.1016/0165-0173(91)90020-9] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Several families of brain parenchyma and microvessel endothelial cell enzymes can metabolize substrates of exogenous origin. This xenobiotic metabolism includes functionalization and conjugation reactions and results in detoxication, but also possibly in the formation of pharmacologically active or neurotoxic products. The brain is partially protected from chemical insults by the physical barrier formed by the cerebral microvasculature of endothelial cells, which prevents the influx of hydrophilic molecules. These cells provide also, as a result of their drug-metabolizing enzyme activities, a metabolic barrier against penetrating lipophilic substances. The involvement of these enzymatic activities in neurotoxic events, probably responsible for neuronal dysfunctioning and/or death, neurodegenerative diseases and normal aging, is discussed.
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Affiliation(s)
- A Minn
- Centre du Médicament, U.R.A. CNRS N.597, Faculté des Sciences Pharmaceutiques et Biologiques, Université de Nancy I, France
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