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Lee KH, Won SJ, Oyinloye P, Shi L. Unlocking the Potential of High-Quality Dopamine Transporter Pharmacological Data: Advancing Robust Machine Learning-Based QSAR Modeling. bioRxiv 2024:2024.03.06.583803. [PMID: 38558976 PMCID: PMC10979915 DOI: 10.1101/2024.03.06.583803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The dopamine transporter (DAT) plays a critical role in the central nervous system and has been implicated in numerous psychiatric disorders. The ligand-based approaches are instrumental to decipher the structure-activity relationship (SAR) of DAT ligands, especially the quantitative SAR (QSAR) modeling. By gathering and analyzing data from literature and databases, we systematically assemble a diverse range of ligands binding to DAT, aiming to discern the general features of DAT ligands and uncover the chemical space for potential novel DAT ligand scaffolds. The aggregation of DAT pharmacological activity data, particularly from databases like ChEMBL, provides a foundation for constructing robust QSAR models. The compilation and meticulous filtering of these data, establishing high-quality training datasets with specific divisions of pharmacological assays and data types, along with the application of QSAR modeling, prove to be a promising strategy for navigating the pertinent chemical space. Through a systematic comparison of DAT QSAR models using training datasets from various ChEMBL releases, we underscore the positive impact of enhanced data set quality and increased data set size on the predictive power of DAT QSAR models.
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Affiliation(s)
- Kuo Hao Lee
- Computational Chemistry and Molecular Biophysics Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse – Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Sung Joon Won
- Computational Chemistry and Molecular Biophysics Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse – Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Precious Oyinloye
- Computational Chemistry and Molecular Biophysics Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse – Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse – Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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Jaeschke RR, Sujkowska E, Sowa-Kućma M. Methylphenidate for attention-deficit/hyperactivity disorder in adults: a narrative review. Psychopharmacology (Berl) 2021; 238:2667-2691. [PMID: 34436651 PMCID: PMC8455398 DOI: 10.1007/s00213-021-05946-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 07/31/2021] [Indexed: 12/12/2022]
Abstract
RATIONALE Psychostimulants, including methylphenidate (MPH), are the mainstay of pharmacotherapy for attention-deficit/hyperactivity disorder (ADHD) in adults. Even though MPH is the most commonly used medication for ADHD these days, there are relatively few resources available that provide comprehensive insight into the pharmacological and clinical features of the compound. OBJECTIVE The aim of this paper is to provide an up-to-date outline of the pharmacology and clinical utility of MPH for ADHD in adult patients. METHODS While conducting the narrative review, we applied structured search strategies covering the two major online databases (MEDLINE and Cochrane Central Register of Controlled Trials). In addition, we performed handsearching of reference lists of relevant papers. RESULTS Methylphenidate exhibits multimodal mechanism of action, working primarily as a dopamine and noradrenaline reuptake inhibitor. It also protects the dopaminergic system against the ongoing 'wearing off' (by securing a substantial reserve pool of the neurotransmitter, stored in the presynaptic vesicles). In placebo-controlled trials, MPH was shown to be moderately effective both against the core ADHD symptoms (standardized mean difference [SMD], 0.49; 95% confidence interval [CI], 0.35-0.64), and the accompanying emotion regulation deficits (SMD, 0.34; 95% CI, 0.23-0.45). The most common adverse events related to long-term treatment with MPH are decreased appetite (~ 20%), dry mouth (15%), heart palpitations (13%), gastrointestinal infections (~ 10%), and agitation/feeling restless (~ 10%). CONCLUSIONS There is substantial body of evidence to suggest that MPH is an effective and safe treatment option for adults with ADHD.
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Affiliation(s)
- Rafał R Jaeschke
- Section of Affective Disorders, Department of Psychiatry, Jagiellonian University Medical College, ul. Kopernika 21a, 31-501, Kraków, Poland.
| | - Ewelina Sujkowska
- Department of Human Physiology, Institute of Medical Sciences, Medical College of Rzeszów University, ul. Kopisto 2a, 35-315, Rzeszów, Poland
| | - Magdalena Sowa-Kućma
- Department of Human Physiology, Institute of Medical Sciences, Medical College of Rzeszów University, ul. Kopisto 2a, 35-315, Rzeszów, Poland
- Centre for Innovative Research in Medical and Natural Sciences, Medical College of Rzeszów University, ul. Warzywna 1a, 35-310, Rzeszów, Poland
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Mucci F, Carpita B, Pagni G, Vecchia AD, Bjedov S, Pozza A, Marazziti D. Lifetime evolution of ADHD treatment. J Neural Transm (Vienna) 2021; 128:1085-98. [PMID: 33993352 DOI: 10.1007/s00702-021-02336-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD), has been traditionally considered a neurodevelopmental disorder affecting children and adolescents characterized by inattention, hyperactivity, disruptive behavior, and impulsivity. Although still debated, it is evident that ADHD is also present in adulthood, but this diagnosis is rarely carried out, mainly for the frequent comorbidity with other psychiatric and/or substance abuse disorders. Given the need to shed more light on the pharmacological treatment of ADHD, we performed a naturalistic review to review and comment on the available literature of ADHD treatment across the lifespan. Indeed, stimulants are endowed of a prompt efficacy and safety, whilst non-stimulants, although requiring some weeks to be fully effective, are useful when a substance abuse history is detected. In any case, the pharmacological management of ADHD appears to be still largely influenced by the individual experience of the clinicians. Further longitudinal studies with a careful and detailed characterization of participants across different phases of the lifespan are also required to provide relevant confirmations (or denials) regarding pharmacological treatments amongst the different age groups.
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Dipasquale O, Martins D, Sethi A, Veronese M, Hesse S, Rullmann M, Sabri O, Turkheimer F, Harrison NA, Mehta MA, Cercignani M. Unravelling the effects of methylphenidate on the dopaminergic and noradrenergic functional circuits. Neuropsychopharmacology 2020; 45:1482-1489. [PMID: 32473593 PMCID: PMC7360745 DOI: 10.1038/s41386-020-0724-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/30/2020] [Accepted: 05/15/2020] [Indexed: 11/08/2022]
Abstract
Functional magnetic resonance imaging (fMRI) can be combined with drugs to investigate the system-level functional responses in the brain to such challenges. However, most psychoactive agents act on multiple neurotransmitters, limiting the ability of fMRI to identify functional effects related to actions on discrete pharmacological targets. We recently introduced a multimodal approach, REACT (Receptor-Enriched Analysis of functional Connectivity by Targets), which offers the opportunity to disentangle effects of drugs on different neurotransmitters and clarify the biological mechanisms driving clinical efficacy and side effects of a compound. Here, we focus on methylphenidate (MPH), which binds to the dopamine transporter (DAT) and the norepinephrine transporter (NET), to unravel its effects on dopaminergic and noradrenergic functional circuits in the healthy brain at rest. We then explored the relationship between these target-enriched resting state functional connectivity (FC) maps and inter-individual variability in behavioural responses to a reinforcement-learning task encompassing a novelty manipulation to disentangle the molecular systems underlying specific cognitive/behavioural effects. Our main analysis showed a significant MPH-induced FC increase in sensorimotor areas in the functional circuit associated with DAT. In our exploratory analysis, we found that MPH-induced regional variations in the DAT and NET-enriched FC maps were significantly correlated with some of the inter-individual differences on key behavioural responses associated with the reinforcement-learning task. Our findings show that main MPH-related FC changes at rest can be understood through the distribution of DAT in the brain. Furthermore, they suggest that when compounds have mixed pharmacological profiles, REACT may be able to capture regional functional effects that are underpinned by the same cognitive mechanism but are related to engagement of distinct molecular targets.
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Affiliation(s)
- Ottavia Dipasquale
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
| | - Daniel Martins
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Arjun Sethi
- Forensic & Neurodevelopmental Sciences, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Mattia Veronese
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Swen Hesse
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany
- Integrated Research and Treatment Center (IFB) Adiposity Diseases, Leipzig University Medical Center, Leipzig, Germany
| | - Michael Rullmann
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany
- Integrated Research and Treatment Center (IFB) Adiposity Diseases, Leipzig University Medical Center, Leipzig, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany
| | - Federico Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Neil A Harrison
- Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, UK
| | - Mitul A Mehta
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Mara Cercignani
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, UK
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Xue W, Fu T, Zheng G, Tu G, Zhang Y, Yang F, Tao L, Yao L, Zhu F. Recent Advances and Challenges of the Drugs Acting on Monoamine Transporters. Curr Med Chem 2020; 27:3830-3876. [DOI: 10.2174/0929867325666181009123218] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/30/2018] [Accepted: 10/03/2018] [Indexed: 01/06/2023]
Abstract
Background:
The human Monoamine Transporters (hMATs), primarily including hSERT,
hNET and hDAT, are important targets for the treatment of depression and other behavioral disorders
with more than the availability of 30 approved drugs.
Objective:
This paper is to review the recent progress in the binding mode and inhibitory mechanism of
hMATs inhibitors with the central or allosteric binding sites, for the benefit of future hMATs inhibitor
design and discovery. The Structure-Activity Relationship (SAR) and the selectivity for hit/lead compounds
to hMATs that are evaluated by in vitro and in vivo experiments will be highlighted.
Methods:
PubMed and Web of Science databases were searched for protein-ligand interaction, novel
inhibitors design and synthesis studies related to hMATs.
Results:
Literature data indicate that since the first crystal structure determinations of the homologous
bacterial Leucine Transporter (LeuT) complexed with clomipramine, a sizable database of over 100 experimental
structures or computational models has been accumulated that now defines a substantial degree
of structural variability hMATs-ligands recognition. In the meanwhile, a number of novel hMATs
inhibitors have been discovered by medicinal chemistry with significant help from computational models.
Conclusion:
The reported new compounds act on hMATs as well as the structures of the transporters
complexed with diverse ligands by either experiment or computational modeling have shed light on the
poly-pharmacology, multimodal and allosteric regulation of the drugs to transporters. All of the studies
will greatly promote the Structure-Based Drug Design (SBDD) of structurally novel scaffolds with high
activity and selectivity for hMATs.
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Affiliation(s)
- Weiwei Xue
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Tingting Fu
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Guoxun Zheng
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Gao Tu
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Yang Zhang
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Fengyuan Yang
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Lin Tao
- Key Laboratory of Elemene Class Anti-cancer Chinese Medicine of Zhejiang Province, School of Medicine, Hangzhou Normal University, Hangzhou 310036, China
| | - Lixia Yao
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN 55905, United States
| | - Feng Zhu
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
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Lelong J, Brunet B, Afonso L, Voyer M, Richeval C, Humbert L, Sauvageon Y, Delbreil A, Mura P. Décès accidentel suite à une injection de B2 Ultra. Toxicologie Analytique et Clinique 2020. [DOI: 10.1016/j.toxac.2019.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Mucci F, Avella MT, Marazziti D. ADHD with Comorbid Bipolar Disorders: A Systematic Review of Neurobiological, Clinical and Pharmacological Aspects Across the Lifespan. Curr Med Chem 2020; 26:6942-6969. [PMID: 31385763 DOI: 10.2174/0929867326666190805153610] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/05/2018] [Accepted: 11/15/2018] [Indexed: 01/09/2023]
Abstract
BACKGROUND Attention deficit hyperactivity (ADHD) disorder is a neurodevelopmental disorder characterized by inattention, hyperactivity, disruptive behaviour, and impulsivity. Despite considered typical of children for a long time, the persistence of ADHD symptoms in adulthood gained increasing interest during the last decades. Indeed, its diagnosis, albeit controversial, is rarely carried out even because ADHD is often comorbid with several other psychiatric diosrders, in particular with bipolar disorders (BDs), a condition that complicates the clinical picture, assessment and treatment. AIMS The aim of this paper was to systematically review the scientific literature on the neurobiological, clinical features and current pharmacological management of ADHD comorbid with BDs across the entire lifespan, with a major focus on the adulthood. DISCUSSION The pharmacology of ADHD-BD in adults is still empirical and influenced by the individual experience of the clinicians. Stimulants are endowed of a prompt efficacy and safety, whilst non-stimulants are useful when a substance abuse history is detected, although they require some weeks in order to be fully effective. In any case, an in-depth diagnostic and clinical evaluation of the single individual is mandatory. CONCLUSION The comorbidity of ADHD with BD is still a controversial matter, as it is the notion of adult ADHD as a distinct nosological category. Indeed, some findings highlighted the presence of common neurobiological mechanisms and overlapping clinical features, although disagreement does exist. In any case, while expecting to disentangle this crucial question, a correct management of this comorbidity is essential, which requires the co-administration of mood stabilizers. Further controlled clinical studies in large samples of adult ADHD-BD patients appear extremely urgent in order to better define possible therapeutic guidelines, as well as alternative approaches for this potentially invalidating condition.
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Affiliation(s)
- Federico Mucci
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Fondazione BRF, Istituto per la Ricerca Scientifica in Psichiatria e Neuroscienze, Lucca, Italy
| | - Maria Teresa Avella
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Donatella Marazziti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Fondazione BRF, Istituto per la Ricerca Scientifica in Psichiatria e Neuroscienze, Lucca, Italy
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Robins MT, Blaine AT, Ha JE, Brewster AL, van Rijn RM. Repeated Use of the Psychoactive Substance Ethylphenidate Impacts Neurochemistry and Reward Learning in Adolescent Male and Female Mice. Front Neurosci 2019; 13:124. [PMID: 30837836 PMCID: PMC6389692 DOI: 10.3389/fnins.2019.00124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 02/04/2019] [Indexed: 02/03/2023] Open
Abstract
Schedule II prescription psychostimulants, such as methylphenidate (MPH), can be misused as nootropic drugs, i.e., drugs that enhance focus and cognition. When users are unable to obtain these prescribed medications, they may seek out novel psychoactive substances (NPSs) that are not yet scheduled. An example of a NPS reportedly being abused is ethylphenidate (EPH), a close analog of MPH but with a higher preference for the dopamine transporter compared with the norepinephrine transporter. Therefore, based upon this pharmacological profile and user self-reports, we hypothesized that repeated EPH exposure in adolescent mice may be rewarding and alter cognition. Here, we report that repeated exposure to 15 mg/kg EPH decreased spatial cognitive performance as assessed by the Barnes maze spatial learning task in adolescent male C57Bl/6 mice; however, male mice did not show alterations in the expression of mature BDNF - a protein associated with increased cognitive function - in key brain regions. Acute EPH exposure induced hyperlocomotion at a high dose (15 mg/kg, i.p.), but not a low dose (5 mg/kg, i.p.). Interestingly, mice exhibited significant conditioned place preference at the low EPH dose, suggesting that even non-stimulating doses of EPH are rewarding. In both males and females, repeated EPH exposure increased expression of deltaFosB - a marker associated with increased risk of drug abuse - in the dorsal striatum, nucleus accumbens, and prefrontal cortex. Overall, our results suggest that repeated EPH use in adolescence is psychostimulatory, rewarding, increases crucial brain markers of reward-related behaviors, and may negatively impact spatial performance.
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Affiliation(s)
- Meridith T Robins
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Arryn T Blaine
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States.,Purdue Interdisciplinary Life Sciences Graduate Program, Purdue University, West Lafayette, IN, United States
| | - Jiwon E Ha
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Amy L Brewster
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States.,Purdue Interdisciplinary Life Sciences Graduate Program, Purdue University, West Lafayette, IN, United States.,Department of Psychological Sciences, Purdue University, West Lafayette, IN, United States
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States.,Purdue Interdisciplinary Life Sciences Graduate Program, Purdue University, West Lafayette, IN, United States
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Knych HK, McKemie DS, Seminoff K, Hartmann P, Hovda L, Benson D. L- and D-threo ethylphenidate concentrations, pharmacokinetics, and pharmacodynamics in horses. Drug Test Anal 2018; 10:1508-1517. [PMID: 29786965 DOI: 10.1002/dta.2408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/09/2022]
Abstract
Ethylphenidate is a psychostimulant and analog of the commonly prescribed compound, methylphenidate (Ritalin®). There are a limited number of studies describing the disposition and pharmacologic/toxicological effects of ethylphenidate in any species. The abuse potential in equine athletes along with the limited data available regarding administration in horses necessitates further study. The objectives of the current study were to describe drug concentrations, develop an analytical method that could be used to regulate its use, and describe the pharmacodynamic effects of ethylphenidate in horses. To that end, 12 horses were randomized into 3 dose groups (intravenous: 10 mg or 40 mg, oral: 40 mg). Ethylphenidate was administered and blood and urine samples were collected prior to and for up to 72 hours post drug administration. Concentrations of D-threo ethylphenidate and the metabolite ritalinic acid were measured using Liquid Chromatography-tandem Mass Spectrometry. L-threo ethylphenidate concentrations were estimated from D-threo ethylphenidate concentrations. Serum concentrations of ethylphenidate were below detectable levels by 8, 18, and 12 hours following intravenous administration of 10 mg and 40 mg and oral administration of 40 mg, respectively. Ritalinic acid was non-detectable at 72 hours in the group that received a 10-mg intravenous and 40-mg oral dose of ethylphenidate. Ritalinic acid concentrations were below the LOQ at 72 hours following intravenous administration of 40 mg of ethylphenidate. While the number of animals per dose group were small, no stimulatory behavior or significant changes in heart rate were noted. Untoward effects including gastrointestinal adverse effects were noted in all dose groups.
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Affiliation(s)
- Heather K Knych
- K.L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, California.,Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California
| | - Dan S McKemie
- K.L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, California
| | - Kelsey Seminoff
- K.L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, California
| | | | - Lynn Hovda
- Minnesota Racing Commission, Shakopee, Minnesota
| | - Dionne Benson
- Racing Medication and Testing Consortium, Lexington, Kentucky
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Zhu HJ, Patrick KS, Straughn AB, Reeves OT 3rd, Bernstein H, Shi J, Johnson HJ, Knight JM, Smith AT, Malcolm RJ, Markowitz JS. Ethanol Interactions With Dexmethylphenidate and dl-Methylphenidate Spheroidal Oral Drug Absorption Systems in Healthy Volunteers. J Clin Psychopharmacol 2017; 37:419-28. [PMID: 28590363 DOI: 10.1097/JCP.0000000000000721] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND/PURPOSE Ethanol coadministered with immediate-release dl-methylphenidate (dl-MPH) or dexmethylphenidate (d-MPH) significantly increases the geomean maximum plasma concentration (Cmax) of d-MPH 22% and 15%, respectively, and elevates overall drug exposure and psychostimulant effects. We asked the question: Are these ethanol-MPH interactions based more fundamentally on (1) inhibition of postabsorption d-MPH metabolism or (2) acceleration of MPH formulation gastric dissolution by ethanol in the stomach? This was investigated using the pulsatile, distinctly biphasic, spheroidal oral drug absorption systems of dl-MPH and d-MPH. METHODS In a randomized, 4-way crossover study, 14 healthy subjects received pulsatile dl-MPH (40 mg) or d-MPH (20 mg), with or without ethanol (0.6 g/kg), dosed 4 hours later. These 4 hours allowed the delayed-release second MPH pulse to reach a more distal region of the gut to preclude gastric biopharmaceutical influences. Plasma was analyzed using a highly sensitive chiral method. Subjective/physiological effects were recorded. FINDINGS/RESULTS Ethanol increased the second pulse of d-MPH Cmax for dl-MPH by 35% (P < 0.01) and the partial area under the plasma concentration curve from 4 to 8 hours by 25% (P < 0.05). The respective values for enantiopure d-MPH were 27% (P = 0.001) and 20% (P < 0.01). The carboxylesterase 1-mediated transesterification metabolite ethylphenidate served as a biomarker for coexposure. Ethanol significantly potentiated stimulant responses to either formulation. IMPLICATIONS/CONCLUSIONS These findings support drug dispositional interactions between ethanol and MPH as dominant over potential biopharmaceutical considerations. Understanding the pharmacology underlying the frequent coabuse of MPH-ethanol provides rational guidance in the selection of first-line pharmacotherapy for comorbid attention-deficit/hyperactivity disorder-alcohol use disorder.
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Wang P, Fu T, Zhang X, Yang F, Zheng G, Xue W, Chen Y, Yao X, Zhu F. Differentiating physicochemical properties between NDRIs and sNRIs clinically important for the treatment of ADHD. Biochim Biophys Acta Gen Subj 2017; 1861:2766-2777. [PMID: 28757337 DOI: 10.1016/j.bbagen.2017.07.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/23/2017] [Accepted: 07/26/2017] [Indexed: 12/25/2022]
Abstract
BACKGROUND Drugs available for treating attention-deficit hyperactivity disorder (ADHD) are mainly selective norepinephrine (sNRIs) and dual norepinephrine-dopamine (NDRIs) reuptake inhibitors. The major problem of sNRIs lines in their delayed onset of action and partial- or non-responses, which makes NDRIs distinguished in drug efficacy. Understanding of the differential binding modes of these 2 types of drugs to their corresponding targets can give great insights into the discovery of privileged drug-like scaffolds with improved efficacy. So far, no such study has been carried out. METHODS A combinatorial computational strategy, integrating homology modeling, molecular docking, molecular dynamics (MD) and binding free energy calculation, was employed to analyze the binding modes of 8 clinically important ADHD drugs in their targets. RESULTS Binding modes of 2 types of ADHD drugs (sNRIs and NDRIs) in their targets was identified for the first time by MD simulation, and 15 hot spot residues were discovered as crucial for NDRIs' binding in hNET and hDAT. Comparing to sNRIs, a clear reduction in the hydrophobic property of NDRIs' one functional group was observed, and the depth of drugs' aromatic ring stretched into the pocket of both targets was further identified as key contributors to drugs' selectivity. CONCLUSIONS The hydrophobic property of NDRI ADHD drugs' one functional group contributes to their selectivity when bind hNET and hDAT. GENERAL SIGNIFICANCE These results provide insights into NDRI ADHD drugs' binding mechanisms, which could be utilized as structural blueprints for assessing and discovering more efficacious drugs for ADHD therapy.
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Affiliation(s)
- Panpan Wang
- Innovative Drug Research and Bioinformatics Group, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; College of Chemistry and Pharmaceutical Engineering, Huanghuai University, Zhumadian 463000, China; School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Tingting Fu
- Innovative Drug Research and Bioinformatics Group, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Xiaoyu Zhang
- Innovative Drug Research and Bioinformatics Group, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Fengyuan Yang
- Innovative Drug Research and Bioinformatics Group, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Guoxun Zheng
- Innovative Drug Research and Bioinformatics Group, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Weiwei Xue
- School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China.
| | - Yuzong Chen
- Bioinformatics and Drug Design Group, Department of Pharmacy, National University of Singapore, Singapore 117543, Singapore
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Feng Zhu
- Innovative Drug Research and Bioinformatics Group, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; School of Pharmaceutical Sciences and Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 401331, China.
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Wang P, Zhang X, Fu T, Li S, Li B, Xue W, Yao X, Chen Y, Zhu F. Differentiating Physicochemical Properties between Addictive and Nonaddictive ADHD Drugs Revealed by Molecular Dynamics Simulation Studies. ACS Chem Neurosci 2017; 8:1416-1428. [PMID: 28557437 DOI: 10.1021/acschemneuro.7b00173] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed mental disorder of children and adolescents. Although psychostimulants are currently the first-line drugs for ADHD, their highly addictive profile raises great abuse concerns. It is known that psychostimulants' addictiveness is largely attributed to their interaction with dopamine transporter (DAT) and their binding modes in DAT can thus facilitate the understanding of the mechanism underlining drugs' addictiveness. However, no DAT residue able to discriminate ADHD drugs' addictiveness is identified, and the way how different drug structures affect their abuse liability is still elusive. In this study, multiple computational methods were integrated to differentiate binding modes between approved psychostimulants and ADHD drugs of little addictiveness. As a result, variation in energy contribution of 8 residues between addictive and nonaddictive drugs was observed, and a reduction in hydrophobicity of drugs' 2 functional groups was identified as the indicator of drugs' addictiveness. This finding agreed well with the physicochemical properties of 8 officially reported controlled substances. The identified variations in binding mode can shed light on the mechanism underlining drugs' addictiveness, which may thus facilitate the discovery of improved ADHD therapeutics with reduced addictive profile.
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Affiliation(s)
- Panpan Wang
- College of Pharmaceutical
Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Xiaoyu Zhang
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Tingting Fu
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Shuang Li
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Bo Li
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Weiwei Xue
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic
Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Yuzong Chen
- Bioinformatics and
Drug Design Group, Department of Pharmacy, National University of Singapore, Singapore 117543, Singapore
| | - Feng Zhu
- College of Pharmaceutical
Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Maskell P, Smith P, Cole R, Hikin L, Morley S. Seven fatalities associated with ethylphenidate. Forensic Sci Int 2016; 265:70-4. [DOI: 10.1016/j.forsciint.2015.12.045] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/19/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
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Dinis-oliveira RJ. Metabolomics of Methylphenidate and Ethylphenidate: Implications in Pharmacological and Toxicological Effects. Eur J Drug Metab Pharmacokinet 2017; 42:11-6. [DOI: 10.1007/s13318-016-0362-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Patrick KS, Straughn AB, Reeves OT 3rd, Bernstein H, Malcolm R. Comparative Ethanol-Induced Potentiation of Stimulatory Responses to Dexmethylphenidate Versus Methylphenidate. J Clin Psychopharmacol 2015; 35:464-7. [PMID: 26075488 DOI: 10.1097/JCP.0000000000000348] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The potentiation of positive subjective responses to immediate-release dexmethylphenidate (d-MPH) or dl-methylphenidate (dl-MPH) by ethanol was investigated over the time course of maximal drug exposure after a single dose. In a 4-way, randomized, crossover study design, 12 men and 12 women normal volunteers received d-MPH (0.15 mg/kg) or dl-MPH (0.3 mg/kg) with or without ethanol (0.6 g/kg). Serial visual analog scales were used as surrogates for drug abuse liability ("high," "good," "like," "stimulated," and "any drug effect"). Combining pure d-MPH with ethanol significantly (P < 0.005) increased the area under the effect curves (AUC(0-5.25h)) of all 5 subscales. The dl-MPH-ethanol combination significantly (P < 0.05) increased these AUCs with the exception of like (P = 0.08). Effects of the pure d-MPH-ethanol combination exhibited delayed potentiation relative to dl-MPH-ethanol. A pharmacokinetic interaction between the l-isomer of dl-MPH and ethanol has previously been shown to increase early exposure to d-MPH. Administration of the pure isomer d-MPH precludes this absorption phase pharmacokinetic interaction with ethanol. This notwithstanding, the pure d-MPH-ethanol combination resulted in comparable, if not greater, cumulative stimulant potentiation than the dl-MPH-ethanol combination. These findings provide evidence of a pharmacodynamic component to d-MPH-ethanol synergistic interactions and carry implications for the rational drug individualization in the treatment of attention-deficit/hyperactivity disorder.
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Ho JH, Bailey GP, Archer JRH, Dargan PI, Wood DM. Ethylphenidate: availability, patterns of use, and acute effects of this novel psychoactive substance. Eur J Clin Pharmacol 2015. [DOI: 10.1007/s00228-015-1906-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Santacroce R, Corazza O, Martinotti G, Bersani FS, Valeriani G, Di Giannantonio M. Psyclones: a roller coaster of life? Hidden synthetic cannabinoids and stimulants in apparently harmless products. Hum Psychopharmacol 2015. [PMID: 26216561 DOI: 10.1002/hup.2410] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The urge to gain information on a new drug marketed online as 'Psyclone' has emerged after the death of a 38-year-old man in Bolton (UK). The fatality appeared to be a consequence of smoking this psychoactive product. METHODS From October to December 2013, qualitative searches of the Web have been carried out in English and Italian, using the keywords 'Psyclone', 'Psyclone legal high', 'Psyclone incense' and 'Psyclone research chemical' on the Google search engine and on the database provided by the Global Public Health Intelligence Network. RESULTS Our research highlighted the existence of two psychoactive products labelled as Psyclone but with different contents and packaging: a herbal blend containing two synthetic cannabinoids (AKB-48 and 5f-PB-22) and a research chemical containing 50% ethylphenidate, 30% caffeine and 20% lidocaine. Desired and side effects of both compounds are explored in the paper. CONCLUSIONS Being sold as a legal product, Psyclone may appeal to recreational users, who remain unaware of its real content. This is a serious public health threat, which may lead to acute intoxications and fatalities. Further studies in the field, including Internet monitoring, are therefore required.
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Affiliation(s)
- Rita Santacroce
- Department of Neuroscience and Imaging, University 'G. d'Annunzio', Chieti, Italy.,School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK
| | - Ornella Corazza
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK
| | - Giovanni Martinotti
- Department of Neuroscience and Imaging, University 'G. d'Annunzio', Chieti, Italy
| | - Francesco Saverio Bersani
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK.,Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Giuseppe Valeriani
- Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
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McGovern R, Luderman L, Knecht K, Griffin WC 3rd. Influence of sensitization on the discriminative stimulus effects of methylphenidate in mice. Behav Pharmacol 2014; 25:766-74. [PMID: 25325285 DOI: 10.1097/FBP.0000000000000095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [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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22
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Patrick KS, Corbin TR, Murphy CE. Ethylphenidate as a selective dopaminergic agonist and methylphenidate-ethanol transesterification biomarker. J Pharm Sci 2014; 103:3834-3842. [PMID: 25303048 DOI: 10.1002/jps.24202] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/18/2014] [Accepted: 09/18/2014] [Indexed: 01/19/2023]
Abstract
We review the pharmaceutical science of ethylphenidate (EPH) in the contexts of drug discovery, drug interactions, biomarker for dl-methylphenidate (MPH)-ethanol exposure, potentiation of dl-MPH abuse liability, contemporary "designer drug," pertinence to the newer transdermal and chiral switch MPH formulations, as well as problematic internal standard. d-EPH selectively targets the dopamine transporter, whereas d-MPH exhibits equipotent actions at dopamine and norepinephrine transporters. This selectivity carries implications for the advancement of tailored attention-deficit/hyperactivity disorder (ADHD) pharmacotherapy in the era of genome-based diagnostics. Abuse of dl-MPH often involves ethanol coabuse. Carboxylesterase 1 enantioselectively transesterifies l-MPH with ethanol to yield l-EPH accompanied by significantly increased early exposure to d-MPH and rapid potentiation of euphoria. The pharmacokinetic component of this drug interaction can largely be avoided using dexmethylphenidate (dexMPH). This notwithstanding, maximal potentiated euphoria occurs following dexMPH-ethanol. C57BL/6 mice model dl-MPH-ethanol interactions: an otherwise depressive dose of ethanol synergistically increases dl-MPH stimulation; a substimulatory dose of dl-MPH potentiates a low, stimulatory dose of ethanol; ethanol elevates blood, brain, and urinary d-MPH concentrations while forming l-EPH. Integration of EPH preclinical neuropharmacology with clinical studies of MPH-ethanol interactions provides a translational approach toward advancement of ADHD personalized medicine and management of comorbid alcohol use disorder.
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Affiliation(s)
- Kennerly S Patrick
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina 29425-1400.
| | - Timothy R Corbin
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina 29425-1400
| | - Cristina E Murphy
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina 29425-1400
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Krueger J, Sachs H, Musshoff F, Dame T, Schaeper J, Schwerer M, Graw M, Roider G. First detection of ethylphenidate in human fatalities after ethylphenidate intake. Forensic Sci Int 2014; 243:126-9. [DOI: 10.1016/j.forsciint.2014.07.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 06/18/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022]
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Markowitz JS, Zhu HJ, Patrick KS. Isopropylphenidate: an ester homolog of methylphenidate with sustained and selective dopaminergic activity and reduced drug interaction liability. J Child Adolesc Psychopharmacol 2013; 23:648-54. [PMID: 24261661 DOI: 10.1089/cap.2013.0074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
OBJECTIVE The most widely utilized pharmacological treatment of attention-deficit/hyperactivity disorder (ADHD) is the psychostimulant methylphenidate (MPH). Most MPH formulations consist of the racemic mixture of d-threo-(R, R)-MPH and l-threo-(S, S)-MPH isomers. MPH is characterized by its low bioavailability and short half-life (2-3 hours). Additionally, significant inter-individual variability in MPH pharmacokinetics has been consistently documented. Accordingly, efforts have been directed at developing alternatives to MPH as therapeutic agents. A wide range of MPH analogues (dl-α-[2-piperidyl]-phenylacetic acid esters) have been synthesized with the dopamine transporter (DAT) and norepinephrine transporter (NET) as principle neuropharmacological targets. The present study investigated the metabolic profiles and pharmacological activity of the isopropyl ester derivative of MPH, dl-isopropylphenidate (IPH), both in vitro and in vivo. METHODS The synthesis, monoaminergic transporter binding, cellular uptake profiles, and assessment of metabolic hydrolysis and transesterification in the presence of ethanol are described using MPH as a comparator. Additionally, an in vivo assessment of IPH stimulant effects (vs. saline) in rats was performed with locomotor activity as a pharmacodynamic outcome. RESULTS IPH displayed unique pharmacological characteristics including greater DAT than NET binding and cellular uptake activity, and greater resistance to hydrolysis and transesterification via carboxylesterase 1 relative to MPH. Further, sustained psychostimulant properties offer the prospect of an enhanced duration of action. CONCLUSIONS Our findings are consistent with IPH exhibiting attributes distinguishing it from MPH and warranting further study and development of IPH as a novel psychotherapeutic agent.
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Affiliation(s)
- John S Markowitz
- 1 Department of Pharmacotherapy and Translational Research, University of Florida , Gainesville, Florida
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Affiliation(s)
- John S. Markowitz
- 1 Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, Florida
- 2 Center for Pharmacogenomics, University of Florida, Gainesville, Florida
| | - Kennerly S. Patrick
- 3 Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina
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Griffin WC, McGovern RW, Bell GH, Randall PK, Middaugh LD, Patrick KS. Interactive effects of methylphenidate and alcohol on discrimination, conditioned place preference and motor coordination in C57BL/6J mice. Psychopharmacology (Berl) 2013; 225:613-25. [PMID: 22955568 PMCID: PMC3547134 DOI: 10.1007/s00213-012-2849-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/10/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Prior research indicates methylphenidate (MPH) and alcohol (ethanol, EtOH) interact to significantly affect responses humans and mice. The present studies tested the hypothesis that MPH and EtOH interact to potentiate ethanol-related behaviors in mice. METHODS We used several behavioral tasks including: drug discrimination in MPH-trained and EtOH-trained mice, conditioned place preference (CPP), rota-rod and the parallel rod apparatus. We also used gas chromatographic methods to measure brain tissue levels of EtOH and the D- and L-isomers of MPH and the metabolite, ethylphenidate (EPH). RESULTS In discrimination, EtOH (1 g/kg) produced a significant leftward shift in the MPH generalization curve (1-2 mg/kg) for MPH-trained mice, but no effects of MPH (0.625-1.25 mg/kg) on EtOH discrimination in EtOH-trained mice (0-2.5 g/kg) were observed. In CPP, the MPH (1.25 mg/kg) and EtOH (1.75 g/kg) combination significantly increased time on the drug paired side compared to vehicle (30.7 %), but this was similar to MPH (28.8 %) and EtOH (33.6 %). Footslip errors measured in a parallel rod apparatus indicated that the drug combination was very ataxic, with footslips increasing 29.5 % compared to EtOH. Finally, brain EtOH concentrations were not altered by 1.75 g/kg EtOH combined with 1.25 mg/kg MPH. However, EtOH significantly increased D-MPH and L-EPH without changing L-MPH brain concentrations. CONCLUSIONS The enhanced behavioral effects when EtOH is combined with MPH are likely due to the selective increase in brain D-MPH concentrations. These studies are consistent with observations in humans of increased interoceptive awareness of the drug combination and provide new clinical perspectives regarding enhanced ataxic effects of this drug combination.
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Affiliation(s)
- William C. Griffin
- Charleston Alcohol Research Center, Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Science, Medical University of South Carolina, Charleston, SC 29425-0742
| | | | - Guinevere H. Bell
- Department of Pharmaceutical and Biomedical Sciences Medical University of South Carolina, Charleston, SC 29425-0742
| | - Patrick K. Randall
- Charleston Alcohol Research Center, Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Science, Medical University of South Carolina, Charleston, SC 29425-0742
| | - Lawrence D. Middaugh
- Charleston Alcohol Research Center, Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Science, Medical University of South Carolina, Charleston, SC 29425-0742
,Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425-0742
| | - Kennerly S. Patrick
- Department of Pharmaceutical and Biomedical Sciences Medical University of South Carolina, Charleston, SC 29425-0742
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Patrick KS, Straughn AB, Reeves OT, Bernstein H, Bell GH, Anderson ER, Malcolm RJ. Differential influences of ethanol on early exposure to racemic methylphenidate compared with dexmethylphenidate in humans. Drug Metab Dispos 2012; 41:197-205. [PMID: 23104969 DOI: 10.1124/dmd.112.048595] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Enantioselective hydrolysis of oral racemic methylphenidate (dl-MPH) by carboxylesterase 1 (CES1) limits the absolute bioavailability of the pharmacologically active d-MPH isomer to approximately 30% and that of the inactive l-MPH to only 1-2%. Coadministration of dl-MPH with ethanol results in elevated d-MPH plasma concentrations accompanied by CES1-mediated enantioselective transesterification of l-MPH to l-ethylphenidate (EPH). The present study tested the hypothesis that administration of the pure isomer dexmethylphenidate (d-MPH) will overcome the influence of ethanol on d-MPH absorption by eliminating competitive CES1-mediated presystemic metabolism of l-MPH to l-EPH. Twenty-four healthy volunteers received dl-MPH (0.3 mg/kg) or d-MPH (0.15 mg/kg), with or without ethanol (0.6 g/kg). During the absorption phase of dl-MPH, concomitant ethanol significantly elevated d-MPH plasma concentrations (44-99%; P < 0.005). Furthermore, immediately following the ethanol drink the subjective effects of "high," "good," "like," "stimulated," and overall "effect" were significantly potentiated (P ≤ 0.01). Plasma l-EPH concentrations exceeded those of l-MPH. Ethanol combined with pure d-MPH did not elevate plasma d-MPH concentrations during the absorption phase, and the ethanol-induced potentiation of subjective effects was delayed relative to dl-MPH-ethanol. These findings are consistent with l-MPH competitively inhibiting presystemic CES1 metabolism of d-MPH. Ethanol increased the d-MPH area under the curve (AUC)(0-inf) by 21% following dl-MPH (P < 0.001) and 14% for d-MPH (P = 0.001). In men receiving d-MPH-ethanol, the d-MPH absorption partial AUC(0.5-2 hours) was 2.1 times greater and the time to maximum concentration (T(max)) occurred 1.1 hours earlier than in women, consistent with an increased rate of d-MPH absorption reducing hepatic extraction. More rapid absorption of d-MPH carries implications for increased abuse liability.
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Affiliation(s)
- Kennerly S Patrick
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, USA.
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Schmitt KC, Reith ME. The atypical stimulant and nootropic modafinil interacts with the dopamine transporter in a different manner than classical cocaine-like inhibitors. PLoS One 2011; 6:e25790. [PMID: 22043293 DOI: 10.1371/journal.pone.0025790] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 09/11/2011] [Indexed: 11/19/2022] Open
Abstract
Modafinil is a mild psychostimulant with pro-cognitive and antidepressant effects. Unlike many conventional stimulants, modafinil has little appreciable potential for abuse, making it a promising therapeutic agent for cocaine addiction. The chief molecular target of modafinil is the dopamine transporter (DAT); however, the mechanistic details underlying modafinil's unique effects remain unknown. Recent studies suggest that the conformational effects of a given DAT ligand influence the magnitude of the ligand's reinforcing properties. For example, the atypical DAT inhibitors benztropine and GBR12909 do not share cocaine's notorious addictive liability, despite having greater binding affinity. Here, we show that the binding mechanism of modafinil is different than cocaine and similar to other atypical inhibitors. We previously established two mutations (W84L and D313N) that increase the likelihood that the DAT will adopt an outward-facing conformational state—these mutations increase the affinity of cocaine-like inhibitors considerably, but have little or opposite effect on atypical inhibitor binding. Thus, a compound's WT/mutant affinity ratio can indicate whether the compound preferentially interacts with a more outward- or inward-facing conformational state. Modafinil displayed affinity ratios similar to those of benztropine, GBR12909 and bupropion (which lack cocaine-like effects in humans), but far different than those of cocaine, β-CFT or methylphenidate. Whereas treatment with zinc (known to stabilize an outward-facing transporter state) increased the affinity of cocaine and methylphenidate two-fold, it had little or no effect on the binding of modafinil, benztropine, bupropion or GBR12909. Additionally, computational modeling of inhibitor binding indicated that while β-CFT and methylphenidate stabilize an “open-to-out” conformation, binding of either modafinil or bupropion gives rise to a more closed conformation. Our findings highlight a mechanistic difference between modafinil and cocaine-like stimulants and further demonstrate that the conformational effects of a given DAT inhibitor influence its phenomenological effects.
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Bell GH, Griffin WC, Patrick KS. Oral and transdermal DL-methylphenidate-ethanol interactions in C57BL/6J mice: potentiation of locomotor activity with oral delivery. Pharmacol Biochem Behav 2011; 100:264-70. [PMID: 21925201 DOI: 10.1016/j.pbb.2011.08.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 08/24/2011] [Accepted: 08/30/2011] [Indexed: 11/18/2022]
Abstract
PURPOSE Many abusers of dl-methylphenidate co-abuse ethanol. The present animal study examined behavioral effects of oral or transdermal DL-methylphenidate in combination with a high, depressive dose of ethanol to model co-abuse. METHODS Locomotor activity of C57BL/6J mice was recorded for 3 h following dosing with either oral DL-methylphenidate (7.5 mg/kg) or transdermal DL-methylphenidate (Daytrana®;1/4 of a 12.5 cm(2) patch; mean dose 7.5 mg/kg), with or without oral ethanol (3 g/kg). Brains were enantiospecifically analyzed for the isomers of methylphenidate and the transesterification metabolite ethylphenidate. RESULTS An otherwise depressive dose of ethanol significantly potentiated oral DL-methylphenidate induced increases in total distance traveled for the first 100 min (p<0.05). Transdermal DL-methylphenidate increased total distance traveled after a latency of 80 min, though this effect was not potentiated by concomitant ethanol. Mean 3 h brain D-methylphenidate concentrations were significantly elevated by ethanol in both the oral (65% increase) and transdermal (88% increase) groups. The corresponding L-ethylphenidate concentrations were 10 ng/g and 130 ng/g. CONCLUSIONS Stimulant induced motor activity in rodents may correlate with abuse liability. Potentiation of DL-methylphenidate motor effects by concomitant ethanol carries implications regarding increased abuse potential of DL-methylphenidate when combined with ethanol.
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Affiliation(s)
- Guinevere H Bell
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, SC, United States.
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Bell GH, Novak AJ, Griffin WC, Patrick KS. Transdermal and oral dl-methylphenidate-ethanol interactions in C57BL/6J mice: transesterification to ethylphenidate and elevation of d-methylphenidate concentrations. J Pharm Sci 2011; 100:2966-78. [PMID: 21240977 DOI: 10.1002/jps.22476] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 10/12/2010] [Accepted: 12/13/2010] [Indexed: 01/17/2023]
Abstract
We tested the hypothesis that C57BL/6J mice will model human metabolic interactions between dl-methylphenidate (MPH) and ethanol, placing an emphasis on the MPH transdermal system (MTS). Specifically, we asked: (1) will ethanol increase d-MPH biological concentrations, (2) will MTS facilitate the systemic bioavailability of l-MPH, and (3) will l-MPH enantioselectively interact with ethanol to yield l-ethylphenidate (l-EPH)? Mice were dosed with MTS (¼ of a 12.5 cm(2) patch on shaved skin) or a comparable oral dl-MPH dose (7.5 mg/kg), with or without ethanol (3.0 g/kg), and then placed in metabolic cages for 3 h. MPH and EPH isomer concentrations in blood, brain, and urine were analyzed by gas chromatographic-mass spectrometry monitoring of N-(S)-prolylpiperidyl fragments. As in humans, MTS greatly facilitated the absorption of l-MPH in this mouse strain. Similarly, ethanol led to the enantioselective formation of l-EPH and to an elevation in d-MPH concentrations with both MTS and oral MPH. Although only guarded comparisons between MTS and oral MPH can be made due to route-dependent drug absorption rate differences, MTS was associated with significant MPH-ethanol interactions. Ethanol-mediated increases in circulating concentrations of d-MPH carry toxicological and abuse liability implications should this animal model hold for ethanol-consuming attention-deficit hyperactivity disorder patients or coabusers.
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Affiliation(s)
- Guinevere H Bell
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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McGovern RW, Middaugh LD, Patrick KS, Griffin WC 3rd. The discriminative stimulus properties of methylphenidate in C57BL/6J mice. Behav Pharmacol 2011; 22:14-22. [PMID: 21160424 DOI: 10.1097/FBP.0b013e3283423d92] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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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Thanos PK, Bermeo C, Rubinstein M, Suchland KL, Wang GJ, Grandy DK, Volkow ND. Conditioned place preference and locomotor activity in response to methylphenidate, amphetamine and cocaine in mice lacking dopamine D4 receptors. J Psychopharmacol 2010; 24:897-904. [PMID: 19282420 PMCID: PMC2878389 DOI: 10.1177/0269881109102613] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Methylphenidate (MP) and amphetamine (AMPH) are the most frequently prescribed medications for the treatment of attention-deficit/hyperactivity disorder (ADHD). Both drugs are believed to derive their therapeutic benefit by virtue of their dopamine (DA)-enhancing effects, yet an explanation for the observation that some patients with ADHD respond well to one medication but not to the other remains elusive. The dopaminergic effects of MP and AMPH are also thought to underlie their reinforcing properties and ultimately their abuse. Polymorphisms in the human gene that codes for the DA D4 receptor (D4R) have been repeatedly associated with ADHD and may correlate with the therapeutic as well as the reinforcing effects of responses to these psychostimulant medications. Conditioned place preference (CPP) for MP, AMPH and cocaine were evaluated in wild-type (WT) mice and their genetically engineered littermates, congenic on the C57Bl/6J background, that completely lack D4Rs (knockout or KO). In addition, the locomotor activity in these mice during the conditioning phase of CPP was tested in the CPP chambers. D4 receptor KO and WT mice showed CPP and increased locomotor activity in response to each of the three psychostimulants tested. D4R differentially modulates the CPP responses to MP, AMPH and cocaine. While the D4R genotype affected CPP responses to MP (high dose only) and AMPH (low dose only) it had no effects on cocaine. Inasmuch as CPP is considered an indicator of sensitivity to reinforcing responses to drugs these data suggest a significant but limited role of D4Rs in modulating conditioning responses to MP and AMPH. In the locomotor test, D4 receptor KO mice displayed attenuated increases in AMPH-induced locomotor activity whereas responses to cocaine and MP did not differ. These results suggest distinct mechanisms for D4 receptor modulation of the reinforcing (perhaps via attenuating dopaminergic signalling) and locomotor properties of these stimulant drugs. Thus, individuals with D4 receptor polymorphisms might show enhanced reinforcing responses to MP and AMPH and attenuated locomotor response to AMPH.
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Affiliation(s)
- P K Thanos
- Laboratory of Neuroimaging, NIAAA Intramural Program, NIH, Bethesda, MD, USA.
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Griffin WC 3rd, Novak AJ, Middaugh LD, Patrick KS. The interactive effects of methylphenidate and ethanol on ethanol consumption and locomotor activity in mice. Pharmacol Biochem Behav 2010; 95:267-72. [PMID: 20122954 DOI: 10.1016/j.pbb.2010.01.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/20/2010] [Accepted: 01/26/2010] [Indexed: 12/19/2022]
Abstract
The concomitant use of alcohol (EtOH) and the psychotherapeutic agent dl-methylphenidate (MPH) has risen as a consequence of an increase in ADHD diagnoses within the drinking age population. It was recently found that the combination of MPH and EtOH increases the self-report of pleasurable feelings relative to MPH alone. This finding raises concerns regarding the combined abuse liability for these two widely used drugs. The present behavioral study reports on the development of an adult male C57BL/6J (B6) mouse model to further characterize this MPH-EtOH interaction. We examined the effects of MPH on EtOH consumption in a limited access paradigm and EtOH stimulation of locomotor activity. B6 mice consumed about 2g/kg EtOH daily and MPH dose-dependently reduced drinking. The most effective dose of MPH was 1.25mg/kg, which produced a 41% decrease in drinking and had no effect on locomotor activity. However, when the 1.25mg/kg dose of MPH was combined with a stimulatory dose of ethanol (1.75g/kg) by intraperitoneal injection, there was a significantly enhanced stimulation of locomotor activity. The drug combination increased activity compared to the vehicle or MPH injections by 45% and increased the activity relative to EtOH alone by an additional 25%. The results of the EtOH and MPH interactions observed with the mouse model appear to be behaviorally relevant and suggest several converging mechanisms that may underlie MPH-EtOH interactions.
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Issy A, Salum C, Del Bel E. Nitric oxide modulation of methylphenidate-induced disruption of prepulse inhibition in Swiss mice. Behav Brain Res 2009; 205:475-81. [DOI: 10.1016/j.bbr.2009.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 07/29/2009] [Accepted: 08/03/2009] [Indexed: 11/24/2022]
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Abstract
OBJECTIVE The following comprehensive review describes the evolution of stimulant drug formulations used in the treatment of attention-deficit/hyperactivity disorder (ADHD). Emphasis is placed on the basic and clinical pharmacology of the dl-methylphenidate (MPH) transdermal system (MTS). METHODS The pharmacokinetic and pharmacodynamic literature pertaining to MPH and amphetamine enantiomers was reviewed in the context of ADHD therapy and MTS as a treatment option. RESULTS MTS incorporates MPH into an adhesive monolithic matrix, using the free base form of the drug to facilitate transdermal absorption. MTS technology minimizes contact dermatitis by eliminating to need for percutaneous penetration enhancers. After a lag time of approximately 2 h, plasma concentrations of the therapeutic d-MPH isomer become detectable, then continuously rise over the course of the recommended 9 h wear time. Concentrations of l-MPH typically attain 40-50% that of d-MPH (vs. 1-2% following oral MPH). Unauthorized MTS removal poses some misuse liability and over 50% of MTS drug content remains in the discarded system. CONCLUSIONS While liquid or chewable MPH formulations overcome potential swallowing difficulties, as do sprinkled once-daily extended-release (ER) MPH products, only MTS addresses swallowing difficulties while also offering a flexible individualized MPH exposure time in a once-daily MPH regimen.
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Affiliation(s)
- Kennerly S. Patrick
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA,Correspondence to: K. S. Patrick, 280 Calhoun St., QF221A, Medical University of South Carolina, Charleston, SC 29425−0742, USA. Tel: (843) 792−8429. Fax: (843) 792−1617. E-mail:
| | - Arthur B. Straughn
- Department of Pharmaceutical Sciences, University of Tennessee, Memphis, Tennessee, USA
| | - Jeb S. Perkins
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
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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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