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Hersey M, Tanda G. Modafinil, an atypical CNS stimulant? ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:287-326. [PMID: 38467484 DOI: 10.1016/bs.apha.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Modafinil is a central nervous system stimulant approved for the treatment of narcolepsy and sleep disorders. Due to its wide range of biochemical actions, modafinil has been explored for other potential therapeutic uses. Indeed, it has shown promise as a therapy for cognitive disfunction resulting from neurologic disorders like ADHD, and as a smart drug in non-medical settings. The mechanism(s) of actions underlying the therapeutic efficacy of this agent remains largely elusive. Modafinil is known to inhibit the dopamine transporter, thus decreasing dopamine reuptake following neuronal release, an effect shared by addictive psychostimulants. However, modafinil is unique in that only a few cases of dependence on this drug have been reported, as compared to other psychostimulants. Moreover, modafinil has been tested, with some success, as a potential therapeutic agent to combat psychostimulant and other substance use disorders. Modafinil has additional, but less understood, actions on other neurotransmitter systems (GABA, glutamate, serotonin, norepinephrine, etc.). These interactions, together with its ability to activate selected brain regions, are likely one of the keys to understand its unique pharmacology and therapeutic activity as a CNS stimulant. In this chapter, we outline the pharmacokinetics and pharmacodynamics of modafinil that suggest it has an "atypical" CNS stimulant profile. We also highlight the current approved and off label uses of modafinil, including its beneficial effects as a treatment for sleep disorders, cognitive functions, and substance use disorders.
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Affiliation(s)
- Melinda Hersey
- Medication Development Program, NIDA-IRP, NIH, Baltimore, MD, United States
| | - Gianluigi Tanda
- Medication Development Program, NIDA-IRP, NIH, Baltimore, MD, United States.
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Alam N, Choudhary K. Neurochemical Effects of Methylphenidate and Modafinil in Ameliorating Stress-Induced Cognitive Deficits. ACS Pharmacol Transl Sci 2023; 6:1357-1372. [PMID: 37854618 PMCID: PMC10580386 DOI: 10.1021/acsptsci.3c00077] [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: 04/07/2023] [Indexed: 10/20/2023]
Abstract
PURPOSE Chronic stressful situations result in altered monoaminergic activity of neurotransmitters, resulting in various conditions characterized by deficits in learning, memory and attention. Stimulant effects can be visualized in terms of increased cognitive abilities through enhancement of dopamine (DA) release. METHOD This study examined cognitive responses and brain DA and 5-hydroxytryptamine (5HT) levels after prolonged methylphenidate (MPH) and modafinil administration, to demonstrate their effect on stress-induced cognitive deficits in rats. Effects on cognition were evaluated by passive avoidance and water maze tests. Furthermore brain levels of DA, homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC), 5HT and 5-hydroxyindoleacetic acid (5HIAA) were analyzed by high-performance liquid chromatography coupled with electrochemical detection. RESULTS We found that both MPH and modafinil improved cognition in both restrained and unrestrained rats, as examined through water maze and passive avoidance tests. Furthermore, these substance were associated with increased brain DA and 5-HT levels. Notabily, we observed decrease in DOPAC and HVA levels, while 5-HIAA levels exhibited a slight increase. CONCLUSIONS The prevention of stress-induced cognitive deficits by MPH and modafinil could be elucidated through the interaction between 5HT and DA in regulating cognitive function.
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Affiliation(s)
- Nausheen Alam
- Federal Urdu University of Arts, Science
and Technology, Karachi 75300, Pakistan
| | - Kulsoom Choudhary
- Federal Urdu University of Arts, Science
and Technology, Karachi 75300, Pakistan
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Ngo Q, Plante DT. An Update on the Misuse and Abuse Potential of Pharmacological Treatments for Central Disorders of Hypersomnolence. CURRENT SLEEP MEDICINE REPORTS 2022. [DOI: 10.1007/s40675-022-00227-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yin F, Zhang J, Lu Y, Zhang Y, Liu J, Deji C, Qiao X, Gao K, Xu M, Lai J, Wang Y. Modafinil rescues repeated morphine-induced synaptic and behavioural impairments via activation of D1R-ERK-CREB pathway in medial prefrontal cortex. Addict Biol 2022; 27:e13103. [PMID: 34647651 DOI: 10.1111/adb.13103] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 06/19/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
Long-term opioid abuse causes a variety of long-lasting cognitive impairments such as attention, impulsivity and working memory. These cognitive impairments undermine behavioural treatment for drug abuse and lead to poor treatment retention and outcomes. Modafinil is a wake-promoting drug that shows potential in improving attention and memory in humans and animals. However, modafinil's effect on opioid-induced cognitive impairments remains unclear, and the underlying mechanism is poorly understood. This study showed that repeated morphine administration significantly impairs attention, increases impulsivity and reduces motivation to natural rewards in mice. Systemic modafinil treatment at low dose efficiently ameliorates morphine-induced attention dysfunction and improves motivation and working memory in mice. High dose of modafinil has adverse effects on impulsive action and attention. Local infusion of D1R antagonist SCH-23390 reverses the morphine-induced synaptic abnormalities and activation of the D1R-ERK-CREB pathway in medial prefrontal cortex (mPFC). This study demonstrated a protective effect of modafinil in mPFC neurons and offered a therapeutic potential for cognitive deficits in opioid abuse.
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Affiliation(s)
- Fangyuan Yin
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Jinyu Zhang
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Ye Lu
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Yulei Zhang
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Jincen Liu
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Cuola Deji
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Xiaomeng Qiao
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan, China
| | - Keqiang Gao
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Min Xu
- School of Pharmacy, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jianghua Lai
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Yunpeng Wang
- College of Forensic Science, Xi'an Jiaotong University, Xi'an, Shaanxi, China
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Hersey M, Bacon AK, Bailey LG, Coggiano MA, Newman AH, Leggio L, Tanda G. Psychostimulant Use Disorder, an Unmet Therapeutic Goal: Can Modafinil Narrow the Gap? Front Neurosci 2021; 15:656475. [PMID: 34121988 PMCID: PMC8187604 DOI: 10.3389/fnins.2021.656475] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/20/2021] [Indexed: 12/11/2022] Open
Abstract
The number of individuals affected by psychostimulant use disorder (PSUD) has increased rapidly over the last few decades resulting in economic, emotional, and physical burdens on our society. Further compounding this issue is the current lack of clinically approved medications to treat this disorder. The dopamine transporter (DAT) is a common target of psychostimulant actions related to their use and dependence, and the recent availability of atypical DAT inhibitors as a potential therapeutic option has garnered popularity in this research field. Modafinil (MOD), which is approved for clinical use for the treatment of narcolepsy and sleep disorders, blocks DAT just like commonly abused psychostimulants. However, preclinical and clinical studies have shown that it lacks the addictive properties (in both behavioral and neurochemical studies) associated with other abused DAT inhibitors. Clinical availability of MOD has facilitated its off-label use for several psychiatric disorders related to alteration of brain dopamine (DA) systems, including PSUD. In this review, we highlight clinical and preclinical research on MOD and its R-enantiomer, R-MOD, as potential medications for PSUD. Given the complexity of PSUD, we have also reported the effects of MOD on psychostimulant-induced appearance of several symptoms that could intensify the severity of the disease (i.e., sleep disorders and impairment of cognitive functions), besides the potential therapeutic effects of MOD on PSUD.
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Affiliation(s)
- Melinda Hersey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Amanda K. Bacon
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Lydia G. Bailey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Mark A. Coggiano
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Amy H. Newman
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Lorenzo Leggio
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
- Clinical Psychoneuroendo- crinology and Neuropsychopharmacology Section, Translational Addiction Medicine Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
- National Institute on Alcohol Abuse and Alcoholism, Division of Intramural Clinical and Biological Research, National Institutes of Health, Bethesda, MD, United States
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
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Tanda G, Hersey M, Hempel B, Xi ZX, Newman AH. Modafinil and its structural analogs as atypical dopamine uptake inhibitors and potential medications for psychostimulant use disorder. Curr Opin Pharmacol 2020; 56:13-21. [PMID: 32927246 DOI: 10.1016/j.coph.2020.07.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 12/20/2022]
Abstract
Pharmacotherapeutics for treatment of psychostimulant use disorder are still an unmet medical goal. Recently, off label use of modafinil (MOD), an approved medication for treatment of sleep disturbances, has been tested as a therapeutic for cocaine and methamphetamine use disorder. Positive results have been found in subjects dependent on psychostimulants without concurrent abuse of other substances. Novel structural analogs of MOD have been synthesized in the search for compounds with potentially broader therapeutic efficacy than the parent drug. In the present report we review their potential efficacy as treatments for psychostimulant abuse and dependence assessed in preclinical tests. Results from these preclinical proof of concept studies reveal that some modafinil analogs do not possess typical cocaine-like neurochemical and behavioral effects. Further, they might blunt the reinforcing effects of psychostimulants in animal models, suggesting their potential efficacy as pharmacotherapeutics for treatment of psychostimulant use disorders.
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Affiliation(s)
- Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, DHHS, 333 Cassell Drive, Baltimore, MD, 21224, USA.
| | - Melinda Hersey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, DHHS, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Briana Hempel
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, DHHS, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Zheng-Xiong Xi
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, DHHS, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Amy Hauck Newman
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, NIH, DHHS, 333 Cassell Drive, Baltimore, MD, 21224, USA
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Assi S, Khan I, Edwards A, Osselton D, Al-Obaidi H. On-spot quantification of modafinil in generic medicines purchased from the Internet using handheld Fourier transform-infrared, near-infrared and Raman spectroscopy. J Anal Sci Technol 2020. [DOI: 10.1186/s40543-020-00229-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
AbstractPoor quality medicines represent an expanding global public health threat facilitated by the Internet. A recent survey showed that one in five students have used modafinil to enhance learning ability mainly purchased from Internet sources. The aim of this work was to develop on-the-spot and simple methods for the quantification of modafinil in generic medicines using Fourier transform-infrared (FTIR), near-infrared (NIR) and Raman spectroscopy along with partial least square regression (PLSR). Modafinil tablets were measured in intact form using NIR and Raman and in powdered form using FTIR, NIR and Raman. Additionally, powder mixtures of crushed modafinil tablets and excipient(s) were prepared either by diluting the crushed tablets with excipient(s), or sequentially adding excipient(s) to the crushed tablets. Three PLSR models were constructed in MATLAB 2014a from powder mixtures and two from intact and powdered tablets. For FTIR and Raman spectroscopy, PLSR models based on tablets gave linear calibration curve with correlation coefficient (r2) values above 0.94 and a root mean square error of calibration (RMSEC) below 0.96% m/m. Conversely, the PLSR model based on powder sequential addition gave the highest accuracy using the NIR spectra (r2 = 0.99, RMSEC = 1.15% m/m). The latter model showed accuracy in predicting the concentration of the active pharmaceutical ingredient in modafinil generic medicines proving their authenticity. The overall results showed that the combination of the three spectroscopic methods with PLSR offered a rapid technique for authenticating generic modafinil medicines.
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Sousa A, Dinis-Oliveira RJ. Pharmacokinetic and pharmacodynamic of the cognitive enhancer modafinil: Relevant clinical and forensic aspects. Subst Abus 2020; 41:155-173. [PMID: 31951804 DOI: 10.1080/08897077.2019.1700584] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Modafinil is a nonamphetamine nootropic drug with an increasingly therapeutic interest due to its different sites of action and behavioral effects in comparison to cocaine or amphetamine. A review of modafinil (and of its prodrug adrafinil and its R-enantiomer armodafinil) chemical, pharmacokinetic, pharmacodynamic, toxicological, clinical and forensic aspects was performed, aiming to better understand possible health problems associated to its unconscious and unruled use. Modafinil is a racemate metabolized mainly in the liver into its inactive acid and sulfone metabolites, which undergo primarily renal excretion. Although not fully clarified, major effects seem to be associated to inhibition of dopamine reuptake and modulation of several other neurochemical pathways, namely noradrenergic, serotoninergic, orexinergic, histaminergic, glutamatergic and GABAergic. Due its wake-promoting effects, modafinil is used for the treatment of daily sleepiness associated to narcolepsy, obstructive sleep apnea and shift work sleep disorder. Its psychotropic and cognitive effects are also attractive in several other pathologies and conditions that affect sleep structure, induce fatigue and lethargy, and impair cognitive abilities. Additionally, in health subjects, including students, modafinil is being used off-label to overcome sleepiness, increase concentration and improve cognitive potential. The most common adverse effects associated to modafinil intake are headache, insomnia, anxiety, diarrhea, dry mouth and raise in blood pressure and heart rate. Infrequently, severe dermatologic effects in children, including maculopapular and morbilliform rash, erythema multiforme and Stevens-Johnson Syndrome have been reported. Intoxication and dependence associated to modafinil are uncommon. Further research on effects and health implications of modafinil and its analogs is steel needed to create evidence-based policies.
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Affiliation(s)
- Ana Sousa
- Department of Public Health and Forensic Sciences, and Medical Education, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Ricardo Jorge Dinis-Oliveira
- Department of Public Health and Forensic Sciences, and Medical Education, Faculty of Medicine, University of Porto, Porto, Portugal.,IINFACTS - Institute of Research and Advanced Training in Health Sciences and Technologies, Department of Sciences, University Institute of Health Sciences (IUCS), CESPU, CRL, Gandra, Portugal.,UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
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Reinert JP, Dunn RL. Management of overdoses of loperamide, gabapentin, and modafinil: a literature review. Expert Rev Clin Pharmacol 2019; 12:901-908. [DOI: 10.1080/17512433.2019.1657830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Justin P. Reinert
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, TX, USA
| | - Rebecca L. Dunn
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, TX, USA
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Keighron JD, Giancola JB, Shaffer RJ, DeMarco EM, Coggiano MA, Slack RD, Hauck Newman A, Tanda G. Distinct effects of (R)-modafinil and its (R)- and (S)-fluoro-analogs on mesolimbic extracellular dopamine assessed by voltammetry and microdialysis in rats. Eur J Neurosci 2019; 50:2045-2053. [PMID: 30402972 PMCID: PMC8294075 DOI: 10.1111/ejn.14256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 02/06/2023]
Abstract
Psychostimulant use disorders remain an unabated public health concern worldwide, but no FDA approved medications are currently available for treatment. Modafinil (MOD), like cocaine, is a dopamine reuptake inhibitor and one of the few drugs evaluated in clinical trials that has shown promise for the treatment of cocaine or methamphetamine use disorders in some patient subpopulations. Recent structure-activity relationship and preclinical studies on a series of MOD analogs have provided insight into modifications of its chemical structure that may lead to advancements in clinical efficacy. Here, we have tested the effects of the clinically available (R)-enantiomer of MOD on extracellular dopamine levels in the nucleus accumbens shell, a mesolimbic dopaminergic projection field that plays significant roles in various aspects of psychostimulant use disorders, measured in vivo by fast-scan cyclic voltammetry and by microdialysis in Sprague-Dawley rats. We have compared these results with those obtained under identical experimental conditions with two novel and enantiopure bis(F) analogs of MOD, JBG1-048 and JBG1-049. The results show that (R)-modafinil (R-MOD), JBG1-048, and JBG1-049, when administered intravenously with cumulative drug-doses, will block the dopamine transporter and reduce the clearance rate of dopamine, increasing its extracellular levels. Differences among the compounds in their maximum stimulation of dopamine levels, and in their time course of effects were also observed. These data highlight the mechanistic underpinnings of R-MOD and its bis(F) analogs as pharmacological tools to guide the discovery of novel medications to treat psychostimulant use disorders.
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Affiliation(s)
- Jacqueline D. Keighron
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - JoLynn B. Giancola
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Rachel J. Shaffer
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Emily M. DeMarco
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Mark A. Coggiano
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Rachel D. Slack
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Amy Hauck Newman
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
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Zanettini C, Scaglione A, Keighron JD, Giancola JB, Lin SC, Newman AH, Tanda G. Pharmacological classification of centrally acting drugs using EEG in freely moving rats: an old tool to identify new atypical dopamine uptake inhibitors. Neuropharmacology 2018; 161:107446. [PMID: 30481526 DOI: 10.1016/j.neuropharm.2018.11.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/05/2018] [Accepted: 11/23/2018] [Indexed: 10/27/2022]
Abstract
Atypical dopamine uptake inhibitors (DUIs) bind to the dopamine transporter and inhibit the reuptake of dopamine but have lower abuse potential than psychostimulants. Several atypical DUIs can block abuse-related effects of cocaine and methamphetamine, thus making them potential medication candidates for psychostimulant use disorders. The aim of the current study is to establish an in-vivo assay using EEG for the rapid identification of atypical DUIs with potential for medication development. The typical DUIs cocaine and methylphenidate dose-dependently decreased the power of the alpha, beta, and gamma bands. The atypical DUI modafinil and its F-analog, JBG1-049, decreased the power of beta, but in contrast to cocaine, none of the other frequency bands, while JHW007 did not significantly alter the EEG spectrum. The mu-opioid receptor agonists heroin and morphine dose-dependently decreased the power of gamma and increased power of the other bands. The effect of morphine on EEG power bands was antagonized by naltrexone. The NMDA receptor antagonist ketamine increased the power of all frequency bands. Therefore, typical and atypical DUIs and drugs of other classes differentially affected EEG spectra, showing distinctive features in the magnitude and direction of their effects on EEG. Comparative analysis of the effects of test drugs on EEG indicates a potential atypical profile of JBG1-049 with similar potency and effectiveness to its parent compound modafinil. These data suggest that EEG can be used to rapidly screen compounds for potential activity at specific pharmacological targets and provide valuable information for guiding the early stages of drug development. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Claudio Zanettini
- Medication Development Program, Molecular Targets and Medications Discovery Branch, NIDA-IRP, NIH/DHHS, Baltimore, MD, USA.
| | - Alessandro Scaglione
- Neural Circuits and Cognition Unit, Laboratory of Behavioral Neuroscience, NIA-IRP, NIH/DHHS, Baltimore, MD, USA
| | - Jacqueline D Keighron
- Medication Development Program, Molecular Targets and Medications Discovery Branch, NIDA-IRP, NIH/DHHS, Baltimore, MD, USA
| | - JoLynn B Giancola
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, NIDA-IRP, NIH/DHHS, Baltimore, MD, USA
| | - Shih-Chieh Lin
- Neural Circuits and Cognition Unit, Laboratory of Behavioral Neuroscience, NIA-IRP, NIH/DHHS, Baltimore, MD, USA
| | - Amy H Newman
- Medication Development Program, Molecular Targets and Medications Discovery Branch, NIDA-IRP, NIH/DHHS, Baltimore, MD, USA; Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, NIDA-IRP, NIH/DHHS, Baltimore, MD, USA
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medications Discovery Branch, NIDA-IRP, NIH/DHHS, Baltimore, MD, USA
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Oral modafinil facilitates intracranial self-stimulation in rats: comparison with methylphenidate. Behav Pharmacol 2018; 28:318-322. [PMID: 28125506 DOI: 10.1097/fbp.0000000000000288] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Modafinil is a low-potency inhibitor of dopamine transporters (DAT) approved clinically to promote wakefulness. In most procedures used for abuse-liability assessment, modafinil produces effects similar to those of abused DAT inhibitors such as cocaine and methylphenidate, although modafinil often shows lower effectiveness. However, modafinil has failed to maintain drug self-administration or produce conditioned place preferences in rats. The low potency and poor solubility of modafinil complicate its delivery by parenteral routes of administration commonly used in rats, and this may contribute toward negative results. This study evaluated the effects of orally administered modafinil in rats using an assay of intracranial self-stimulation (ICSS) that has been used to examine the effects of other DAT inhibitors. Adult male Sprague-Dawley rats equipped with electrodes in the medial forebrain bundle responded for pulses of brain stimulation that varied across a range of frequencies (158-56 Hz) during daily behavioral sessions. Modafinil (20-600 mg/kg, orally) and methylphenidate (1.0-10 mg/kg, intraperitoneally; 3.2-32 mg/kg, orally) produced dose-dependent and time-dependent facilitation of ICSS, an effect produced by abused DAT inhibitors and other classes of abused drugs. These results are in agreement with other evidence for stimulant-like abuse liability of modafinil and show the sensitivity of ICSS to orally administered drug.
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Avelar AJ, Cao J, Newman AH, Beckstead MJ. Atypical dopamine transporter inhibitors R-modafinil and JHW 007 differentially affect D2 autoreceptor neurotransmission and the firing rate of midbrain dopamine neurons. Neuropharmacology 2017; 123:410-419. [PMID: 28625719 PMCID: PMC5546153 DOI: 10.1016/j.neuropharm.2017.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/17/2017] [Accepted: 06/14/2017] [Indexed: 12/12/2022]
Abstract
Abuse of psychostimulants like cocaine that inhibit dopamine (DA) reuptake through the dopamine transporter (DAT) represents a major public health issue, however FDA-approved pharmacotherapies have yet to be developed. Recently a class of ligands termed "atypical DAT inhibitors" has gained attention due to their range of effectiveness in increasing extracellular DA levels without demonstrating significant abuse liability. These compounds not only hold promise as therapeutic agents to treat stimulant use disorders but also as experimental tools to improve our understanding of DAT function. Here we used patch clamp electrophysiology in mouse brain slices to explore the effects of two atypical DAT inhibitors (R-modafinil and JHW 007) on the physiology of single DA neurons in the substantia nigra and ventral tegmental area. Despite their commonalities of being DAT inhibitors that lack cocaine-like behavioral profiles, these compounds exhibited surprisingly divergent cellular effects. Similar to cocaine, R-modafinil slowed DA neuron firing in a D2 receptor-dependent manner and rapidly enhanced the amplitude and duration of D2 receptor-mediated currents in the midbrain. In contrast, JHW 007 exhibited little effect on firing, slow DAT blockade, and an unexpected inhibition of D2 receptor-mediated currents that may be due to direct D2 receptor antagonism. Furthermore, pretreatment with JHW 007 blunted the cellular effects of cocaine, suggesting that it may be valuable to investigate similar DAT inhibitors as potential therapeutic agents. Further exploration of these and other atypical DAT inhibitors may reveal important cellular effects of compounds that will have potential as pharmacotherapies for treating cocaine use disorders.
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Affiliation(s)
- Alicia J Avelar
- Department of Cellular and Integrative Physiology, UT Health Science Center, San Antonio, TX, 78229, USA.
| | - Jianjing Cao
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA.
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, 21224, USA.
| | - Michael J Beckstead
- Department of Cellular and Integrative Physiology, UT Health Science Center, San Antonio, TX, 78229, USA.
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14
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Wuo-Silva R, Fukushiro DF, Hollais AW, Santos-Baldaia R, Mári-Kawamoto E, Berro LF, Yokoyama TS, Lopes-Silva LB, Bizerra CS, Procópio-Souza R, Hashiguchi D, Figueiredo LA, Costa JL, Frussa-Filho R, Longo BM. Modafinil Induces Rapid-Onset Behavioral Sensitization and Cross-Sensitization with Cocaine in Mice: Implications for the Addictive Potential of Modafinil. Front Pharmacol 2016; 7:420. [PMID: 27872594 PMCID: PMC5097917 DOI: 10.3389/fphar.2016.00420] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/21/2016] [Indexed: 02/06/2023] Open
Abstract
There is substantial controversy about the addictive potential of modafinil, a wake-promoting drug used to treat narcolepsy, proposed as pharmacotherapy for cocaine abuse, and used indiscriminately by healthy individuals due to its positive effects on arousal and cognition. The rapid-onset type of behavioral sensitization (i.e., a type of sensitization that develops within a few hours from the drug priming administration) has been emerged as a valuable tool to study binge-like patterns of drug abuse and the neuroplastic changes that occur quickly after drug administration that ultimately lead to drug abuse. Our aim was to investigate the possible development of rapid-onset behavioral sensitization to modafinil and bidirectional rapid-onset cross-sensitization with cocaine in male Swiss mice. A priming injection of a high dose of modafinil (64 mg/kg) induced rapid-onset behavioral sensitization to challenge injections of modafinil at the doses of 16, 32, and 64 mg/kg, administered 4 h later. Furthermore, rapid-onset cross-sensitization was developed between modafinil and cocaine (64 mg/kg modafinil and 20 mg/kg cocaine), in a bidirectional way. These results were not due to residual levels of modafinil as the behavioral effects of the priming injection of modafinil were no longer present and modafinil plasma concentration was reduced at 4 h post-administration. Taken together, the present findings provide preclinical evidence that modafinil can be reinforcing per se and can enhance the reinforcing effects of stimulants like cocaine within hours after administration.
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Affiliation(s)
- Raphael Wuo-Silva
- Laboratory of Neurophysiology, Department of Physiology, Universidade Federal de São PauloSão Paulo, Brazil; Department of Pharmacology, Universidade Federal de São PauloSão Paulo, Brazil
| | - Daniela F Fukushiro
- Department of Pharmacology, Universidade Federal de São Paulo São Paulo, Brazil
| | - André W Hollais
- Department of Pharmacology, Universidade Federal de São Paulo São Paulo, Brazil
| | | | - Elisa Mári-Kawamoto
- Department of Pharmacology, Universidade Federal de São Paulo São Paulo, Brazil
| | - Laís F Berro
- Department of Psychobiology, Universidade Federal de São Paulo São Paulo, Brazil
| | - Thaís S Yokoyama
- Laboratory of Neurophysiology, Department of Physiology, Universidade Federal de São Paulo São Paulo, Brazil
| | | | - Carolina S Bizerra
- Department of Pharmacology, Universidade Federal de São Paulo São Paulo, Brazil
| | | | - Debora Hashiguchi
- Laboratory of Neurophysiology, Department of Physiology, Universidade Federal de São Paulo São Paulo, Brazil
| | - Lilian A Figueiredo
- Laboratory of Neurophysiology, Department of Physiology, Universidade Federal de São Paulo São Paulo, Brazil
| | - Jose L Costa
- Faculty of Pharmaceutical Sciences, Universidade Estadual de Campinas Campinas, Brazil
| | | | - Beatriz M Longo
- Laboratory of Neurophysiology, Department of Physiology, Universidade Federal de São Paulo São Paulo, Brazil
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15
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Mereu M, Chun LE, Prisinzano TE, Newman AH, Katz JL, Tanda G. The unique psychostimulant profile of (±)-modafinil: investigation of behavioral and neurochemical effects in mice. Eur J Neurosci 2016; 45:167-174. [PMID: 27545285 DOI: 10.1111/ejn.13376] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/08/2016] [Accepted: 08/18/2016] [Indexed: 11/29/2022]
Abstract
Blockade of dopamine (DA) reuptake via the dopamine transporter (DAT) is a primary mechanism identified as underlying the therapeutic actions of (±)-modafinil (modafinil) and its R-enantiomer, armodafinil. Herein, we explored the neurochemical and behavioral actions of modafinil to better characterize its psychostimulant profile. Swiss-Webster mice were implanted with microdialysis probes in the nucleus accumbens shell (NAS) or core (NAC) to evaluate changes in DA levels related to acute reinforcing actions of drugs of abuse. Additionally, subjective effects were studied in mice trained to discriminate 10 mg/kg cocaine (i.p.) from saline. Modafinil (17-300 mg/kg, i.p.) significantly increased NAS and NAC DA levels that at the highest doses reached ~300% at 1 h, and lasted > 6 h in duration. These elevated DA levels did not show statistically significant regional differences between the NAS and NAC. Modafinil produced cocaine-like subjective effects at 56-100 mg/kg when administered at 5 and 60 min before the start of the session, and enhanced cocaine effects when the two were administered in combination. Despite sharing subjective effects with cocaine, modafinil's psychostimulant profile was unique compared to that of cocaine and like compounds. Modafinil had lower potency and efficacy than cocaine in stimulating NAS DA. In addition, the cocaine-like subjective effects of modafinil were obtained at lower doses and earlier onset times than expected based on its dopaminergic effects. These studies suggest that although inhibition of DA reuptake may be a primary mechanism underlying modafinil's therapeutic actions, non DA-dependent actions may be playing a role in its psychostimulant profile.
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Affiliation(s)
- Maddalena Mereu
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Lauren E Chun
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Thomas E Prisinzano
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA
| | - Amy H Newman
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA.,Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Jonathan L Katz
- Psychobiology Section, Molecular Neuropsychiatry Research Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA
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16
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De Ron P, Dremier S, Winlow P, Jenkins A, Hanon E, Nogueira da Costa A. Correlating behaviour and gene expression endpoints in the dopaminergic system after modafinil administration in mouse. Eur Neuropsychopharmacol 2016; 26:729-40. [PMID: 26875113 DOI: 10.1016/j.euroneuro.2016.01.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 01/18/2016] [Accepted: 01/25/2016] [Indexed: 10/22/2022]
Abstract
The mechanisms of action of modafinil continue to be poorly characterised and its potential for abuse in preclinical models remains controverted. The aim of this study was to further elucidate the mechanism of action of modafinil, through a potential behavioural and molecular association in the mouse. A conditioned place preference (CPP) paradigm was implemented to investigate the rewarding properties of modafinil. Whole genome expression and qRT-PCR analysis were performed on the ventral tegmental area (VTA), nucleus accumbens (NAC) and prefrontal cortex (PFC) of modafinil-treated and control animals. Modafinil administration (65 mg/kg) induced an increase in locomotor activity, an increase in the change of preference for the drug paired side after a conditioning period as well as changes to gene expression profiles in the VTA (120 genes), NAC (23 genes) and PFC (19 genes). A molecular signature consisting of twelve up-regulated genes was identified as common to the three brain regions. Multiple linear correlation analysis showed a strong correlation (R(2)>0.70) between the behavioural and molecular endpoints in the three brain regions. We show that modafinil had a concomitant effect on CPP, locomotor activity, and up-regulation of interferon-γ (IFN-γ) regulated genes (Gbp2, Gbp3, Gbp10, Cd274, Igtp), while correlating the latter set of genes with behaviour changes evaluated through the CPP. A potential association can be proposed based on the dysregulation of p47 family genes and Gbp family of IFN-γ induced GTPases. In conclusion, these findings suggest a link between the behavioural and molecular events in the context of modafinil administration.
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Affiliation(s)
- P De Ron
- Non-Clinical Development, UCB Biopharma SPRL, Belgium
| | - S Dremier
- Non-Clinical Development, UCB Biopharma SPRL, Belgium
| | - P Winlow
- Non-Clinical Development, UCB Biopharma SPRL, Belgium
| | - A Jenkins
- Non-Clinical Development, UCB Biopharma SPRL, Belgium
| | - E Hanon
- CNS Research, UCB Biopharma SPRL, Belgium
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Burrows BT, Watterson LR, Johnson MA, Olive MF. Effects of modafinil and R-modafinil on brain stimulation reward thresholds: implications for their use in the treatment of psychostimulant dependence. ACTA ACUST UNITED AC 2015; 4. [PMID: 27284492 DOI: 10.4303/jdar/235958] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Modafinil and its enantiomer R-modafinil are approved for the treatment of various sleep disorders, and may also be efficacious in the treatment of psychostimulant abuse. However, the ability of modafinil and R-modafinil to alter brain reward function has not yet been assessed. PURPOSE This study assessed the effects of modafinil and R-modafinil on brain reward function using the intracranial self-stimulation (ICSS) paradigm. STUDY DESIGN Male Sprague-Dawley rats were trained to respond for ICSS using current-intensity threshold determination procedures. Changes in ICSS thresholds were then assessed following administration of modafinil and R-modafinil (50, 100, and 150 mg/kg), or cocaine (2.5 - 20 mg/kg) as a positive control. RESULTS ICSS thresholds were reduced by modafinil at the 150 mg/kg dose, as well as by cocaine at the 10 and 20 mg/kg doses. R-modafinil only produced non-significant trends towards reducing ICSS thresholds. CONCLUSION Modafinil and R-modafinil have limited effects on brain reward function in otherwise drug-naïve subjects. Additional assessments of these effects in the context of psychostimulant dependence are needed.
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Affiliation(s)
- Brian T Burrows
- Arizona State University, Department of Psychology, Behavioral Neuroscience Area, Tempe, AZ, USA
| | - Lucas R Watterson
- Arizona State University, Department of Psychology, Behavioral Neuroscience Area, Tempe, AZ, USA
| | - Meagan A Johnson
- Arizona State University, Department of Psychology, Behavioral Neuroscience Area, Tempe, AZ, USA
| | - M Foster Olive
- Arizona State University, Department of Psychology, Behavioral Neuroscience Area, Tempe, AZ, USA; Arizona State University, Interdisciplinary Graduate Program in Neuroscience, Tempe, AZ, USA
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18
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Dopaminergic mediation of the discriminative stimulus functions of modafinil in rats. Psychopharmacology (Berl) 2015; 232:4411-9. [PMID: 26374456 DOI: 10.1007/s00213-015-4065-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 08/30/2015] [Indexed: 10/23/2022]
Abstract
RATIONALE Modafinil is a wake-promoting drug with FDA approval for the treatment of excessive daytime sleepiness that has been prescribed for ADHD and recently assessed as a potential treatment for psychostimulant dependence. Previous research indicates that modafinil modestly increases locomotor activity and produces similar discriminative stimulus effects to psychostimulants in rodents, although the subjective effects of modafinil are reportedly distinct from those of cocaine or amphetamine in humans with a history of psychostimulant abuse. OBJECTIVES The current study employed drug discrimination procedures in rats to examine the pharmacological actions contributing to modafinil's discriminative stimulus functions. METHODS Eight male Sprague-Dawley rats were trained to discriminate intragastric administration of 256 mg/kg modafinil from vehicle (5% arabic gum) under a FR 20 schedule of food reinforcement. Substitution tests were conducted with various dopaminergic agents (d-amphetamine, cocaine, PNU-91356A, GBR 12909, methylphenidate) and nondopaminergic agents (nicotine, ethanol). Antagonist tests were conducted with the selective D1 antagonist, SCH 39166, and the nonselective D2 antagonist, haloperidol. RESULTS Rats trained to discriminate modafinil displayed complete stimulus generalization to cocaine, methylphenidate, and GBR 12909 and the discrimination was completely blocked by both SCH 39166 and haloperidol. Evidence for significant partial substitution was obtained with d-amphetamine, PNU-91356A, and nicotine. CONCLUSIONS Results strongly support the role of dopaminergic mechanisms in the discriminative stimulus functions of modafinil, although further evaluation regarding the contribution of other neurotransmitter systems to these effects should be continued. The findings are discussed in light of clinical research efforts with modafinil as a treatment for psychostimulant dependence.
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19
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Bernardi RE, Broccoli L, Spanagel R, Hansson AC. Sex differences in dopamine binding and modafinil conditioned place preference in mice. Drug Alcohol Depend 2015; 155:37-44. [PMID: 26342627 DOI: 10.1016/j.drugalcdep.2015.08.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 08/21/2015] [Accepted: 08/21/2015] [Indexed: 01/06/2023]
Abstract
BACKGROUND Studies in humans and rodents have demonstrated under certain conditions some reinforcing properties of modafinil, a drug being examined clinically for its potential to treat psychostimulant abuse. However, the majority of rodent studies examining the abuse potential of modafinil have used high doses that may not be clinically relevant. In fact, recent work has indicated that doses similar to those administered to humans are not reinforcing in mice. METHODS The current study examined sex differences in the ability of low-dose modafinil (0.75mg/kg, IP) to induce a conditioned place preference in mice, and assessed sex-dependent alterations in dopamine D1, D2 and DAT binding sites in reward-related regions in naïve and modafinil-treated mice. RESULTS Low-dose modafinil failed to induce a conditioned place preference in male mice, while female mice demonstrated a significant modafinil place preference. Several dopamine binding differences were also detected in naïve and modafinil-treated mice, including sex differences in D1 and D2 availability in reward-related regions, and are discussed in relation to sex-dependent differences in the reinforcing effects of modafinil and psychostimulants in general. CONCLUSIONS These findings implicate sex differences in the reinforcing properties of modafinil in mice, and indicate that clinical evaluation of the sex dependence of the reinforcing properties of modafinil in humans is warranted.
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Affiliation(s)
- Rick E Bernardi
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, J5, 68159, Mannheim, Germany.
| | - Laura Broccoli
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, J5, 68159, Mannheim, Germany
| | - Rainer Spanagel
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, J5, 68159, Mannheim, Germany
| | - Anita C Hansson
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, J5, 68159, Mannheim, Germany
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Wang XF, Bi GH, He Y, Yang HJ, Gao JT, Okunola-Bakare OM, Slack RD, Gardner EL, Xi ZX, Newman AH. R-modafinil attenuates nicotine-taking and nicotine-seeking behavior in alcohol-preferring rats. Neuropsychopharmacology 2015; 40:1762-71. [PMID: 25613829 PMCID: PMC4915260 DOI: 10.1038/npp.2015.24] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 01/01/2015] [Accepted: 01/12/2015] [Indexed: 12/20/2022]
Abstract
(±)-Modafinil (MOD) is used clinically for the treatment of sleep disorders and has been investigated as a potential medication for the treatment of psychostimulant addiction. However, the therapeutic efficacy of (±)-MOD for addiction is inconclusive. Herein we used animal models of self-administration and in vivo microdialysis to study the pharmacological actions of R-modafinil (R-MOD) and S-modafinil (S-MOD) on nicotine-taking and nicotine-seeking behavior, and mechanisms underlying such actions. We found that R-MOD is more potent and effective than S-MOD in attenuating nicotine self-administration in Long-Evans rats. As Long-Evans rats did not show a robust reinstatement response to nicotine, we used alcohol-preferring rats (P-rats) that display much higher reinstatement responses to nicotine than Long-Evans rats. We found that R-MOD significantly inhibited intravenous nicotine self-administration, nicotine-induced reinstatement, and nicotine-associated cue-induced drug-seeking behavior in P-rats. R-MOD alone neither sustained self-administration in P-rats previously self-administering nicotine nor reinstated extinguished nicotine-seeking behavior. The in vivo brain microdialysis assays demonstrated that R-MOD alone produced a slow-onset moderate increase in extracellular DA. Pretreatment with R-MOD dose-dependently blocked nicotine-induced dopamine (DA) release in the nucleus accumbens (NAc) in both naive and nicotine self-administrating rats, suggesting a DA-dependent mechanism underlying mitigation of nicotine's effects. In conclusion, the present findings support further investigation of R-MOD for treatment of nicotine dependence in humans.
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Affiliation(s)
- Xiao-Fei Wang
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Guo-Hua Bi
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Yi He
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Hong-Ju Yang
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Jun-Tao Gao
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Oluyomi M Okunola-Bakare
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Rachel D Slack
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Eliot L Gardner
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Zheng-Xiong Xi
- Neuropsychopharmacology Section, Molecular Target and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA,Neuropsychopharmacology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA, Tel: +1 443 740 2517, Fax: +1 443 740 2781, E-mail:
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA,Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA, Tel: +1 443 740 2887, Fax: +1 443 740 2111, E-mail:
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Abstract
Many patients with major depressive disorder (MDD) only partially respond, and some have no clinically meaningful response, to current widely used antidepressant drugs. Due to the purported role of dopamine in the pathophysiology of depression, triple-reuptake inhibitors (TRIs) that simultaneously inhibit serotonin (5-HT), norepinephrine (NE) and dopamine reuptake could be a useful addition to the armamentarium of treatments for MDD. A TRI should more effectively activate mesolimbic dopamine-related reward-networks, restore positive mood and reduce potent 5-HT reuptake blockade associated "hypodopaminergic" adverse effects of decreased libido, weight gain and "blunting" of emotions. On the other hand, dopaminergic effects raise concern over abuse liability and TRIs may have many of the cardiovascular effects associated with NET inhibition. Several clinical development programs for potential TRI antidepressants have failed to demonstrate significantly greater efficacy than placebo or standard of care. Successful late-stage clinical development of a TRI is more likely if experimental research studies in the target population of depressed patients have demonstrated target engagement that differentially and dose-dependently improves assessments of reward-network dysfunction relative to existing antidepressants. TRI treatment could be individualized on the basis of predictive markers such as the burden of decreased positive mood symptoms and/or neuroimaging evidence of reward network dysfunction. This review focuses on how the next generation of monoamine-based treatments could be efficiently developed to address unmet medical need in MDD.
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Reith ME, Blough BE, Hong WC, Jones KT, Schmitt KC, Baumann MH, Partilla JS, Rothman RB, Katz JL. Behavioral, biological, and chemical perspectives on atypical agents targeting the dopamine transporter. Drug Alcohol Depend 2015; 147:1-19. [PMID: 25548026 PMCID: PMC4297708 DOI: 10.1016/j.drugalcdep.2014.12.005] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 12/04/2014] [Accepted: 12/04/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Treatment of stimulant-use disorders remains a formidable challenge, and the dopamine transporter (DAT) remains a potential target for antagonist or agonist-like substitution therapies. METHODS This review focuses on DAT ligands, such as benztropine, GBR 12909, modafinil, and DAT substrates derived from phenethylamine or cathinone that have atypical DAT-inhibitor effects, either in vitro or in vivo. The compounds are described from a molecular mechanistic, behavioral, and medicinal-chemical perspective. RESULTS Possible mechanisms for atypicality at the molecular level can be deduced from the conformational cycle for substrate translocation. For each conformation, a crystal structure of a bacterial homolog is available, with a possible role of cholesterol, which is also present in the crystal of Drosophila DAT. Although there is a direct relationship between behavioral potencies of most DAT inhibitors and their DAT affinities, a number of compounds bind to the DAT and inhibit dopamine uptake but do not share cocaine-like effects. Such atypical behavior, depending on the compound, may be related to slow DAT association, combined sigma-receptor actions, or bias for cytosol-facing DAT. Some structures are sterically small enough to serve as DAT substrates but large enough to also inhibit transport. Such compounds may display partial DA releasing effects, and may be combined with release or uptake inhibition at other monoamine transporters. CONCLUSIONS Mechanisms of atypical DAT inhibitors may serve as targets for the development of treatments for stimulant abuse. These mechanisms are novel and their further exploration may produce compounds with unique therapeutic potential as treatments for stimulant abuse.
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Affiliation(s)
- Maarten E.A. Reith
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA,Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA,Corresponding author: Maarten E.A. Reith, Department of Psychiatry, Alexandria Center of Life Sciences, New York University School of Medicine, 450 E 29th Street, Room 803, New York, NY 10016. Tel.: 212 - 263 8267; Fax: 212 – 263 8183;
| | - Bruce E. Blough
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC 27709, USA
| | - Weimin C. Hong
- Psychobiology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Kymry T. Jones
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA
| | - Kyle C. Schmitt
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016, USA
| | - Michael H. Baumann
- Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - John S. Partilla
- Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Richard B. Rothman
- Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jonathan L. Katz
- Psychobiology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Uguen M, Perrin D, Belliard S, Ligneau X, Beardsley PM, Lecomte JM, Schwartz JC. Preclinical evaluation of the abuse potential of Pitolisant, a histamine H₃ receptor inverse agonist/antagonist compared with Modafinil. Br J Pharmacol 2014; 169:632-44. [PMID: 23472741 DOI: 10.1111/bph.12149] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/15/2012] [Accepted: 01/01/2013] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Pitolisant, a histamine H₃ receptor inverse agonist/antagonist is currently under Phase III clinical trials for treatment of excessive daytime sleepiness namely in narcoleptic patients. Its drug abuse potential was investigated using in vivo models in rodents and monkeys and compared with those of Modafinil, a psychostimulant currently used in the same indications. EXPERIMENTAL APPROACH Effects of Pitolisant on dopamine release in the nucleus accumbens, on spontaneous and cocaine-induced locomotion, locomotor sensitization were monitored. It was also tested in three standard drug abuse tests i.e. conditioned place preference in rats, self-administration in monkeys and cocaine discrimination in mice as well as in a physical dependence model. KEY RESULTS Pitolisant did not elicit any significant changes in dopaminergic indices in rat nucleus accumbens whereas Modafinil increased dopamine release. In rodents, Pitolisant was without any effect on locomotion and reduced the cocaine-induced hyperlocomotion. In addition, no locomotor sensitization and no conditioned hyperlocomotion were evidenced with this compound in rats whereas significant effects were elicited by Modafinil. Finally, Pitolisant was devoid of any significant effects in the three standard drug abuse tests (including self-administration in monkeys) and in the physical dependence model. CONCLUSIONS AND IMPLICATIONS No potential drug abuse liability for Pitolisant was evidenced in various in vivo rodent and primate models, whereas the same does not seem so clear in the case of Modafinil.
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Affiliation(s)
- M Uguen
- Bioprojet-Biotech, Saint Grégoire Cedex, France
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Stoops WW, Rush CR. Agonist replacement for stimulant dependence: a review of clinical research. Curr Pharm Des 2014; 19:7026-35. [PMID: 23574440 DOI: 10.2174/138161281940131209142843] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/04/2013] [Indexed: 11/22/2022]
Abstract
Stimulant use disorders are an unrelenting public health concern worldwide. Agonist replacement therapy is among the most effective strategies for managing substance use disorders including nicotine and opioid dependence. The present paper reviewed clinical data from human laboratory self-administration studies and clinical trials to determine whether agonist replacement therapy is a viable strategy for managing cocaine and/or amphetamine use disorders. The extant literature suggests that agonist replacement therapy may be effective for managing stimulant use disorders, however, the clinical selection of an agonist replacement medication likely needs to be based on the pharmacological mechanism of the medication and the stimulant abused by patients. Specifically, dopamine releasers appear most effective for reducing cocaine use whereas dopamine reuptake inhibitors appear most effective for reducing amphetamine use.
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Affiliation(s)
- William W Stoops
- Department of Behavioral Science, University of Kentucky Medical Center, Lexington, KY 40536- 0086.
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Funayama T, Ikeda Y, Tateno A, Takahashi H, Okubo Y, Fukayama H, Suzuki H. Modafinil augments brain activation associated with reward anticipation in the nucleus accumbens. Psychopharmacology (Berl) 2014; 231:3217-28. [PMID: 24682502 DOI: 10.1007/s00213-014-3499-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 02/08/2014] [Indexed: 10/25/2022]
Abstract
RATIONALE The nucleus accumbens (NAc) works as a key brain structure of the reward system, in which reward-related neural activity is well correlated with dopamine release from mesolimbic dopaminergic neurons. OBJECTIVES Since modafinil can modulate dopaminergic transmission through re-uptake inhibition of dopamine, we investigated whether modafinil affects the reward-related brain activity in the NAc in healthy subjects. METHODS Twenty healthy participants underwent two series of functional magnetic resonance imaging while performing monetary incentive delay task in which they were cued to anticipate and respond to a rapidly presented target to gain or avoid losing varying amounts of money, under modafinil or placebo condition. Blood oxygenation-level dependent (BOLD) activation signals during gain and loss anticipations were analyzed in the NAc as an a priori region of interest as well as the whole brain. RESULTS Modafinil significantly changed subjective feelings toward positive ones. The activation of BOLD signals was observed during gain anticipation under the placebo and modafinil conditions in the left and bilateral NAc, respectively. The modafinil condition showed significantly higher BOLD signal change at the highest gain (+¥500) cue compared to the placebo condition. CONCLUSIONS The present study showed that modafinil affects reward processing in the NAc in healthy subjects through enhancing more positive anticipation, and it may provide a basis for the use of this drug for treating anhedonia observed in psychiatric disorders.
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Affiliation(s)
- Takuya Funayama
- Anesthesiology and Clinical Physiology, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
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Banks ML, Bauer CT, Blough BE, Rothman RB, Partilla JS, Baumann MH, Negus SS. Abuse-related effects of dual dopamine/serotonin releasers with varying potency to release norepinephrine in male rats and rhesus monkeys. Exp Clin Psychopharmacol 2014; 22:274-284. [PMID: 24796848 PMCID: PMC4067459 DOI: 10.1037/a0036595] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
d-Amphetamine selectively promotes release of both dopamine (DA) and norepinephrine (NE) versus serotonin (5HT), and chronic d-amphetamine treatment decreases cocaine-taking behavior in rats, nonhuman primates, and humans. However, abuse liability limits the clinical utility of amphetamine maintenance for treating cocaine abuse. One strategy to improve safety and efficacy of monoamine releasers as candidate anticocaine medications has been to develop dual DA/5HT releasers like 1-napthyl-2-aminopropane (PAL-287), but the pharmacology of this class of compounds has not been extensively examined. In particular, PAL-287 has similar potencies to release DA, 5HT, and NE, and the role of manipulating NE release potency on abuse-related or anticocaine effects of dual DA/5HT releasers is not known. To address this issue, the present study compared effects of four novel DA/5HT releasers that varied >800-fold in their selectivities to release DA/5HT versus NE: [1-(5-chloro-1H-indol-3-yl)propan-2-amine (PAL-542), 1-(5-fluoro-1H-indol-3-yl)propan-2-amine (PAL-544), 1-(1H-indol-5-yl)propan-2-amine (PAL-571), and (R)-1-(1H-indol-1-yl)propain-2-amine (PAL-569). Abuse-related effects of all four compounds were evaluated in assays of intracranial self-stimulation (ICSS) in rats and cocaine discrimination in rats and monkeys, and none of the compounds reliably facilitated ICSS or substituted for cocaine. Anticocaine effects of the compound with highest selectivity to release DA/5HT versus NE (PAL-542) were tested in an assay of cocaine versus food choice in rhesus monkeys, and PAL-542 failed to reduce cocaine choice. These results suggests that potency to release NE has minimal influence on abuse liability of dual DA/5HT releasers, and reducing relative potency to release NE versus DA/5HT does not improve anticocaine efficacy.
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Affiliation(s)
- Matthew L. Banks
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA USA
,Institute for Drug and Alcohol Studies, Virginia Commonwealth University
,Corresponding Author: Department of Pharmacology and Toxicology Virginia Commonwealth University 410 N. 12 St. PO Box 980613 Richmond, VA 23298 Phone: 804-828-8466 Fax: 804-828-2117
| | - Clayton T. Bauer
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA USA
| | - Bruce E. Blough
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC USA
| | - Richard B. Rothman
- Medicinal Chemistry Section, Intramural Research Program, NIDA, Baltimore, MD USA
| | - John S. Partilla
- Medicinal Chemistry Section, Intramural Research Program, NIDA, Baltimore, MD USA
| | - Michael H Baumann
- Medicinal Chemistry Section, Intramural Research Program, NIDA, Baltimore, MD USA
| | - S. Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA USA
,Institute for Drug and Alcohol Studies, Virginia Commonwealth University
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Predicting abuse potential of stimulants and other dopaminergic drugs: overview and recommendations. Neuropharmacology 2014; 87:66-80. [PMID: 24662599 DOI: 10.1016/j.neuropharm.2014.03.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Revised: 02/26/2014] [Accepted: 03/12/2014] [Indexed: 01/09/2023]
Abstract
Examination of a drug's abuse potential at multiple levels of analysis (molecular/cellular action, whole-organism behavior, epidemiological data) is an essential component to regulating controlled substances under the Controlled Substances Act (CSA). We reviewed studies that examined several central nervous system (CNS) stimulants, focusing on those with primarily dopaminergic actions, in drug self-administration, drug discrimination, and physical dependence. For drug self-administration and drug discrimination, we distinguished between experiments conducted with rats and nonhuman primates (NHP) to highlight the common and unique attributes of each model in the assessment of abuse potential. Our review of drug self-administration studies suggests that this procedure is important in predicting abuse potential of dopaminergic compounds, but there were many false positives. We recommended that tests to determine how reinforcing a drug is relative to a known drug of abuse may be more predictive of abuse potential than tests that yield a binary, yes-or-no classification. Several false positives also occurred with drug discrimination. With this procedure, we recommended that future research follow a standard decision-tree approach that may require examining the drug being tested for abuse potential as the training stimulus. This approach would also allow several known drugs of abuse to be tested for substitution, and this may reduce false positives. Finally, we reviewed evidence of physical dependence with stimulants and discussed the feasibility of modeling these phenomena in nonhuman animals in a rational and practical fashion. This article is part of the Special Issue entitled 'CNS Stimulants'.
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Monoamine transporter inhibitors and substrates as treatments for stimulant abuse. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 69:129-76. [PMID: 24484977 DOI: 10.1016/b978-0-12-420118-7.00004-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The acute and chronic effects of abused psychostimulants on monoamine transporters and associated neurobiology have encouraged development of candidate medications that target these transporters. Monoamine transporters, in general, and dopamine transporters, in particular, are critical molecular targets that mediate abuse-related effects of psychostimulants such as cocaine and amphetamine. Moreover, chronic administration of psychostimulants can cause enduring changes in neurobiology reflected in dysregulation of monoamine neurochemistry and behavior. The current review will evaluate evidence for the efficacy of monoamine transporter inhibitors and substrates to reduce abuse-related effects of stimulants in preclinical assays of stimulant self-administration, drug discrimination, and reinstatement. In considering deployment of monoamine transport inhibitors and substrates as agonist-type medications to treat stimulant abuse, the safety and abuse liability of the medications are an obvious concern, and this will also be addressed. Future directions in drug discovery should identify novel medications that retain efficacy to decrease stimulant use but possess lower abuse liability and evaluate the degree to which efficacious medications can attenuate or reverse neurobiological effects of chronic stimulant use.
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Wood S, Sage JR, Shuman T, Anagnostaras SG. Psychostimulants and cognition: a continuum of behavioral and cognitive activation. Pharmacol Rev 2013; 66:193-221. [PMID: 24344115 PMCID: PMC3880463 DOI: 10.1124/pr.112.007054] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Psychostimulants such as cocaine have been used as performance enhancers throughout recorded history. Although psychostimulants are commonly prescribed to improve attention and cognition, a great deal of literature has described their ability to induce cognitive deficits, as well as addiction. How can a single drug class be known to produce both cognitive enhancement and impairment? Properties of the particular stimulant drug itself and individual differences between users have both been suggested to dictate the outcome of stimulant use. A more parsimonious alternative, which we endorse, is that dose is the critical determining factor in cognitive effects of stimulant drugs. Herein, we review several popular stimulants (cocaine, amphetamine, methylphenidate, modafinil, and caffeine), outlining their history of use, mechanism of action, and use and abuse today. One common graphic depiction of the cognitive effects of psychostimulants is an inverted U-shaped dose-effect curve. Moderate arousal is beneficial to cognition, whereas too much activation leads to cognitive impairment. In parallel to this schematic, we propose a continuum of psychostimulant activation that covers the transition from one drug effect to another as stimulant intake is increased. Low doses of stimulants effect increased arousal, attention, and cognitive enhancement; moderate doses can lead to feelings of euphoria and power, as well as addiction and cognitive impairment; and very high doses lead to psychosis and circulatory collapse. This continuum helps account for the seemingly disparate effects of stimulant drugs, with the same drug being associated with cognitive enhancement and impairment.
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Affiliation(s)
- Suzanne Wood
- 9500 Gilman Dr MC 0109, La Jolla, CA 92093-0109.
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30
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Federici M, Latagliata E, Rizzo F, Ledonne A, Gu H, Romigi A, Nisticò R, Puglisi-Allegra S, Mercuri N. Electrophysiological and amperometric evidence that modafinil blocks the dopamine uptake transporter to induce behavioral activation. Neuroscience 2013; 252:118-24. [DOI: 10.1016/j.neuroscience.2013.07.071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 07/07/2013] [Accepted: 07/31/2013] [Indexed: 10/26/2022]
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A translational pharmacology approach to understanding the predictive value of abuse potential assessments. Behav Pharmacol 2013; 24:410-36. [PMID: 23873088 DOI: 10.1097/fbp.0b013e3283644d2e] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Within the drug development industry the assessment of abuse potential for novel molecules involves the generation and review of data from multiple sources, ranging from in-vitro binding and functional assays through to in-vivo nonclinical models in mammals, as well as collection of information from studies in humans. This breadth of data aligns with current expectations from regulatory agencies in both the USA and Europe. To date, there have been a limited number of reviews on the predictive value of individual models within this sequence, but there has been no systematic review on how each of these models contributes to our overall understanding of abuse potential risk. To address this, we analyzed data from 100 small molecules to compare the predictive validity for drug scheduling status of a number of models that typically contribute to the abuse potential assessment package. These models range from the assessment of in-vitro binding and functional profiles at receptors or transporters typically associated with abuse through in-vivo models including locomotor activity, drug discrimination, and self-administration in rodents. Data from subjective report assessments in humans following acute dosing of compounds were also included. The predictive value of each model was then evaluated relative to the scheduling status of each drug in the USA. In recognition of the fact that drug scheduling can be influenced by factors other than the pharmacology of the drug, we also evaluated the predictive value of each assay for the outcome of the human subjective effects assessment. This approach provides an objective and statistical assessment of the predictive value of many of the models typically applied within the pharmaceutical industry to evaluate abuse potential risk. In addition, the impact of combining information from multiple models was examined. This analysis adds to our understanding of the predictive value of each model, allows us to critically evaluate the benefits and limitations of each model, and provides a method for identifying opportunities for improving our assessment and prediction of abuse liability risk in the future.
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Wisor J. Modafinil as a catecholaminergic agent: empirical evidence and unanswered questions. Front Neurol 2013; 4:139. [PMID: 24109471 PMCID: PMC3791559 DOI: 10.3389/fneur.2013.00139] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/06/2013] [Indexed: 11/21/2022] Open
Abstract
Modafinil, in its two clinical formulations (Provigil® and Nuvigil®), is a widely prescribed wake-promoting therapeutic agent. It binds competitively to the cell-membrane dopamine (DA) transporter and is dependent on catecholaminergic (dopaminergic and adrenergic) signaling for its wake-promoting effects. The clinical spectrum of effects for modafinil is distinct from the effects seen with other catecholaminergic agents. Relative to other commonly used agents that act through catecholaminergic mechanisms, modafinil has a relatively low abuse potential, produces wakefulness with an attenuated compensatory sleep recovery thereafter, and does not ameliorate cataplexy in narcolepsy. These clinically relevant phenomenological differences between modafinil and agents such as amphetamines and cocaine do not eliminate catecholaminergic effects as a possible mediator of its wake-promoting action; they merely reflect its unique pharmacological profile. Modafinil is an exceptionally weak, but apparently very selective, DA transporter inhibitor. The pharmacodynamic response to modafinil, as measured by DA levels in brain microdialyzate, is protracted relative to other agents that act via catecholaminergic mechanisms. The conformational constraints on the interaction of modafinil with the DA transporter – and probably, as a consequence, its effects on trace amine receptor signaling in the catecholaminergic cell – are unique among catecholaminergic agents. These unique pharmacological properties of modafinil should be considered both in seeking to thoroughly understand its putatively elusive mechanism of action and in the design of novel therapeutic agents.
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Affiliation(s)
- Jonathan Wisor
- Department of Integrative Physiology and Neuroscience, Sleep and Performance Research Center, Washington State University , Spokane, WA , USA
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Quisenberry AJ, Prisinzano T, Baker LE. Combined effects of modafinil and d-amphetamine in male Sprague-Dawley rats trained to discriminate d-amphetamine. Pharmacol Biochem Behav 2013; 110:208-15. [PMID: 23880213 DOI: 10.1016/j.pbb.2013.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 07/09/2013] [Accepted: 07/13/2013] [Indexed: 10/26/2022]
Abstract
Modafinil is a novel wake-promoting drug with FDA approval for the treatment of sleep-related disorders that has recently been investigated as a potential agonist replacement therapy for psychostimulant dependence. Previous research in animals and humans indicates modafinil has a lower abuse liability than traditional psychostimulants, although few studies have carefully assessed modafinil's stimulus properties in combination with other psychostimulants. The current study trained male Sprague-Dawley rats to discriminate subcutaneous injections of 0.3 mg/kg (n=8) or 1.0 mg/kg d-amphetamine (n=8) from saline under an FR 20 schedule of food reinforcement and substitution tests were administered with d-amphetamine (0.03-1.0 mg/kg, s.c.), modafinil (32-256 mg/kg, i.g.), and a low modafinil dose (32 mg/kg, i.g.) in combination with d-amphetamine (0.03-1.0 mg/kg, s.c.) to determine if these drugs have additive effects. The selective D2 dopamine agonist, PNU-91356A, was also tested as a positive control and ethanol and morphine were tested as negative controls. Results indicate that modafinil produced dose-dependent and statistically significant d-amphetamine-lever responding in both groups and nearly complete substitution in animals trained to discriminate 1.0 mg/kg d-amphetamine. Modafinil pretreatment slightly increased the discrimination of low d-amphetamine doses in animals trained to discriminate 0.3 mg/kg d-amphetamine. These results support previous findings that modafinil and d-amphetamine may have additive effects. In consideration of recent interests in modafinil as an agonist treatment for psychostimulant dependence, additional preclinical investigations utilizing other methodologies to examine modafinil in combination with other stimulants, such as behavioral sensitization paradigms or drug self-administration, may be of interest.
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Heal DJ, Buckley NW, Gosden J, Slater N, France CP, Hackett D. A preclinical evaluation of the discriminative and reinforcing properties of lisdexamfetamine in comparison to D-amfetamine, methylphenidate and modafinil. Neuropharmacology 2013; 73:348-58. [PMID: 23748096 DOI: 10.1016/j.neuropharm.2013.05.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 04/03/2013] [Accepted: 05/13/2013] [Indexed: 12/20/2022]
Abstract
Lisdexamfetamine dimesylate, which consists of L-lysine covalently bound to D-amfetamine, is the first prodrug for treating ADHD. Its metabolic conversion to yield D-amfetamine by rate-limited, enzymatic hydrolysis is unusual because it is performed by peptidases associated with red blood cells. Other stimulants shown to be effective in managing ADHD include D-amfetamine, methylphenidate and modafinil. All have the potential for misuse or recreational abuse. The discriminative and reinforcing effects of these compounds were determined in rats using a 2-choice, D-amfetamine (0.5 mg/kg, i.p.)-cued drug-discrimination test, and by substitution for intravenous cocaine in self-administration. Lisdexamfetamine (0.5-1.5 mg/kg [D-amfetamine base], p.o.) generalised to saline when tested 15 min post-dosing, but dose-dependently generalised to d-amfetamine at 60 min. At 120 min, its D-amfetamine-like effects were substantially diminished. At 15 min, methylphenidate (3.0-10 mg/kg, p.o.) and D-amfetamine (0.1-1.5 mg/kg, p.o.) dose-dependently generalised to the intraperitoneal D-amfetamine cue. Switching to the intraperitoneal route reduced the interval required for lisdexamfetamine to be recognised as D-amfetamine-like, but did not alter its potency. Switching to intraperitoneal injection increased the potency of methylphenidate and D-amfetamine by 3.4× and 2.2×, respectively. Modafinil (50-200 mg/kg, i.p.) generalised partially, but not fully, to d-amfetamine. Methylphenidate (0.1, 0.3, 1.0 mg/kg/injection, i.v.) maintained robust self-administration at the 2 highest doses. Neither lisdexamfetamine (0.05, 0.15 or 0.5 mg/kg/injection [D-amfetamine base], i.v.) nor modafinil (0.166, 0.498 or 1.66 mg/kg/injection, i.v.) served as reinforcers. The results reveal important differences between the profiles of these stimulants. Lisdexamfetamine did not serve as a positive reinforcer in cocaine-trained rats, and although it generalised fully to D-amfetamine, its discriminative effects were markedly influenced by its unusual pharmacokinetics.
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Affiliation(s)
- David J Heal
- RenaSci Ltd, BioCity Nottingham, Pennyfoot Street, Nottingham NG1 1GF, UK.
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Banks ML, Blough BE, Fennell TR, Snyder RW, Negus SS. Role of phenmetrazine as an active metabolite of phendimetrazine: evidence from studies of drug discrimination and pharmacokinetics in rhesus monkeys. Drug Alcohol Depend 2013; 130:158-66. [PMID: 23211394 PMCID: PMC3616150 DOI: 10.1016/j.drugalcdep.2012.10.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/30/2012] [Accepted: 10/30/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Monoamine releasers such as d-amphetamine that selectively promote release of dopamine/norepinephrine versus serotonin are one class of candidate medications for treating cocaine dependence; however, their clinical utility is limited by undesirable effects such as abuse liability. Clinical utility of these compounds may be increased by development of prodrugs to reduce abuse potential by slowing onset of drug effects. This study examined the behavioral and pharmacokinetic profile of the Schedule III compound phendimetrazine, which may serve as a prodrug for the N-demethylated metabolite and potent dopamine/norepinephrine releaser phenmetrazine. METHODS Monkeys (n = 5) were trained in a two-key food-reinforced discrimination procedure to discriminate cocaine (0.32 mg/kg, IM) from saline, and the potency and time course of cocaine-like discriminative stimulus effects were determined for (+)-phenmetrazine, (-)-phenmetrazine, (+)-phendimetrazine, (-)-phendimetrazine, and (±)-phendimetrazine. Parallel pharmacokinetic studies in the same monkeys examined plasma phenmetrazine and phendimetrazine levels for correlation with cocaine-like discriminative stimulus effects. RESULTS Both isomers of phenmetrazine, and the racemate and both isomers of phendimetrazine, produced dose- and time-dependent substitution for the discriminative stimulus effects of cocaine, with greater potency residing in the (+) isomers. In general, plasma phenmetrazine levels increased to similar levels after administration of behaviorally active doses of either phenmetrazine or phendimetrazine. CONCLUSIONS These results support the hypothesis that phenmetrazine is an active metabolite that contributes to the effects of phendimetrazine. However, behavioral effects of phendimetrazine had a more rapid onset than would have been predicted by phenmetrazine levels alone, suggesting that other mechanisms may also contribute.
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Affiliation(s)
- Matthew L Banks
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA.
| | - Bruce E Blough
- Center for Organic and Medicinal Chemistry, Research Triangle Institute International, Research Triangle Park, NC, USA 27709
| | - Timothy R. Fennell
- Department of Pharmacology and Toxicology, Research Triangle Institute International, Research Triangle Park, NC, USA 27709
| | - Rodney W. Snyder
- Department of Pharmacology and Toxicology, Research Triangle Institute International, Research Triangle Park, NC, USA 27709
| | - S. Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA 23298
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Loland CJ, Mereu M, Okunola OM, Cao J, Prisinzano TE, Mazier S, Kopajtic T, Shi L, Katz JL, Tanda G, Newman AH. R-modafinil (armodafinil): a unique dopamine uptake inhibitor and potential medication for psychostimulant abuse. Biol Psychiatry 2012; 72:405-13. [PMID: 22537794 PMCID: PMC3413742 DOI: 10.1016/j.biopsych.2012.03.022] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/24/2012] [Accepted: 03/16/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND (±)-Modafinil has piqued interest as a treatment for attention-deficit/hyperactivity disorder and stimulant dependence. The R-enantiomer of modafinil might have unique pharmacological properties that should be further investigated. METHODS (±)-Modafinil and its R-(-)- and S-(+)-enantiomers were synthesized and tested for inhibition of [(3)H] dopamine (DA) uptake and [(3)H]WIN 35428 binding in human dopamine transporter (DAT) wild-type and mutants with altered conformational equilibria. Data were compared with cocaine and the atypical DA uptake inhibitor, JHW 007. R- and S-modafinil were also evaluated in microdialysis studies in the mouse nucleus accumbens shell and in a cocaine discrimination procedure. RESULTS (±)-, R-, and S-modafinil bind to the DAT and inhibit DA uptake less potently than cocaine, with R-modafinil having approximately threefold higher affinity than its S-enantiomer. Molecular docking studies revealed subtle differences in binding modes for the enantiomers. R-modafinil was significantly less potent in the DAT Y156F mutant compared with wild-type DAT, whereas S-modafinil was affected less. Studies with the Y335A DAT mutant showed that the R- and S-enantiomers tolerated the inward-facing conformation better than cocaine, which was further supported by [2-(trimethylammonium)ethyl]-methanethiosulfonate reactivity on the DAT E2C I159C. Microdialysis studies demonstrated that both R- and S-modafinil produced increases in extracellular DA concentrations in the nucleus accumbens shell less efficaciously than cocaine and with a longer duration of action. Both enantiomers fully substituted in mice trained to discriminate cocaine from saline. CONCLUSIONS R-modafinil displays an in vitro profile different from cocaine. Future trials with R-modafinil as a substitute therapy with the potential benefit of cognitive enhancement for psychostimulant addiction are warranted.
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Shuman T, Cai DJ, Sage JR, Anagnostaras SG. Interactions between modafinil and cocaine during the induction of conditioned place preference and locomotor sensitization in mice: implications for addiction. Behav Brain Res 2012; 235:105-12. [PMID: 22963989 DOI: 10.1016/j.bbr.2012.07.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/18/2012] [Accepted: 07/27/2012] [Indexed: 11/28/2022]
Abstract
Modafinil is a wake-promoting drug effective at enhancing alertness and attention with a variety of approved and off-label applications. The mechanism of modafinil is not well understood but initial studies indicated a limited abuse potential. A number of recent publications, however, have shown that modafinil can be rewarding under certain conditions. The present study assessed the reinforcing properties of modafinil using conditioned place preference and locomotor sensitization in mice. Experiment 1 examined a high dose of modafinil (75 mg/kg) as well as its interactions with cocaine (15 mg/kg). Cocaine alone and modafinil co-administered with cocaine induced sensitization of locomotor activity; modafinil alone showed little or no locomotor sensitization. Animals given modafinil alone, cocaine alone, and modafinil plus cocaine exhibited a strong and roughly equivalent place preference. When tested for sensitization using a low challenge dose of modafinil, cross-sensitization was observed in all cocaine-pretreated mice. Experiment 2 examined a low dose of modafinil that is similar to the dose administered to humans and has been shown to produce cognitive enhancements in mice. Low dose modafinil (0.75 mg/kg) did not produce conditioned place preference or locomotor sensitization. Together, these results suggest that modafinil has the potential to produce reward, particularly in cocaine addicts, and should be used with caution. However, the typical low dose administered likely moderates these effects and may account for lack of addiction seen in humans.
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Affiliation(s)
- Tristan Shuman
- Molecular Cognition Laboratory, Department of Psychology, University of California, San Diego, La Jolla, CA 92093-0109, United States.
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Differential effects of modafinil, methamphetamine, and MDMA on agonistic behavior in male mice. Pharmacol Biochem Behav 2012; 102:215-23. [DOI: 10.1016/j.pbb.2012.04.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 04/23/2012] [Accepted: 04/28/2012] [Indexed: 01/13/2023]
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Chronic modafinil effects on drug-seeking following methamphetamine self-administration in rats. Int J Neuropsychopharmacol 2012; 15:919-29. [PMID: 21733228 PMCID: PMC3258466 DOI: 10.1017/s1461145711000988] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Acute administration of the cognitive enhancing drug, modafinil (Provigil®), reduces methamphetamine (Meth) seeking following withdrawal from daily self-administration. However, the more clinically relevant effects of modafinil on Meth-seeking after chronic treatment have not been explored. Here, we determined the impact of modafinil on Meth-seeking after chronic daily treatment during extinction or abstinence following Meth self-administration. Rats self-administered intravenous Meth during daily 2-h sessions for 14 d, followed by extinction sessions or abstinence. During this period, rats received daily injections of vehicle, 30, or 100 mg/kg modafinil and were then tested for Meth-seeking via cue, Meth-primed, and context-induced reinstatement at early and late withdrawal time-points. We found that chronic modafinil attenuated relapse to a Meth-paired context, decreased conditioned cue-induced and Meth-primed reinstatement, and resulted in enduring reductions in Meth-seeking even after discontinuation of treatment. Additionally, we determined that only a very high dose of modafinil (300 mg/kg) during maintenance of self-administration had an impact on Meth intake. These results validate and extend clinical and preclinical findings that modafinil may be a viable treatment option for Meth addiction.
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Dackis CA, Kampman KM, Lynch KG, Plebani JG, Pettinati HM, Sparkman T, O'Brien CP. A double-blind, placebo-controlled trial of modafinil for cocaine dependence. J Subst Abuse Treat 2012; 43:303-12. [PMID: 22377391 DOI: 10.1016/j.jsat.2011.12.014] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 11/29/2011] [Accepted: 12/12/2011] [Indexed: 11/17/2022]
Abstract
This is a randomized, double-blind, placebo-controlled study of modafinil treatment for cocaine dependence. Patients (N = 210) who were actively using cocaine at baseline were randomized to 8 weeks of modafinil (0 mg/day, 200 mg/day, or 400 mg/day) combined with once-weekly cognitive-behavioral therapy. Our primary efficacy measure was cocaine abstinence, based on urine benzoylecgonine (BE) levels, with secondary measures of craving, cocaine withdrawal, retention, and tolerability. We found no significant differences between modafinil and placebo patients on any of these measures. However, there was a significant gender difference in that male patients treated with 400 mg/day tended to be more abstinent than their placebo-treated counterparts (p = .06). Our negative findings might be explained by gender differences and/or inadequate psychosocial treatment intensity in patients with severe cocaine dependence.
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Affiliation(s)
- Charles A Dackis
- University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Rush CR, Stoops WW. Agonist replacement therapy for cocaine dependence: a translational review. Future Med Chem 2012; 4:245-65. [PMID: 22300101 PMCID: PMC3292908 DOI: 10.4155/fmc.11.184] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cocaine use disorders are prevalent throughout the world. Agonist replacement therapy is among the most effective strategies for managing substance use disorders including nicotine and opioid dependence. This paper reviews the translational literature, including preclinical experiments, human laboratory studies and clinical trials, to determine whether agonist-replacement therapy is a viable strategy for managing cocaine dependence. Discussion is limited to transporter blockers (i.e., methylphenidate) and releasers (i.e., amphetamine analogs) that are available for use in humans in the hope of impacting clinical research and practice more quickly. The translational review suggests that agonist-replacement therapy, especially monoamine releasers, may be effective for managing cocaine dependence. Future directions for medications development are also discussed because the viability of agonist-replacement therapy for cocaine dependence may hinge on identifying novel compounds or formulations that have less abuse and diversion potential.
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Affiliation(s)
- Craig R Rush
- Department of Behavioral Science, University of Kentucky, College of Medicine, Medical Behavioral Science Building, Lexington, KY 40536-0086, USA.
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Modulation of fronto-cortical activity by modafinil: a functional imaging and fos study in the rat. Neuropsychopharmacology 2012; 37:822-37. [PMID: 22048464 PMCID: PMC3260987 DOI: 10.1038/npp.2011.260] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Modafinil (MOD) is a wake-promoting drug with pro-cognitive properties. Despite its increasing use, the neuronal substrates of MOD action remain elusive. In particular, animal studies have highlighted a putative role of diencephalic areas as primary neuronal substrate of MOD action, with inconsistent evidence of recruitment of fronto-cortical areas despite the established pro-cognitive effects of the drug. Moreover, most animal studies have employed doses of MOD of limited clinical relevance. We used pharmacological magnetic resonance imaging (phMRI) in the anesthetized rat to map the circuitry activated by a MOD dose producing clinically relevant plasma exposure, as here ascertained by pharmacokinetic measurements. We observed prominent and sustained activation of the prefrontal and cingulate cortex, together with weaker but significant activation of the somatosensory cortex, medial thalamic domains, hippocampus, ventral striatum and dorsal raphe. Correlation analysis of phMRI data highlighted enhanced connectivity within a neural network including dopamine projections from the ventral tegmental area to the nucleus accumbens. The pro-arousing effect of MOD was assessed using electroencephalographic recording under anesthetic conditions comparable to those used for phMRI, together with the corresponding Fos immunoreactivity distribution. MOD produced electroencephalogram desynchronization, resulting in reduced delta and increased theta frequency bands, and a pattern of Fos induction largely consistent with the phMRI study. Altogether, these findings show that clinically relevant MOD doses can robustly activate fronto-cortical areas involved in higher cognitive functions and a network of pro-arousing areas, which provide a plausible substrate for the wake-promoting and pro-cognitive effects of the drug.
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Pharmacotherapeutics directed at deficiencies associated with cocaine dependence: focus on dopamine, norepinephrine and glutamate. Pharmacol Ther 2012; 134:260-77. [PMID: 22327234 DOI: 10.1016/j.pharmthera.2012.01.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 01/19/2012] [Indexed: 11/20/2022]
Abstract
Much effort has been devoted to research focused on pharmacotherapies for cocaine dependence yet there are no FDA-approved medications for this brain disease. Preclinical models have been essential to defining the central and peripheral effects produced by cocaine. Recent evidence suggests that cocaine exerts its reinforcing effects by acting on multiple neurotransmitter systems within mesocorticolimibic circuitry. Imaging studies in cocaine-dependent individuals have identified deficiencies in dopaminergic signaling primarily localized to corticolimbic areas. In addition to dysregulated striatal dopamine, norepinephrine and glutamate are also altered in cocaine dependence. In this review, we present these brain abnormalities as therapeutic targets for the treatment of cocaine dependence. We then survey promising medications that exert their therapeutic effects by presumably ameliorating these brain deficiencies. Correcting neurochemical deficits in cocaine-dependent individuals improves memory and impulse control, and reduces drug craving that may decrease cocaine use. We hypothesize that using medications aimed at reversing known neurochemical imbalances is likely to be more productive than current approaches. This view is also consistent with treatment paradigms used in neuropsychiatry and general medicine.
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Abstract
The stimulants, amphetamine and methylphenidate, have long been the mainstay of attention-deficit hyperactivity disorder (ADHD) therapy. They are rapidly effective and are generally the first medications selected by physicians. In the development of alternative pharmacological approaches, drug candidates have been evaluated with a wide diversity of mechanisms. All of these developments have contributed real progress in the field, but there is still much room for improvement and unmet clinical need in ADHD pharmacotherapy. The availability of a wide range of compounds with a high degree of specificity for individual monoamines (dopamine and noradrenaline) and/or different pharmacological mechanisms has refined our understanding of the essential elements for optimum pharmacological effect in managing ADHD. In this chapter, we review the pharmacology of the different classes of drug used to treat ADHD and provide a neurochemical rationale, predominantly from the use of in vivo microdialysis experiments, to explain their relative efficacy and potential to elicit side effects. In addition, we will consider how predictions based on results from animal models translate into clinical outcomes. The treatment of ADHD is also described from the perspective of the physician. Finally, the new research development for drugs to treat ADHD is discussed.
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Affiliation(s)
- David J Heal
- RenaSci Consultancy Ltd, BioCity, Nottingham, NG1 1GF, UK,
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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 PMCID: PMC3197159 DOI: 10.1371/journal.pone.0025790] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [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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Wuo-Silva R, Fukushiro DF, Borçoi AR, Fernandes HA, Procópio-Souza R, Hollais AW, Santos R, Ribeiro LTC, Corrêa JMRM, Talhati F, Saito LP, Aramini TCF, Kameda SR, Bittencourt LRA, Tufik S, Frussa-Filho R. Addictive potential of modafinil and cross-sensitization with cocaine: a pre-clinical study. Addict Biol 2011; 16:565-79. [PMID: 21790900 DOI: 10.1111/j.1369-1600.2011.00341.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Repeated or even a single exposure to drugs of abuse can lead to persistent locomotor sensitization, which is the result of an abundance of neuroplastic changes occurring within the circuitry involved in motivational behavior and is thought to play a key role in certain aspects of drug addiction. There is substantial controversy about the addictive potential of modafinil, a wake-promoting drug used to treat narcolepsy that is increasingly being used as a cognitive enhancer and has been proposed as a pharmacotherapy for cocaine dependence. Male mice were used to investigate the ability of modafinil to induce locomotor sensitization after repeated or single administration in mice. Bidirectional cross-sensitization with cocaine and modafinil-induced conditioned place preference were also evaluated. Both repeated and single exposure to moderate and high doses of modafinil produced a pronounced locomotor sensitization that cross-sensitized in a bidirectional way with cocaine. Remarkably, when cocaine and modafinil were repeatedly administered sequentially, their behavioral sensitization was additive. Supporting these behavioral sensitization data, modafinil produced a pronounced conditioned place preference in the mouse. Taken together, the present findings provide pre-clinical evidence for the addictive potential of modafinil. Our data also strongly suggest that similar neural substrates are involved in the psychomotor/rewarding effects of modafinil and cocaine.
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Abstract
RATIONALE Neuroimaging techniques have led to significant advances in our understanding of the neurobiology of drug taking and the treatment of drug addiction in humans. Neuroimaging approaches provide a powerful translational approach that can link findings from humans and laboratory animals. OBJECTIVE This review describes the utility of neuroimaging toward understanding the neurobiological basis of drug taking and documents the close concordance that can be achieved among neuroimaging, neurochemical, and behavioral endpoints. RESULTS The study of drug interactions with dopamine and serotonin transporters in vivo has identified pharmacological mechanisms of action associated with the abuse liability of stimulants. Neuroimaging has identified the extended limbic system, including the prefrontal cortex and anterior cingulate, as important neuronal circuitry that underlies drug taking. The ability to conduct within-subject longitudinal assessments of brain chemistry and neuronal function has enhanced our efforts to document long-term changes in dopamine D2 receptors, monoamine transporters, and prefrontal metabolism due to chronic drug exposure. Dysregulation of dopamine function and brain metabolic changes in areas involved in reward circuitry have been linked to drug taking behavior, cognitive impairment, and treatment response. CONCLUSIONS Experimental designs employing neuroimaging should consider well-documented determinants of drug taking, including pharmacokinetic considerations, subject history, and environmental variables. Methodological issues to consider include limited molecular probes, lack of neurochemical specificity in brain activation studies, and the potential influence of anesthetics in animal studies. Nevertheless, these integrative approaches should have important implications for understanding drug taking behavior and the treatment of drug addiction.
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Nguyen TL, Tian YH, You IJ, Lee SY, Jang CG. Modafinil-induced conditioned place preference via dopaminergic system in mice. Synapse 2011; 65:733-41. [PMID: 21157933 DOI: 10.1002/syn.20892] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 10/31/2010] [Indexed: 12/22/2022]
Abstract
Modafinil, a psychostimulant, is used in the treatment of narcolepsy, shift work sleep disorder, and excessive daytime sleepiness associated with obstructive sleep apnea. Preclinical and clinical studies suggest that modafinil may have reinforcing effects. However, a possible rewarding property of modafinil has not been fully investigated. In this study, we assessed the potential rewarding property of modafinil using the conditioned place preference (CPP) paradigm in mice. Using radiolabeled ligands, we observed changes in dopamine, glutamate, and GABA receptor binding in the brains of mice after treatment with modafinil. Modafinil produced significant CPP in mice at an intraperitoneal (i.p.) dose of 125 mg kg⁻¹ and prevented normal body weight gain of mice in a dose-dependent manner. A significant reduction in normal body weight gain was observed when mice were administrated 125 mg kg⁻¹ modafinil. In addition, there were widespread changes in receptor binding in the brains of modafinil-treated mice; Dopamine D₁ binding was increased in the caudate putamen, the accumbens, and the substantia nigra, while dopamine D₂ binding was decreased in the caudate putamen and the accumbens. Dopamine transporter (DAT) binding was increased in the prefrontal cortex, the caudate putamen, and the nucleus accumbens. No changes were observed in NMDA and GABA(A) receptor binding. These data indicate that modafinil had a significant rewarding property and could be abused as a recreational drug. Dopamine systems may play a key role in the rewarding property of modafinil.
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Affiliation(s)
- Thi-Lien Nguyen
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea
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O’Connor EC, Chapman K, Butler P, Mead AN. The predictive validity of the rat self-administration model for abuse liability. Neurosci Biobehav Rev 2011; 35:912-38. [DOI: 10.1016/j.neubiorev.2010.10.012] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 10/21/2010] [Accepted: 10/23/2010] [Indexed: 11/15/2022]
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