1
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Muhammed Ajeebsanu M, Subhahar MB, Karakka Kal AK, Philip M, Perwad Z, Karatt TK, Graiban FM, Joseph M, Jose SV. Comprehensive metabolic investigation of dopamine reuptake inhibitor HDMP-28 in equine liver microsomes and Cunninghamella elegans for doping control. Drug Test Anal 2024. [PMID: 38225724 DOI: 10.1002/dta.3642] [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: 06/15/2023] [Revised: 09/25/2023] [Accepted: 09/30/2023] [Indexed: 01/17/2024]
Abstract
A dopamine reuptake inhibitor is a type of medication or substance that works by blocking the reuptake of dopamine in the brain. Dopamine reuptake inhibitors offer multiple effects, including increased alertness, improved mood, and therapeutic potential for conditions like depression, ADHD, and Parkinson's disease. HDMP-28, or methylnaphthidate, is a potent synthetic stimulant from the phenyltropane class. It surpasses methylphenidate in both dopamine reuptake inhibition and half-life. As a dopamine reuptake inhibitor, it boosts dopamine levels by hindering reuptake into nerve cells, resulting in heightened stimulation and increased energy. In order to comprehensively address both the tangible and potential repercussions of the unauthorized utilization of the aforementioned substance in sports, it is imperative to establish analytical methodologies for the identification of the parent drug and its primary metabolites. Additionally, a comprehensive analysis of the metabolic characteristics of HDMP-28 in both human and animal subjects has yet to be published. This study explores the metabolic conversion of HDMP-28 mediated by equine liver microsomes and Cunninghamella elegans. An extraction and detection method was developed, optimized, and validated for doping assessment in equine urine and plasma. Liquid chromatography-high-resolution mass spectrometry was employed to determine metabolite structures. The study identified 31 (22 phase I and 9 phase II) metabolites of HDMP-28, including hydroxylated, hydrogenated, and hydrolyzed analogs. Glucuronic acid-conjugated metabolites were also detected. This manuscript describes metabolites based on the in vitro studies, which might not be the same in vivo. These findings aid in the detection and understanding of the illicit use of HDMP-28 in equestrian sports.
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Affiliation(s)
| | | | | | - Moses Philip
- Equine Forensic Unit, Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | - Zubair Perwad
- Equine Forensic Unit, Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | | | - Fatma Mohammed Graiban
- Equine Forensic Unit, Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | - Marina Joseph
- Department of Bacteriology, Diagnostic Section, Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | - Shantymol V Jose
- Department of Bacteriology, Diagnostic Section, Central Veterinary Research Laboratory, Dubai, United Arab Emirates
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2
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Dabbs J, Ericson MN, Wilde JH, Lombardo RF, Ashcraft EC, Dickie DA, Harman WD. The Tungsten-Promoted Synthesis of Piperidyl-Modified erythro-Methylphenidate Derivatives. ACS CENTRAL SCIENCE 2023; 9:1775-1783. [PMID: 37780360 PMCID: PMC10540299 DOI: 10.1021/acscentsci.3c00556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Indexed: 10/03/2023]
Abstract
Due to its efficacy as a dopamine receptor agonist, methylphenidate (MPH) is of interest as a potential therapeutic for cocaine addiction. While numerous derivatives of MPH have been investigated for their potential medicinal value, functionalization of the piperidine ring has not been explored. The pyridine borane ligand in WTp(NO)(PMe3)(η2-pyBH3) is dearomatized by the metal and can be elaborated to the analogous η2-mesylpyridinium complex. Installing a methyl phenylacetate moiety at the C2' position via a Reformatsky reaction followed by a tandem protonation/nucleophilic addition sequence results in a library of erythro MPH analogues functionalized at the piperidyl C5' position. The functional group is added chemoselectively to C5', cis to the methyl phenylacetate. Repeating this procedure with an enantioenriched source of the tungsten reagent results in enantioenriched MPH derivatives. All identities of the newly reported compounds are supported by comprehensive 2D NMR and HRMS data or crystallographic data.
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Affiliation(s)
| | | | - Justin H. Wilde
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Rachel F. Lombardo
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Earl C. Ashcraft
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Diane A. Dickie
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - W. Dean Harman
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
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3
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Casiraghi A, Longhena F, Faustini G, Ribaudo G, Suigo L, Camacho-Hernandez GA, Bono F, Brembati V, Newman AH, Gianoncelli A, Straniero V, Bellucci A, Valoti E. Methylphenidate Analogues as a New Class of Potential Disease-Modifying Agents for Parkinson's Disease: Evidence from Cell Models and Alpha-Synuclein Transgenic Mice. Pharmaceutics 2022; 14:1595. [PMID: 36015221 PMCID: PMC9414221 DOI: 10.3390/pharmaceutics14081595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/20/2022] [Accepted: 07/26/2022] [Indexed: 12/02/2022] Open
Abstract
Parkinson's disease (PD) is characterized by dopaminergic nigrostriatal neurons degeneration and Lewy body pathology, mainly composed of α-synuclein (αSyn) fibrillary aggregates. We recently described that the neuronal phosphoprotein Synapsin III (Syn III) participates in αSyn pathology in PD brains and is a permissive factor for αSyn aggregation. Moreover, we reported that the gene silencing of Syn III in a human αSyn transgenic (tg) mouse model of PD at a pathological stage, manifesting marked insoluble αSyn deposits and dopaminergic striatal synaptic dysfunction, could reduce αSyn aggregates, restore synaptic functions and motor activities and exert neuroprotective effects. Interestingly, we also described that the monoamine reuptake inhibitor methylphenidate (MPH) can recover the motor activity of human αSyn tg mice through a dopamine (DA) transporter-independent mechanism, which relies on the re-establishment of the functional interaction between Syn III and α-helical αSyn. These findings support that the pathological αSyn/Syn III interaction may constitute a therapeutic target for PD. Here, we studied MPH and some of its analogues as modulators of the pathological αSyn/Syn III interaction. We identified 4-methyl derivative I-threo as a lead candidate modulating αSyn/Syn III interaction and having the ability to reduce αSyn aggregation in vitro and to restore the motility of αSyn tg mice in vivo more efficiently than MPH. Our results support that MPH derivatives may represent a novel class of αSyn clearing agents for PD therapy.
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Affiliation(s)
- Andrea Casiraghi
- Department of Pharmaceutical Sciences, University of Milan, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (A.C.); (L.S.); (E.V.)
| | - Francesca Longhena
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Gaia Faustini
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Giovanni Ribaudo
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Lorenzo Suigo
- Department of Pharmaceutical Sciences, University of Milan, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (A.C.); (L.S.); (E.V.)
| | - Gisela Andrea Camacho-Hernandez
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, NIDA-IRP, 333 Cassell Drive, Baltimore, MD 21224, USA; (G.A.C.-H.); (A.H.N.)
| | - Federica Bono
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Viviana Brembati
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, NIDA-IRP, 333 Cassell Drive, Baltimore, MD 21224, USA; (G.A.C.-H.); (A.H.N.)
| | - Alessandra Gianoncelli
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Valentina Straniero
- Department of Pharmaceutical Sciences, University of Milan, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (A.C.); (L.S.); (E.V.)
| | - Arianna Bellucci
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy; (F.L.); (G.F.); (G.R.); (F.B.); (V.B.); (A.G.); (A.B.)
| | - Ermanno Valoti
- Department of Pharmaceutical Sciences, University of Milan, Via Luigi Mangiagalli 25, 20133 Milano, Italy; (A.C.); (L.S.); (E.V.)
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4
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Papa P, Valli A, Di Tuccio M, Frison G, Zancanaro F, Buscaglia E, Locatelli CA. Analytically Confirmed Intoxication by 4-Fluoromethylphenidate, an Analog of Methylphenidate. J Anal Toxicol 2019; 43:e1-e7. [DOI: 10.1093/jat/bkz001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 12/10/2018] [Accepted: 01/09/2019] [Indexed: 11/13/2022] Open
Affiliation(s)
- Pietro Papa
- Laboratory of Clinical Chemistry, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Antonella Valli
- Laboratory of Clinical Chemistry, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Marcello Di Tuccio
- Laboratory of Clinical Chemistry, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Giampietro Frison
- Laboratory of Environmental Hygiene and Forensic Toxicology, Department of Prevention, Azienda ULSS 3 Serenissima, Mestre, Veneto, Italy
| | - Flavio Zancanaro
- Laboratory of Environmental Hygiene and Forensic Toxicology, Department of Prevention, Azienda ULSS 3 Serenissima, Mestre, Veneto, Italy
| | - Eleonora Buscaglia
- Toxicology Unit, Istituti Clinici Scientifici Maugeri SpA SB-IRCCS Pavia, Poison Control Centre and National Toxicology Information Centre, Pavia, Italy
| | - Carlo Alessandro Locatelli
- Toxicology Unit, Istituti Clinici Scientifici Maugeri SpA SB-IRCCS Pavia, Poison Control Centre and National Toxicology Information Centre, Pavia, Italy
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5
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Davidson C, Raby CAR, Barrese V, Ramsey J. In Vitro Neurochemical Assessment of Methylphenidate and Its "Legal High" Analogs 3,4-CTMP and Ethylphenidate in Rat Nucleus Accumbens and Bed Nucleus of the Stria Terminalis. Front Psychiatry 2018; 9:149. [PMID: 29892233 PMCID: PMC5985416 DOI: 10.3389/fpsyt.2018.00149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 04/03/2018] [Indexed: 12/31/2022] Open
Abstract
3,4-dichloromethylphenidate (3,4-CTMP) and ethylphenidate are new psychoactive substances and analogs of the attention deficit medication methylphenidate. Both drugs have been reported on online user fora to induce effects similar to cocaine. In the UK, 3,4-CTMP appeared on the drug market in 2013 and ethylphenidate has been sold since 2010. We aimed to explore the neurochemical effects of these drugs on brain dopamine and noradrenaline efflux. 3,4-CTMP and ethylphenidate, purchased from online vendors, were analyzed using gas chromatography and mass spectroscopy to confirm their identity. Drugs were then tested in adolescent male rat brain slices of the nucleus accumbens and stria terminalis for effects on dopamine and noradrenaline efflux respectively. Fast cyclic voltammetry was used to measure transmitter release. Methylphenidate (10 μM) increased evoked dopamine and noradrenaline efflux by 4- and 2-fold, respectively. 3,4-CTMP (0.1 and 1 μM) increased evoked dopamine and noradrenaline efflux by ~6-fold and 2-fold, respectively. Ethylphenidate (1 μM) doubled evoked dopamine and noradrenaline efflux in both cases. 3,4-CTMP's effect on dopamine efflux was greater than that of methylphenidate, but ethylphenidate appears to be a weaker dopamine transporter inhibitor. Experiments using the dopamine D2 antagonist haloperidol, the noradrenaline α2 receptor antagonist yohimbine, the dopamine transporter inhibitor GBR12909 and the noradrenaline transporter inhibitor desipramine confirmed that we were measuring dopamine in the accumbens and noradrenaline in the ventral BNST. All three psychostimulant drugs, through their effects on dopamine efflux, may have addictive liability although the effect of 3,4-CTMP on dopamine suggests that it might be most addictive and ethylphenidate least addictive.
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Affiliation(s)
- Colin Davidson
- Basic Medical Science, St George's University of London, London, United Kingdom.,Pharmacy & Biomedical Sciences, University of Central Lancashire, Preston, United Kingdom
| | | | - Vincenzo Barrese
- Basic Medical Science, St George's University of London, London, United Kingdom
| | - John Ramsey
- TICTAC Communications Ltd, St George's University of London, London, United Kingdom
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6
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Klare H, Neudörfl JM, Brandt SD, Mischler E, Meier-Giebing S, Deluweit K, Westphal F, Laussmann T. Analysis of six ‘neuro-enhancing’ phenidate analogs. Drug Test Anal 2017; 9:423-435. [DOI: 10.1002/dta.2161] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 01/04/2017] [Accepted: 01/05/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Helge Klare
- Central Customs Authority; Centre of Education and Science; Merianstrasse 110 50765 Cologne Germany
| | - Jörg M. Neudörfl
- University of Cologne; Department of Chemistry, Organic Chemistry; Greinstrasse 6 50939 Cologne Germany
| | - Simon D. Brandt
- School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Liverpool L3 3AF UK
| | - Elisabeth Mischler
- Central Customs Authority; Centre of Education and Science; Merianstrasse 110 50765 Cologne Germany
| | - Sigrid Meier-Giebing
- Central Customs Authority; Centre of Education and Science; Merianstrasse 110 50765 Cologne Germany
| | - Kathrin Deluweit
- Central Customs Authority; Centre of Education and Science; Merianstrasse 110 50765 Cologne Germany
| | - Folker Westphal
- State Bureau of Criminal Investigation Schleswig-Holstein; Section Narcotics/Toxicology; Mühlenweg 166 24116 Kiel Germany
| | - Tim Laussmann
- Central Customs Authority; Centre of Education and Science; Merianstrasse 110 50765 Cologne Germany
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7
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McLaughlin G, Morris N, Kavanagh PV, Power JD, Dowling G, Twamley B, O'Brien J, Hessman G, Murphy B, Walther D, Partilla JS, Baumann MH, Brandt SD. Analytical characterization and pharmacological evaluation of the new psychoactive substance 4-fluoromethylphenidate (4F-MPH) and differentiation between the (±)-threo and (±)-erythro diastereomers. Drug Test Anal 2017; 9:347-357. [PMID: 28103426 DOI: 10.1002/dta.2167] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Revised: 01/16/2017] [Accepted: 01/17/2017] [Indexed: 11/08/2022]
Abstract
Misuse of (±)-threo-methylphenidate (methyl-2-phenyl-2-(piperidin-2-yl)acetate; Ritalin®; MPH) has long been acknowledged, but the appearance of MPH analogs in the form of 'research chemicals' has only emerged in more recent years. 4-Fluoromethylphenidate (4F-MPH) is one of these recent examples. This study presents the identification and analytical characterization of two powdered 4F-MPH products that were obtained from an online vendor in 2015. Interestingly, the products appeared to have originated from two distinct batches given that one product consisted of (±)-threo-4F-MPH isomers whereas the second sample consisted of a mixture of (±)-threo and (±)-erythro 4F-MPH. Monoamine transporter studies using rat brain synaptosomes revealed that the biological activity of the 4F-MPH mixture resided with the (±)-threo and not the (±)-erythro isomers based on higher potencies determined for blockage of dopamine uptake (IC50 4F-MPHmixture = 66 nM vs. IC50 (±)-threo = 61 nM vs. IC50 (±)-erythro = 8,528 nM) and norepinephrine uptake (IC50 4F-MPHmixture = 45 nM vs. (±)-threo = 31 nM vs. IC50 (±)-erythro = 3,779 nM). In comparison, MPH was three times less potent than (±)-threo-4F-MPH at the dopamine transporter (IC50 = 131 nM) and around 2.5 times less potent at the norepinephrine transporter (IC50 = 83 nM). Both substances were catecholamine selective with IC50 values of 8,805 nM and >10,000 nM for (±)-threo-4F-MPH and MPH at the serotonin transporter. These findings suggest that the psychostimulant properties of (±)-threo-4F-MPH might be more potent in humans than MPH. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Gavin McLaughlin
- Department of Life and Physical Sciences, Faculty of Science and Health, Athlone Institute of Technology, Dublin Road, Athlone, Co. Westmeath, N37HD68, Ireland.,Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St James's Hospital, James's Street, Dublin 8, D08W9RT, Ireland
| | - Noreen Morris
- Department of Life and Physical Sciences, Faculty of Science and Health, Athlone Institute of Technology, Dublin Road, Athlone, Co. Westmeath, N37HD68, Ireland
| | - Pierce V Kavanagh
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St James's Hospital, James's Street, Dublin 8, D08W9RT, Ireland
| | - John D Power
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St James's Hospital, James's Street, Dublin 8, D08W9RT, Ireland.,Forensic Science Ireland, Garda HQ, Phoenix Park, Dublin 8, D08HN3X, Ireland
| | - Geraldine Dowling
- Department of Pharmacology and Therapeutics, School of Medicine, Trinity Centre for Health Sciences, St James's Hospital, James's Street, Dublin 8, D08W9RT, Ireland.,School of Chemical and Pharmaceutical Sciences, College of Sciences and Health, Dublin Institute of Technology, Kevin Street, Dublin 8, D08NF82, Ireland
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, College Green, Dublin 2, D02EV57, Ireland
| | - John O'Brien
- School of Chemistry, Trinity College Dublin, College Green, Dublin 2, D02EV57, Ireland
| | - Gary Hessman
- School of Chemistry, Trinity College Dublin, College Green, Dublin 2, D02EV57, Ireland
| | - Brian Murphy
- School of Chemical and Pharmaceutical Sciences, College of Sciences and Health, Dublin Institute of Technology, Kevin Street, Dublin 8, D08NF82, Ireland
| | - Donna Walther
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - John S Partilla
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - Michael H Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Suite 4400, Baltimore, MD, 21224, USA
| | - Simon D Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
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8
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Beharry S, Gibbons S. An overview of emerging and new psychoactive substances in the United Kingdom. Forensic Sci Int 2016; 267:25-34. [DOI: 10.1016/j.forsciint.2016.08.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 08/01/2016] [Accepted: 08/04/2016] [Indexed: 01/02/2023]
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9
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Abstract
As the first drug to see widespread use for the treatment of attention deficit hyperactivity disorder (ADHD), methylphenidate was the forerunner and catalyst to the modern era of rapidly increasing diagnosis, treatment, and medication development for this condition. During its often controversial history, it has variously elucidated the importance of dopamine signaling in memory and attention, provoked concerns about pharmaceutical cognitive enhancement, driven innovation in controlled-release technologies and enantiospecific therapeutics, and stimulated debate about the impact of pharmaceutical sales techniques on the practice of medicine. In this Review, we will illustrate the history and importance of methylphenidate to ADHD treatment and neuroscience in general, as well as provide key information about its synthesis, structure-activity relationship, pharmacological activity, metabolism, manufacturing, FDA-approved indications, and adverse effects.
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Affiliation(s)
- Cody J. Wenthur
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
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10
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Freyberg Z, Sonders MS, Aguilar JI, Hiranita T, Karam CS, Flores J, Pizzo AB, Zhang Y, Farino ZJ, Chen A, Martin CA, Kopajtic TA, Fei H, Hu G, Lin YY, Mosharov EV, McCabe BD, Freyberg R, Wimalasena K, Hsin LW, Sames D, Krantz DE, Katz JL, Sulzer D, Javitch JA. Mechanisms of amphetamine action illuminated through optical monitoring of dopamine synaptic vesicles in Drosophila brain. Nat Commun 2016; 7:10652. [PMID: 26879809 PMCID: PMC4757768 DOI: 10.1038/ncomms10652] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 01/06/2016] [Indexed: 01/04/2023] Open
Abstract
Amphetamines elevate extracellular dopamine, but the underlying mechanisms remain uncertain. Here we show in rodents that acute pharmacological inhibition of the vesicular monoamine transporter (VMAT) blocks amphetamine-induced locomotion and self-administration without impacting cocaine-induced behaviours. To study VMAT's role in mediating amphetamine action in dopamine neurons, we have used novel genetic, pharmacological and optical approaches in Drosophila melanogaster. In an ex vivo whole-brain preparation, fluorescent reporters of vesicular cargo and of vesicular pH reveal that amphetamine redistributes vesicle contents and diminishes the vesicle pH-gradient responsible for dopamine uptake and retention. This amphetamine-induced deacidification requires VMAT function and results from net H+ antiport by VMAT out of the vesicle lumen coupled to inward amphetamine transport. Amphetamine-induced vesicle deacidification also requires functional dopamine transporter (DAT) at the plasma membrane. Thus, we find that at pharmacologically relevant concentrations, amphetamines must be actively transported by DAT and VMAT in tandem to produce psychostimulant effects. Amphetamines are known to enhance extracellular dopamine levels, but the underlying mechanisms are unclear. Utilising a new pH biosensor for synaptic vesicles, the authors show that amphetamines diminish vesicle pH gradients, disrupting dopamine packaging and leading to increased neurotransmitter release.
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Affiliation(s)
- Zachary Freyberg
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA
| | - Mark S Sonders
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA.,Department of Neurology, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA
| | - Jenny I Aguilar
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA
| | - Takato Hiranita
- Psychobiology Section, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Caline S Karam
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA
| | - Jorge Flores
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA
| | - Andrea B Pizzo
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA
| | - Yuchao Zhang
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA
| | - Zachary J Farino
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA
| | - Audrey Chen
- Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, Hatos Center for Neuropharmacology, David Geffen School of Medicine University of California, Los Angeles, California 90095, USA
| | - Ciara A Martin
- UCLA Interdepartmental Program in Molecular Toxicology, University of California, Los Angeles, California 90095, USA
| | - Theresa A Kopajtic
- Psychobiology Section, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Hao Fei
- Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, Hatos Center for Neuropharmacology, David Geffen School of Medicine University of California, Los Angeles, California 90095, USA
| | - Gang Hu
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Yi-Ying Lin
- School of Pharmacy, College of Medicine, National Taiwan University, Taipei, Republic of China 10055
| | - Eugene V Mosharov
- Department of Neurology, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA
| | - Brian D McCabe
- Center for Motor Neuron Biology and Disease, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Department of Pathology and Cell Biology, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Department of Neuroscience, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA
| | - Robin Freyberg
- Department of Psychology, Stern College for Women, Yeshiva University, New York, New York 10016, USA
| | | | - Ling-Wei Hsin
- School of Pharmacy, College of Medicine, National Taiwan University, Taipei, Republic of China 10055
| | - Dalibor Sames
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - David E Krantz
- Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, Hatos Center for Neuropharmacology, David Geffen School of Medicine University of California, Los Angeles, California 90095, USA
| | - Jonathan L Katz
- Psychobiology Section, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - David Sulzer
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA.,Department of Neurology, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Department of Pharmacology, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA
| | - Jonathan A Javitch
- Department of Psychiatry, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York 10032, USA.,Department of Pharmacology, College of Physicians &Surgeons, Columbia University, New York, New York 10032, USA
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11
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Influence of sensitization on the discriminative stimulus effects of methylphenidate in mice. Behav Pharmacol 2015; 25:766-74. [PMID: 25325285 DOI: 10.1097/fbp.0000000000000095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Methylphenidate (MPH) remains an important therapy for attention-deficit hyperactivity disorder, but aspects of its pharmacology remain unclear. In the present study, we used a regimen of MPH (8 mg/kg daily×14 days) in C57BL/6J mice to determine whether establishing locomotor sensitization to MPH influenced the acquisition and the dose-response function of MPH in a classic drug discrimination procedure. MPH-sensitized mice (SENS group) showed enhanced locomotor activity to the 8 mg/kg exposure dose as well as a 2 mg/kg dose before discrimination training. However, the SENS mice did not acquire discrimination of either a low dose (2 mg/kg) or a higher dose (4 mg/kg) of MPH any more rapidly than the CTRL mice. Further, during generalization testing, the dose-response functions for the SENS and CTRL mice were identical. Therefore, we did not find that previous exposure to MPH, which produced a sensitized locomotor response, facilitated MPH discrimination.
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12
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Heal DJ, Gosden J, Smith SL. Dopamine reuptake transporter (DAT) "inverse agonism"--a novel hypothesis to explain the enigmatic pharmacology of cocaine. Neuropharmacology 2014; 87:19-40. [PMID: 24953830 DOI: 10.1016/j.neuropharm.2014.06.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/07/2014] [Accepted: 06/09/2014] [Indexed: 12/20/2022]
Abstract
The long held view is cocaine's pharmacological effects are mediated by monoamine reuptake inhibition. However, drugs with rapid brain penetration like sibutramine, bupropion, mazindol and tesofensine, which are equal to or more potent than cocaine as dopamine reuptake inhibitors, produce no discernable subjective effects such as drug "highs" or euphoria in drug-experienced human volunteers. Moreover they are dysphoric and aversive when given at high doses. In vivo experiments in animals demonstrate that cocaine's monoaminergic pharmacology is profoundly different from that of other prescribed monoamine reuptake inhibitors, with the exception of methylphenidate. These findings led us to conclude that the highly unusual stimulant profile of cocaine and related compounds, eg methylphenidate, is not mediated by monoamine reuptake inhibition alone. We describe the experimental findings which suggest cocaine serves as a negative allosteric modulator to alter the function of the dopamine reuptake transporter (DAT) and reverse its direction of transport. This results in a firing-dependent, retro-transport of dopamine into the synaptic cleft. The proposed mechanism of cocaine is, therefore, different from other small molecule negative allostereric modulators of the monoamine reuptake transporters, eg SoRI-6238, which merely reduce the rate of inward transport. Because the physiological role of DAT is to remove dopamine from the synapse and the action of cocaine is the opposite of this, we have postulated that cocaine's effect is analogous to an inverse agonist. If this hypothesis is validated then cocaine is the prototypical compound that exemplifies a new class of monoaminergic drugs; DAT "inverse agonists". This article is part of the Special Issue entitled 'CNS Stimulants'.
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Affiliation(s)
- David J Heal
- RenaSci Limited, BioCity, Pennyfoot Street, Nottingham NG1 1GF, UK.
| | - Jane Gosden
- RenaSci Limited, BioCity, Pennyfoot Street, Nottingham NG1 1GF, UK
| | - Sharon L Smith
- RenaSci Limited, BioCity, Pennyfoot Street, Nottingham NG1 1GF, UK.
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Uchiyama N, Matsuda S, Kawamura M, Shimokawa Y, Kikura-Hanajiri R, Aritake K, Urade Y, Goda Y. Characterization of four new designer drugs, 5-chloro-NNEI, NNEI indazole analog, α-PHPP and α-POP, with 11 newly distributed designer drugs in illegal products. Forensic Sci Int 2014; 243:1-13. [PMID: 24769262 DOI: 10.1016/j.forsciint.2014.03.013] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 02/09/2014] [Accepted: 03/12/2014] [Indexed: 11/24/2022]
Abstract
Our continuous survey of illegal products in Japan revealed the new distribution of 15 designer drugs. We identified four synthetic cannabinoids, i.e., NNEI (1), 5-fluoro-NNEI (2), 5-chloro-NNEI (3) and NNEI indazole analog (4), and seven cathinone derivatives, i.e., MPHP (5), α-PHPP (6), α-POP (7), 3,4-dimethoxy-α-PVP (8), 4-fluoro-α-PVP (9), α-ethylaminopentiophenone (10) and N-ethyl-4-methylpentedrone (11). We also determined LY-2183240 (12) and its 2'-isomer (13), which were reported to inhibit endocannabinoid uptake, a methylphenidate analog, 3,4-dichloromethylphenidate (14), and an MDA analog, 5-APDB (15). No chemical and pharmaceutical data for compounds 3, 4, 6 and 7 had been reported, making this the first report on these compounds.
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Affiliation(s)
- Nahoko Uchiyama
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
| | - Satoru Matsuda
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Maiko Kawamura
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Yoshihiko Shimokawa
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Ruri Kikura-Hanajiri
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Kosuke Aritake
- Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita-City, Osaka 565-0874, Japan
| | - Yoshihiro Urade
- Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita-City, Osaka 565-0874, Japan
| | - Yukihiro Goda
- National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
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14
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Salek RL, Claussen CM, Pérez A, Dafny N. Acute and chronic methylphenidate alters prefrontal cortex neuronal activity recorded from freely behaving rats. Eur J Pharmacol 2012; 679:60-7. [PMID: 22306242 DOI: 10.1016/j.ejphar.2012.01.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 01/03/2012] [Accepted: 01/13/2012] [Indexed: 01/01/2023]
Abstract
Today's students around the world are striking deals to buy and sell the drug methylphenidate (MPD) for cognitive enhancement. Our knowledge on the effects of MPD on the brain is very limited. The present study was designed to investigate the acute and chronic effect of MPD on the prefrontal cortex (PFC) neurons. On experimental day 1 (ED1) recordings were obtained following saline injections and after 2.5 mg/kg MPD. On ED2 through ED6, daily single 2.5 mg/kg MPD was given followed by 3 washout days (ED7 to 9). On ED10, neuronal recordings were resumed from the same animal after saline and MPD injection similar to that obtained at ED1. Ninety PFC units were recorded, all responded to the initial MPD injection, 66 units (73%) increased their activity at ED10. Recordings were resumed for the 66 units that increased their firing rate at ED1, and following MPD injection 54 units (82%) exhibited significant increases in their baseline firing rates compared to ED1 baseline. When these 54 units were rechallenged (chronic effect) with MPD, 39/54 (72%) exhibited reduction in their firing rate which can be interpreted as tolerance. From the 24 (27%) units that responded to MPD at ED1 by decreasing their activity, 14 units (58%) exhibited a decrease in their baseline firing rates at ED10 compared to ED1 baseline. However, following MPD rechallenge of these 14 units, 11 units (79%) exhibited an increase in their firing rate which is interpreted as sensitization. In conclusion, all PFC units modified their neural baseline activity.
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Affiliation(s)
- R Layla Salek
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, 6431 Fannin Street, suite 7.208B, Houston, TX 77225, United States
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15
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Abstract
Methylphenidate (MPH) therapy for attention-deficit/hyperactivity disorder is common in children and adults. Concerns regarding abuse of MPH prompted studies to better understand its pharmacology. We used an established drug discrimination task to determine whether MPH could be discriminated by C57BL/6J (B6) mice. B6 mice learned to discriminate cues produced by racemic MPH (dl-MPH 5.0 mg/kg) or half the dose of pure d-isomer (2.5 mg/kg), and dose-response tests established appropriate reductions in discrimination with declining dose. Importantly, the two drug forms generalized to each other completely in substitution tests; consistent with reports that the l-isomer is pharmacodynamically inactive. An additional experiment indicated that lower doses (1 and 2 mg/kg) of dl-MPH did not support acquisition of MPH discrimination despite extensive training. Mice acquired discrimination of dl-MPH only when the dose was increased to 4 mg/kg. Thus, although these lower doses increased drug lever responding in mice trained on the higher dose, their stimuli were not sufficient to support acquisition of the discrimination task. These findings correspond to earlier studies conducted in our laboratory on threshold doses needed to produce stimulatory effects of motor activity in B6 mice. These preclinical findings provide insight into the relative potency, and by extension, efficacy of dl-MPH versus d-MPH doses.
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Abstract
The concept of using stimulants to treat cocaine and methamphetamine dependence is largely based on the "replacement" therapy model that has shown efficacy for treating nicotine and opiate dependence. Although results have been mixed, some evidence supports using stimulant medication to reduce cocaine use. There are not enough data to date to determine the efficacy of stimulants for methamphetamine dependence. Drawbacks of stimulants as treatments include the potential for abuse of the treatment, which necessitates careful screening and monitoring of patients. Possible reasons for efficacy of stimulants include enhancement of monoamine function dysregulated by chronic cocaine or methamphetamine use. Newer medications that enhance dopamine function but lack the abuse potential of older stimulants are being studied. It is hoped that these medications will provide safe, effective treatment for cocaine and methamphetamine dependence, but more research on this topic is needed.
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Affiliation(s)
- F Gerard Moeller
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston, 1300 Moursund, Houston, TX 77030, USA.
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17
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Differential pharmacokinetics and pharmacodynamics of methylphenidate enantiomers: does chirality matter? J Clin Psychopharmacol 2008; 28:S54-61. [PMID: 18480678 DOI: 10.1097/jcp.0b013e3181733560] [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] [Indexed: 10/22/2022]
Abstract
d,l-threo-methylphenidate (MPH) is an effective first-line treatment for the symptoms associated with attention-deficit/hyperactivity disorder. threo-methylphenidate inhibits the dopamine transporter and the norepinephrine transporter, resulting in elevations of these monoamines after impulse release. Although MPH has long been administered as a racemic mixture of the 2 enantiomers, d-MPH and l-MPH, converging lines of evidence drawn from investigations using in vitro systems, animal models, and humans indicate that it is predominantly, if not exclusively, d-MPH that mediates the pharmacological/therapeutic actions of MPH. In both rodent and primate animal models, the binding of radiolabeled d-MPH to dopamine transporter was found to be selective, saturable, and reversible, whereas binding of l-MPH was diffuse and nonspecific. The behavioral effects of the enantiomers of MPH have been tested in several animal models, and results indicate these observed behavioral changes are likewise mediated by d-MPH, whereas l-MPH has little or no effect.The contribution of the l-isomer to the overall pharmacological profile of the racemate remains unclear, owing to several studies suggesting that l-MPH may not be merely an inert isomeric ballast. For example, behavioral studies conducted in rats demonstrate an attenuation of the effect of d-MPH in animals pretreated with l-MPH, suggesting that l-MPH may interfere with the action of the active enantiomer. The importance of MPH chirality to central nervous system MPH receptor targeting has culminated in human imaging studies revealing that d-MPH binds specifically to striatal structures, whereas l-MPH binding is nonspecific. Taken together, data from in vitro, animal, and human studies support the premise that the d-enantiomer of MPH mediates the neurophysiological actions of MPH and therefore likely mediates its clinical efficacy.
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18
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Kim DI, Deutsch HM, Ye X, Schweri MM. Synthesis and pharmacology of site-specific cocaine abuse treatment agents: restricted rotation analogues of methylphenidate. J Med Chem 2007; 50:2718-31. [PMID: 17489581 DOI: 10.1021/jm061354p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of threo-1-aza-3 or 4-substituted-5-phenyl[4.4.0]decanes (quinolizidines), which were envisioned as restricted rotational analogues (RRAs) of methylphenidate (MP), was synthesized and tested for inhibitory potency against [(3)H]WIN35,428, [3H]citalopram, and [3H]nisoxetine binding to the dopamine, serotonin, and norepinephrine transporters, respectively. Two different synthetic schemes were used; a Wittig reaction or acylation (followed by an intramolecular condensation) was a key feature of each scheme. The unsubstituted RRA, threo(trans)-1-aza-5-phenyl[4.4.0]decane (12a), was equipotent to unconstrained threo-MP against [(3)H]WIN35,428 binding. The extra ring in these RRAs (which reduces the conformational freedom) and the orientation and polarity of substituents at the 4-position on this extra ring are of critical importance to the biological activity. Generally, the RRAs paralleled the corresponding unconstrained MP derivatives in binding affinity to the three transporters. The results suggest that the conformation of MP in which the carbonyl group of the methyl ester is H-bonded to the piperidinyl N-H may be the bioactive form of the molecule.
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Affiliation(s)
- Deog-Il Kim
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
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19
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Heal DJ, Pierce DM. Methylphenidate and its isomers: their role in the treatment of attention-deficit hyperactivity disorder using a transdermal delivery system. CNS Drugs 2006; 20:713-38. [PMID: 16953648 DOI: 10.2165/00023210-200620090-00002] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
dl-threo-Methylphenidate is a highly efficacious drug for treating attention-deficit hyperactivity disorder (ADHD) that is currently administered as immediate- or controlled-release and osmotically controlled-released formulations. The drug exists as two enantiomers, d-threo-methylphenidate and l-threo-methylphenidate, with the former having been developed as a medication to treat ADHD in its own right. dl-threo-Methylphenidate undergoes enantioselective metabolism in the liver, which results in marked differences in the plasma concentrations of its isomers, depending on the route of administration and formulation. When dl-threo-methylphenidate is orally administered, the plasma concentrations of d-threo-methylphenidate are higher than those of l-threo-methylphenidate. However, with the recently developed methylphenidate transdermal system (MTS), 'first-pass' metabolism is circumvented and, as a consequence, plasma concentrations of d-threo-methylphenidate are consistent with those produced by oral formulations, but the relative concentrations of l-threo-methylphenidate are much higher, i.e. 50-60% of those of d-threo-methylphenidate. In this article, we review the pharmacokinetics and pharmacology of dl-threo-methylphenidate and its isomers to assess the extent to which their mechanism of action as noradrenaline (norepinephrine) and dopamine reuptake inhibitors is responsible for their efficacy and commonly occurring adverse effects. The major findings are that d-threo-methylphenidate and l-threo-methylphenidate share the same pharmacological profile as the parent racemate, i.e. catecholamine-selective reuptake inhibition with higher potency against dopamine versus noradrenaline reuptake in vivo. However, d-threo-methylphenidate is approximately 10-fold more potent than the l-isomer in this regard. For these drugs, their abilities not only to ameliorate the behavioural and cognitive dysfunctions in ADHD, but also to induce the common adverse effects of reduced appetite, nausea/vomiting and stomach ache, are almost certainly due to their ability to potentiate noradrenergic and/or dopaminergic function in the central and peripheral nervous systems. The sympathomimetic actions of ADHD drugs on cardiovascular function are currently an issue of concern. Since noradrenaline reuptake inhibition is the likely mediator for the effects of dl-threo-methylphenidate on blood pressure and heart rate, the more potent d-isomer will therefore be predominantly responsible. Motor and vocal tics are the other important adverse event to be considered in the treatment of ADHD. It is now accepted that tics are a frequently occurring behavioural manifestation of ADHD itself and the evidence for or against their exacerbation by treatment with dl-threo-methylphenidate or other stimulants remains highly contradictory. Focusing on the enantiomers of dl-threo-methylphenidate, it can be concluded that d-threo-methylphenidate, which is the more potent and abundant of the two isomers, is the major contributor of both efficacy and adverse effects, irrespective of the formulation or route of administration of the racemate. Moreover, for the oral, extended-release formulations of dl-threo-methylphenidate, the d-isomer represents the only pharmacologically active moiety when these medications are used in the clinic. With the MTS, plasma concentrations of l-threo-methylphenidate are higher than are achieved using oral formulations, but even in this case, it is likely that the contribution of this enantiomer to the efficacy and adverse effects of the racemate is no greater than 5-10% of the total.
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Affiliation(s)
- David J Heal
- RenaSci Consultancy Ltd, BioCity, Nottingham, UK.
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20
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Jain R, Holtzman SG. Caffeine induces differential cross tolerance to the amphetamine-like discriminative stimulus effects of dopaminergic agonists. Brain Res Bull 2005; 65:415-21. [PMID: 15833596 DOI: 10.1016/j.brainresbull.2005.02.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Accepted: 02/15/2005] [Indexed: 01/01/2023]
Abstract
The purpose of this study was to determine if caffeine induces cross tolerance to the amphetamine-like discriminative stimulus effects of dopaminergic drugs that act through distinct mechanisms (e.g., release, uptake inhibition, direct activation of dopamine D(1)- or D(2)-family receptors). Rats were trained to discriminate 1.0 mg/kg d-amphetamine from saline in a two-choice discrete-trial procedure. Stimulus-generalization curves were generated by cumulative dosing for d-amphetamine (0.1-1.0 mg/kg), methylphenidate (0.3-5.6 mg/kg), SKF 81297 (0.3-3.0 mg/kg), and R-(-)-propylnorapomorphine (NPA; 0.001-1.78 mg/kg), as well as for caffeine (3.0-56 mg/kg); curves were re-determined after twice daily injections of caffeine (30 mg/kg) for 3.5 days. The rats generalized dose dependently to the four dopaminergic drugs, but only to a limited extent to caffeine. Twice daily injections of caffeine induced significant cross tolerance (i.e., increased ED(50)) to the amphetamine-like discriminative effects of methylphenidate and SKF 81297, attenuated non-significantly the effects of NPA, and did not alter the effects of amphetamine. Thus, caffeine produces differential cross tolerance to the amphetamine-like discriminative effects of dopaminergic drugs, a phenomenon in which the dopamine D(1) receptor appears to have an important role.
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Affiliation(s)
- Raka Jain
- National Drug Dependence Treatment Centre, Department of Psychiatry, All India Institute of Medical Sciences, New Delhi-110029, India.
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21
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Gilbert KM, Skawinski WJ, Misra M, Paris KA, Naik NH, Buono RA, Deutsch HM, Venanzi CA. Conformational analysis of methylphenidate: comparison of molecular orbital and molecular mechanics methods. J Comput Aided Mol Des 2005; 18:719-38. [PMID: 15865064 DOI: 10.1007/s10822-004-7610-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methylphenidate (MP) binds to the cocaine binding site on the dopamine transporter and inhibits reuptake of dopamine, but does not appear to have the same abuse potential as cocaine. This study, part of a comprehensive effort to identify a drug treatment for cocaine abuse, investigates the effect of choice of calculation technique and of solvent model on the conformational potential energy surface (PES) of MP and a rigid methylphenidate (RMP) analogue which exhibits the same dopamine transporter binding affinity as MP. Conformational analysis was carried out by the AM1 and AM1/SM5.4 semiempirical molecular orbital methods, a molecular mechanics method (Tripos force field with the dielectric set equal to that of vacuum or water) and the HF/6-31G* molecular orbital method in vacuum phase. Although all three methods differ somewhat in the local details of the PES, the general trends are the same for neutral and protonated MP. In vacuum phase, protonation has a distinctive effect in decreasing the regions of space available to the local conformational minima. Solvent has little effect on the PES of the neutral molecule and tends to stabilize the protonated species. The random search (RS) conformational analysis technique using the Tripos force field was found to be capable of locating the minima found by the molecular orbital methods using systematic grid search. This suggests that the RS/Tripos force field/vacuum phase protocol is a reasonable choice for locating the local minima of MP. However, the Tripos force field gave significantly larger phenyl ring rotational barriers than the molecular orbital methods for MP and RMP. For both the neutral and protonated cases, all three methods found the phenyl ring rotational barriers for the RMP conformers/invertamers (denoted as cte, tte, and cta) to be: cte, tte > MP > cta. Solvation has negligible effect on the phenyl ring rotational barrier of RMP. The B3LYP/6-31G* density functional method was used to calculate the phenyl ring rotational barrier for neutral MP and gave results very similar to those of the HF/6-31G* method.
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Affiliation(s)
- Kathleen M Gilbert
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, 323 King Blvd., Newark, NJ 07102, USA
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22
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Volz TJ, Bjorklund NL, Schenk JO. Methylphenidate analogs with behavioral differences interact differently with arginine residues on the dopamine transporter in rat striatum. Synapse 2005; 57:175-8. [PMID: 15945061 DOI: 10.1002/syn.20161] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The methylphenidate analogs N-methyl-4-methyl-methylphenidate and N-benzylmethylphenidate are believed to interact differently with the dopamine transporter (DAT) in vitro and in vivo. Herein, we report that methylphenidate and N-methyl-4-methyl-methylphenidate, but not N-benzylmethylphenidate, protect the rat striatal DAT from the arginine-selective chemical modifying agent, phenylglyoxal. This suggests that methylphenidate and N-methyl-4-methyl-methylphenidate, but not N-benzylmethylphenidate, interact with the guanidine groups of arginine residues in the DAT of rat striatum. This differential interaction may, at least in part, explain the in vitro and in vivo differences between N-methyl-4-methyl-methylphenidate and N-benzylmethylphenidate.
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Affiliation(s)
- Trent J Volz
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA
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23
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Abstract
Cocaine abuse is a serious health problem in many areas of the world, yet there are no proven effective medications for the treatment of cocaine dependence. Preclinical studies suggest that the reinforcing effect of cocaine that promotes its abuse is mediated by blockade of the presynaptic dopamine transporter. This results in increased dopamine activity in the mesolimbic or meso-accumbens dopamine reward system of brain. Development of new medications to treat cocaine dependence has focused on manipulation of this dopamine system, either by direct action on dopamine binding sites (transporter or receptors) or indirectly by affecting other neurotransmitter systems that modulate the dopamine system. In principle, a medication could act via one of three mechanisms: (i) as a substitute for cocaine by producing similar dopamine effects; (ii) as a cocaine antagonist by blocking the binding of cocaine to the dopamine transporter; or (iii) as a modulator of cocaine effects by acting at other than the cocaine binding site. The US National Institute on Drug Abuse has a Clinical Research Efficacy Screening Trial (CREST) programme to rapidly screen existing medications. CREST identified four medications warranting phase II controlled clinical trials: cabergoline, reserpine, sertraline and tiagabine. In addition, disulfiram and selegiline (deprenyl) have been effective and well tolerated in phase II trials. However, selegiline was found ineffective in a recent phase III trial. Promising existing medications probably act via the first or third aforementioned mechanisms. Sustained-release formulations of stimulants such as methylphenidate and amfetamine (amphetamine) have shown promise in a stimulant substitution approach. Disulfiram and selegiline increase brain dopamine concentrations by inhibition of dopamine-catabolising enzymes (dopamine-beta-hydroxylase and monoamine oxidase B, respectively). Cabergoline is a direct dopamine receptor agonist, while reserpine depletes presynaptic stores of dopamine (as well as norepinephrine and serotonin). Sertraline, baclofen and vigabatrin indirectly reduce dopamine activity by increasing activity of neurotransmitters (serotonin and GABA) that inhibit dopamine activity. Promising new medications act via the second or third aforementioned mechanisms. Vanoxerine is a long-acting inhibitor of the dopamine transporter which blocks cocaine binding and reduces cocaine self-administration in animals. Two dopamine receptor ligands that reduce cocaine self-administration in animals are also undergoing phase I human safety trials. Adrogolide is a selective dopamine D(1) receptor agonist; BP 897 is a D(3) receptor partial agonist.A pharmacokinetic approach to treatment would block the entry of cocaine into the brain or enhance its catabolism so that less cocaine reached its site of action. This is being explored in animals using the natural cocaine-metabolising enzyme butyrylcholinesterase (or recombinant versions with enhanced capabilities), catalytic antibodies, and passive or active immunisation to produce anti-cocaine binding antibodies. A recent phase I trial of a "cocaine vaccine" found it to be well tolerated and producing detectable levels of anti-cocaine antibodies for up to 9 months after immunisation.
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Affiliation(s)
- David A Gorelick
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Department of Health and Human Services, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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24
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Dutta AK, Zhang S, Kolhatkar R, Reith MEA. Dopamine transporter as target for drug development of cocaine dependence medications. Eur J Pharmacol 2003; 479:93-106. [PMID: 14612141 DOI: 10.1016/j.ejphar.2003.08.060] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Because much evidence implicates the dopamine transporter in the reinforcing effects of cocaine, development of potential medications for cocaine dependence has included the dopamine transporter as a target. The present overview covers progress in the drug development area regarding several classes of dopamine uptake inhibitors, with an emphasis on structure-activity relationships that enhance potency and selectivity at transporters for dopamine compared with those for serotonin or norepinephrine. The following categories of compounds are covered: tropane, benztropine, 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR), methylphenidate, mazindol, and phencyclidine analogs. Activity at transporters as well as on behavior is highlighted.
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Affiliation(s)
- Aloke K Dutta
- Department of Pharmaceutical Sciences, Applebaum College of Pharmacy and Health Science, Wayne State University, 3128 Applebaun Hall, Detroit, MI 48202, USA.
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25
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Kim DI, Schweri MM, Deutsch HM. Synthesis and pharmacology of site specific cocaine abuse treatment agents: 8-substituted isotropane (3-azabicyclo[3.2.1]octane) dopamine uptake inhibitors. J Med Chem 2003; 46:1456-64. [PMID: 12672245 DOI: 10.1021/jm020410t] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of 8-substituted-3-azabicyclo[3.2.1]octanes (isotropanes) were synthesized and tested for inhibitor potency using [(3)H]WIN 35,428 binding at the dopamine (DA) transporter, [(3)H]citalopram binding at the serotonin (5-HT) transporter, and [(3)H]DA uptake assays. The synthesis started with a Mannich condensation of cyclopentanone, benzylamine, and fomaldehyde to afford N-benzyl-3-azabicyclo[3.2.1]octan-8-one (6). The 8-phenyl group was introduced by Grignard addition to ketone 6 or nucleophilic displacement via a triflate of the corresponding alcohol 7a. The 8beta-phenyl-8alpha-alcohols from Grignard addition generally have low affinity for the two transporters and do not effectively inhibit the uptake of [(3)H]DA. The 8beta-phenyl compound (14) without the hydroxyl group at C-8 was much more potent (22-fold) for [(3)H]WIN 35,428 binding inhibition than the corresponding 8beta-phenyl-8alpha-hydroxy compound (7a). The 8alpha-phenyl compound 8a was almost as potent as cocaine in binding to the DA transporter (IC(50) = 234 nM vs 159 nM for cocaine), whereas the C-8 epimer, compound 14, was somewhat less potent (IC(50) = 785 nM). The lower potency of 14 (beta-orientation of 8-phenyl group) as compared to 8a (alpha-orientation) was unexpected, based on modeling studies comparing the new compounds to WIN 35,065-2, an analogue of cocaine. The benzhydryl ethers at C-8 (17), analogous to the benztropines, had better selectivity than the corresponding phenyl compounds, 8a and 14, for the DA transporter as compared to the 5-HT transporter. The isotropane and benzisotropine analogues seem to bind in a manner that is more similar to that of the benztropine compounds 5 rather than those of cocaine and WIN 35,065-2.
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Affiliation(s)
- Deog-Il Kim
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332-0400, USA
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