Similar and Different? Subjective Effects of Methylphenidate and Cocaine in Opioid-Maintained Patients

Methylphenidate with or without fluoxetine triggers reinstatement of cocaine seeking behavior in rats

Methylphenidate (MP) is commonly prescribed to treat attention-deficit hyperactivity disorder (ADHD). MP is also taken for non-medical purposes as a recreational drug or "cognitive enhancer". Combined exposure to MP and selective serotonin reuptake inhibitors such as fluoxetine (FLX) can also occur, such as in the treatment of ADHD with depression comorbidity or when patients taking FLX use MP for non-medical purposes. It is unclear if such exposure could subsequently increase the risk for relapse in former cocaine users. We investigated if an acute challenge with MP, FLX, or the combination of MP + FLX could trigger reinstatement of cocaine seeking behavior in a model for relapse in rats. Juvenile rats self-administered cocaine (600 µg/kg/infusion, 1-2 h/day, 7-8 days) and then underwent extinction and withdrawal during late adolescence-early adulthood. Reinstatement was tested at a low dose of MP (2 mg/kg, I.P., comparable to doses used therapeutically) or a high dose of MP (5 mg/kg, comparable to doses used recreationally or as a cognitive enhancer), with or without FLX (2.5-5 mg/kg, I.P.). An acute challenge with the high dose of MP (5 mg/kg), with or without FLX, reinstated cocaine seeking behavior to levels comparable to those seen after an acute challenge with cocaine (15 mg/kg, I.P.). The low dose of MP (2 mg/kg) with or without FLX did not reinstate cocaine seeking behavior. Our results suggest that acute exposure to a high dose of MP, with or without FLX, may increase the risk for relapse in individuals who used cocaine during the juvenile period.

Concomitant Drug Use among Opioid-Dependent Patients with and without Attention Deficit Hyperactivity Disorder: Does Methylphenidate Merit a Trial?

INTRODUCTION

Concomitant drug use is common among opioid-dependent patients in maintenance therapy. Attention deficit hyperactivity disorder (ADHD), a common comorbidity among opioid users, is associated with a higher risk of concomitant drug use. Earlier studies showed that methylphenidate (MPH) can reduce cocaine consumption among patients with ADHD. The use of MPH as an agonist-replacement or maintenance therapy in cocaine-dependent patients without ADHD is also common in Switzerland, despite a lack of supporting evidence. The aim of this study was to assess concomitant cocaine, amphetamine, MDMA, MPH, and heroin use among patients in opioid maintenance therapy either with or without comorbid ADHD. We expected stimulant consumption to be higher in patients with cocaine dependence and comorbid ADHD and that use of MPH would not lead to a reduction in cocaine consumption in patients without ADHD. We therefore evaluated correlations between use of MPH and cocaine consumption and between MPH consumption and cocaine craving within the two groups.

METHODS

This cross-sectional study included 94 opioid-dependent patients in maintenance therapy in an outpatient department of the Psychiatric Hospital of Zurich. The patients were divided into two groups based on comorbid ADHD; a group with ADHD (N = 27) and a group without ADHD (N = 67). Drug use was assessed using 3-month hair analysis.

RESULTS

We did not find significant differences in the number of patients using cocaine, amphetamine, MDMA, or heroin between groups with or without ADHD. With respect to cocaine use, 85.2 percent of patients in the ADHD group and 73.1 percent in the non-ADHD group were users. The non-ADHD group showed a significant positive correlation between the concentration of MPH and cocaine in hair samples (p < 0.05), and a positive correlation between cocaine craving and the concentration of MPH in hair samples (p = 0.065). These two trends were not evident in the ADHD group.

CONCLUSION

Among patients without ADHD, use of MPH correlates with higher cocaine consumption and craving. Conversely, no significant correlation was found between MPH and cocaine use in patients with ADHD. Our study adds to the evidence that MPH confers negative effects in cocaine users without ADHD and should thus have no place in the treatment of these patients.

Gaps in Evidence-based Treatment of Concurrent Attention Deficit Hyperactivity Disorder and Opioid Use Disorder: A Scoping Review

OBJECTIVES

To describe the effectiveness of medications for the treatment of opioid use disorder (OUD) and attention deficit/hyperactivity disorder (ADHD).

DATA SOURCES

Literature search of PubMed, Embase, Web of Science, CINAHL, Medline, PsycINFO, and Google Scholar was performed for studies published from inception to October 25, 2022.

STUDY SELECTION AND DATA EXTRACTION

Studies were included if patients were diagnosed with OUD and ADHD and had pharmacotherapy for either condition. Abstracts, commentaries, reviews, case reports, case series, non-English articles, and animal studies were omitted.

DATA SYNTHESIS

This review found 18 studies. Treatment of ADHD was evaluated for impact on ADHD and OUD outcomes, while treatment of OUD was evaluated for OUD-related outcomes. Outcomes assessed included markers for symptom intensity, adherence, and treatment failure. While results were mixed, treatment of ADHD was largely associated with improvements in ADHD severity and retention in OUD treatment programs. ADHD severity was associated with higher rates of illicit substance abuse and worse OUD-related outcomes. It could not be determined which medications for treatment of OUD should be prioritized.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review summarized key findings from studies that treated ADHD or OUD among dually diagnosed patients and highlighted methodological considerations for future research.

CONCLUSIONS

Treatment of ADHD is warranted among patients with OUD and ADHD to improve retention in OUD treatment programs and reduce illicit substance abuse. Pharmacotherapy for the treatment of ADHD or OUD should continue to be determined based on patients' characteristics and the capabilities of the treatment program.

An update on the clinical pharmacology of methylphenidate: therapeutic efficacy, abuse potential and future considerations

INTRODUCTION

Methylphenidate remains a first-line medication for treating ADHD in children and adults. However, its behavioral pharmacological similarities to methamphetamine and cocaine have historically created concern for its potential as a drug of abuse. In September 2019, the FDA published a docket requesting comments for the development of abuse deterrent formulations for CNS stimulants, emphasizing the abuse of methylphenidate as a public health concern.

AREAS COVERED

We conducted a narrative review of research on the clinical pharmacology, therapeutic efficacy, and abuse potential of methylphenidate.

EXPERT OPINION

Several studies indicate that methylphenidate has at least some abuse potential. Methylphenidate, amphetamine, methamphetamine, and cocaine overlap in their subjective, reinforcing, and discriminative stimulus effects. Regardless, methylphenidate remains an efficacious treatment for ADHD in children and adults when properly adhered to, especially when paired with non-pharmacological treatments. The development of abuse deterrent formulations of methylphenidate is warranted.

Designer drugs: mechanism of action and adverse effects

Psychoactive substances with chemical structures or pharmacological profiles that are similar to traditional drugs of abuse continue to emerge on the recreational drug market. Internet vendors may at least temporarily sell these so-called designer drugs without adhering to legal statutes or facing legal consequences. Overall, the mechanism of action and adverse effects of designer drugs are similar to traditional drugs of abuse. Stimulants, such as amphetamines and cathinones, primarily interact with monoamine transporters and mostly induce sympathomimetic adverse effects. Agonism at μ-opioid receptors and γ-aminobutyric acid-A (GABAA) or GABAB receptors mediates the pharmacological effects of sedatives, which may induce cardiorespiratory depression. Dissociative designer drugs primarily act as N-methyl-D-aspartate receptor antagonists and pose similar health risks as the medically approved dissociative anesthetic ketamine. The cannabinoid type 1 (CB1) receptor is thought to drive the psychoactive effects of synthetic cannabinoids, which are associated with a less desirable effect profile and more severe adverse effects compared with cannabis. Serotonergic 5-hydroxytryptamine-2A (5-HT2A) receptors mediate alterations of perception and cognition that are induced by serotonergic psychedelics. Because of their novelty, designer drugs may remain undetected by routine drug screening, thus hampering evaluations of adverse effects. Intoxication reports suggest that several designer drugs are used concurrently, posing a high risk for severe adverse effects and even death.

Methylphenidate for Attention-Deficit and Hyperactivity Disorder in Adult Patients With Substance Use Disorders: Good Clinical Practice

Attention-deficit and hyperactivity disorder (ADHD) is a widespread neurodevelopmental disorder in children and adolescents, persisting into adulthood in a majority of them. ADHD and substance use disorders (SUDs) commonly co-occur in the clinical adult population. The higher-than-normal prevalence rates of SUDs in people with ADHD indicate increased risk for developing SUD. This narrative review deals with the question of whether or not adults with both disorders should be treated with methylphenidate (MPH), addressing specific issues surrounding this form of treatment. MPH is considered as first-line pharmacotherapy for ADHD. However, because of its stimulant-like reinforcing properties, MPH has a significant addictive potential to which persons with SUDs are especially susceptible. Appropriate treatment is therefore complex. Because of concerns about misuse and diversion of MPH medication, clinicians may be reluctant to use MPH to manage ADHD symptoms in these patients. However, it is essential to diagnose and treat ADHD adequately as appropriate therapy reduces the impairments, as well as the risk of developing comorbid disorders and poor treatment response. MPH should not be deprived of these patients because of the risk for misuse, especially as several strategies can be applied to minimize this risk. To conclude, carefully applied guideline-based diagnostics to clarify the potential presence of ADHD as well as a responsible prescription practice in a well-defined therapeutic setting with reliable monitoring of medication intake and regular consultations are essential conditions for a safe and proficient MPH treatment of ADHD in patients with SUD.

Pharmacological profile of methylphenidate-based designer drugs

BACKGROUND

Methylphenidate-based designer drugs are new psychoactive substances (NPS) that are used outside medical settings and their pharmacology is largely unexplored. The aim of the present study was to characterize the pharmacology of methylphenidate-based substances in vitro.

METHODS

We determined the potencies of the methylphenidate-based NPS N-benzylethylphenidate, 3,4-dichloroethylphenidate, 3,4-dichloromethylphenidate, ethylnaphthidate, ethylphenidate, 4-fluoromethylphenidate, isopropylphenidate, 4-methylmethylphenidate, methylmorphenate, and propylphenidate and the potencies of the related compounds cocaine and modafinil with respect to norepinephrine, dopamine, and serotonin transporter inhibition in transporter-transfected human embryonic kidney 293 cells. We also investigated monoamine efflux and monoamine receptor and transporter binding affinities. Furthermore, we assessed the cell integrity under assay conditions.

RESULTS

All methylphenidate-based substances inhibited the norepinephrine and dopamine transporters 4 to >1000-fold more potently than the serotonin transporter. Similar to methylphenidate and cocaine, methylphenidate-based NPS did not elicit transporter-mediated efflux of monoamines. Besides binding to monoamine transporters, several test drugs had affinity for adrenergic, serotonergic, and rat trace amine-associated receptors but not for dopaminergic or mouse trace amine-associated receptors. No cytotoxicity was observed after drug treatment at assay concentrations.

CONCLUSION

Methylphenidate-based substances had pharmacological profiles similar to methylphenidate and cocaine. The predominant actions on dopamine transporters vs. serotonin transporters may be relevant when considering abuse liability. This article is part of the Special Issue entitled 'Designer Drugs and Legal Highs.'