Double-blind placebo-controlled evaluation of the PROMETA™ protocol for methamphetamine dependence

Psychosocial and pharmacologic interventions for problematic methamphetamine use: Findings from a scoping review of the literature

RATIONALE

Methamphetamine use and related harms have risen at alarming rates. While several psychosocial and pharmacologic interventions have been described in the literature, there is uncertainty regarding the best approach for the management of methamphetamine use disorder (MUD) and problematic methamphetamine use (PMU). We conducted a scoping review of recent systematic reviews (SR), clinical practice guidelines (CPG), and primary controlled studies of psychosocial and pharmacologic treatments for MUD/PMU.

METHODS

Guided by an a priori protocol, electronic database search updates (e.g., MEDLINE, Embase) were performed in February 2022. Screening was performed following a two-stage process, leveraging artificial intelligence to increase efficiency of title and abstract screening. Studies involving individuals who use methamphetamine, including key subgroups (e.g. those with mental health comorbidities; adolescents/youths; gay, bisexual, and other men who have sex with men) were sought. We examined evidence related to methamphetamine use, relapse, use of other substances, risk behaviors, mental health, harms, and retention. Figures, tables and descriptive synthesis were used to present findings from the identified literature.

RESULTS

We identified 2 SRs, one CPG, and 54 primary studies reported in 69 publications that met our eligibility criteria. Amongst SRs, one concluded that psychostimulants had no effect on methamphetamine abstinence or treatment retention while the other reported no effect of topiramate on cravings. The CPG strongly recommended psychosocial interventions as well as self-help and family support groups for post-acute management of methamphetamine-related disorders. Amongst primary studies, many interventions were assessed by only single studies; contingency management was the therapy most commonly associated with evidence of potential effectiveness, while bupropion and modafinil were analogously the most common pharmacologic interventions. Nearly all interventions showed signs of potential benefit on at least one methamphetamine-related outcome measure.

DISCUSSION

This scoping review provides an overview of available interventions for the treatment of MUD/PMU. As most interventions were reported by a single study, the effectiveness of available interventions remains uncertain. Primary studies with longer durations of treatment and follow-up, larger sample sizes, and of special populations are required for conclusive recommendations of best approaches for the treatment of MUD/PMU.

Psychiatric Uses of Gabapentin

OBJECTIVE

This article reviews evidence-based psychiatric uses of gabapentin, along with associated risks.

METHOD OF RESEARCH

An extensive literature review was conducted, primarily of articles searchable in PubMed, relating to psychiatric uses, safety, and adverse effects of gabapentin.

RESULTS

Evidence supports gabapentin as a treatment for alcohol withdrawal and alcohol use disorder. There is sufficient evidence to consider gabapentin as a third-line treatment for social anxiety disorder and severe panic disorder. Evidence does not support the use of gabapentin for bipolar disorder, major depressive disorder (MDD), posttraumatic stress disorder (PTSD), obsessive compulsive disorder (OCD), stimulant use disorder, or opioid withdrawal. Risks of gabapentin use are highest among those with a history of a substance use disorder and those concurrently taking opioids.

CONCLUSION

While gabapentin has a place in psychiatry for a select few indications, the literature does not support its use for many studied diagnoses.

Pharmacological Treatment of Methamphetamine/Amphetamine Dependence: A Systematic Review

BACKGROUND

Stimulant drugs are second only to cannabis as the most widely used class of illicit drug globally, accounting for 68 million past-year consumers. Dependence on amphetamines (AMPH) or methamphetamine (MA) is a growing global concern. Yet, there is no established pharmacotherapy for AMPH/MA dependence. A comprehensive assessment of the research literature on pharmacotherapy for AMPH/MA dependence may inform treatment guidelines and future research directions.

METHODS

We systematically reviewed the peer-reviewed literature via the electronic databases PubMed, EMBASE, CINAHL and SCOPUS for randomised controlled trials reported in the English language examining a pharmacological treatment for AMPH/MA dependence or use disorder. We included all studies published to 19 June 2019. The selected studies were evaluated for design; methodology; inclusion and exclusion criteria; sample size; pharmacological and (if included) psychosocial interventions; length of follow-up and follow-up schedules; outcome variables and measures; results; overall conclusions and risk of bias. Outcome measures were any reported impact of treatment related to AMPH/MA use.

RESULTS

Our search returned 43 studies that met our criteria, collectively enrolling 4065 participants and reporting on 23 individual pharmacotherapies, alone or in combination. Disparate outcomes and measures (n = 55 for the primary outcomes) across studies did not allow for meta-analyses. Some studies demonstrated mixed or weak positive signals (often in defined populations, e.g. men who have sex with men), with some variation in efficacy signals dependent on baseline frequency of AMPH/MA use. The most consistent positive findings have been demonstrated with stimulant agonist treatment (dexamphetamine and methylphenidate), naltrexone and topiramate. Less consistent benefits have been shown with the antidepressants bupropion and mirtazapine, the glutamatergic agent riluzole and the corticotropin releasing factor (CRF-1) antagonist pexacerfont; whilst in general, antidepressant medications (e.g. selective serotonin reuptake inhibitors [SSRIs], tricyclic antidepressants [TCAs]) have not been effective in reducing AMPH/MA use.

CONCLUSIONS

No pharmacotherapy yielded convincing results for the treatment of AMPH/MA dependence; mostly studies were underpowered and had low treatment completion rates. However, there were positive signals from several agents that warrant further investigation in larger scale studies; agonist therapies show promise. Common outcome measures should include change in use days. Future research must address the heterogeneity of AMPH/MA dependence (e.g. coexisting conditions, severity of disorder, differences between MA and AMPH dependence) and the role of psychosocial intervention.

Review: Does Gabapentin Relieve Opioids, Cannabis and Methamphetamines Addictions?

The study reviews the suitability of using Gabapentin for treating opioid, cannabis and methamphetamine use disorders. This revision consists of 61 biographical references based on a PubMed database search (January of 1983-May of 2018). Gabapentin displayed respectively 50% and 66.7% of success for treating methamphetamine dependence and opioid withdrawal symptoms. Furthermore, a few research studies have reported Gabapentin´s efficacy for alleviating cannabis dependence (two studies), and cannabis withdrawal symptoms (one study). Similarly, a single study reported Gabapentin reduction of opioid consumption during the detoxification process. Based on the revision, we can conclude that: (a) Gabapentin is useful for treating opioid withdrawal symptoms, (b) additional studies are necessary for elucidating the effectiveness of Gabapentin for treating methamphetamine dependence, cannabis dependence and its withdrawal symptoms, and (c) more studies are necessary to confirm the efficacy of Gabapentin in reducing opioid consumption during detoxification.

Pharmacotherapy for methamphetamine/amphetamine use disorder-a systematic review and meta-analysis

AIMS

Addiction to methamphetamine/amphetamine (MA/A) is a major public health problem. Currently there are no pharmacotherapies for MA/A use disorder that have been approved for use by the US Food and Drug Administration or the European Medicines Agency. We reviewed the effectiveness of pharmacotherapy for MA/A use disorder to assess the quality, publication bias and overall strength of the evidence.

METHODS

Systematic review and meta-analysis. We searched multiple data sources (MEDLINE, PsycINFO and Cochrane Library) to April 2019 for systematic reviews (SRs) and randomized controlled trials (RCTs). Included studies recruited adults who had MA/A use disorder; sample sizes ranged from 19 to 229 participants. Outcomes of interest were abstinence, defined as 3 or more consecutive weeks with negative urine drug screens (UDS); overall use, analyzed as the proportion of MA/A negative UDS specimens; and treatment retention. One SR of pharmacotherapies for MA/A use disorder and 17 additional RCTs met our inclusion criteria encompassing 17 different drugs (antidepressants, antipsychotics, psychostimulants, anticonvulsants and opioid antagonists). We combined the findings of trials with comparable interventions and outcome measures in random-effects meta-analyses. We assessed quality, publication bias and the strength of evidence for each outcome using standardized criteria.

RESULTS

There was low-strength evidence from two RCTs that methylphenidate may reduce MA/A use: 6.5 versus 2.8% MA/A-negative UDS in one study (n = 34, P = 0.008) and 23 versus 16% in another study (n = 54, P = 0.047). Antidepressants as a class had no statistically significant effect on abstinence or retention on the basis of moderate strength evidence. Studies of anticonvulsants, antipsychotics (aripiprazole), opioid antagonists (naltrexone), varenicline and atomoxetine provided either low-strength or insufficient evidence of no effect on the outcomes of interest. Many of the studies had high or unclear risk of bias.

CONCLUSIONS

On the basis of low- to moderate-strength evidence, most medications evaluated for methamphetamine/amphetamine use disorder have not shown a statistically significant benefit. However, there is low-strength evidence that methylphenidate may reduce use.

Pharmacotherapeutic strategies for methamphetamine use disorder: mind the subgroups

Introduction: Drug use related deaths are increasing and the lack of effective treatment for psychostimulants can be largely held responsible. Particularly, no pharmacotherapy is approved for methamphetamine (METH) use disorder despite decades of research. Only psychosocial interventions are clinically used, with limited long-term recovery and relapse.Areas covered: This review aims to select and describe the most relevant findings to date. Selected clinical trials were found in PubMed using the following keywords ('methamphetamine') and ('addiction' OR 'withdrawal' OR 'treatment' OR 'pharmacotherapy'). Randomized placebo-controlled trials enrolling treatment-seeking METH-dependent subjects and inherent secondary analysis were included.Expert opinion: Overall, end-of-treatment abstinence, reduced METH use or lower relapse rates were seen on METH dependent subgroups or attained significance only following post hoc analysis, irrespective of the medication tested. For example, light and heavy METH users seem to respond differently to pharmacotherapy. This together with the heterogeneous nature of the METH dependent population strongly suggests that some drugs herein described (e.g. mirtazapine, methylphenidate) should be further tested in clinical trials focused on subgroups. Lastly, objective measures, such as urinalysis, are mandatory to include in clinical trials and early treatment response and/or medication compliance should be carefully monitored and considered as predictors of success/failure.

Use of Gabapentin in the Treatment of Substance Use and Psychiatric Disorders: A Systematic Review

Objective: Gabapentin (GBP) is an anticonvulsant medication that is also used to treat restless legs syndrome (RLS) and posttherapeutic neuralgia. GBP is commonly prescribed off-label for psychiatric disorders despite the lack of strong evidence. However, there is growing evidence that GBP may be effective and clinically beneficial in both psychiatric disorders and substance use disorders. This review aimed to perform a systematic analysis of peer-reviewed published literature on the efficacy of GBP in the treatment of psychiatric disorders and substance use disorders. Methods: This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The PubMed and Ovid MEDLINE literature databases were screened and filtered by using specific search terms and inclusion/exclusion criteria. The full texts of selected studies were subsequently retrieved and reviewed. The search terms generated 2,604 results from the databases. After excluding all duplicates, 1,088 citations were left. Thereafter, we applied inclusion and exclusion criteria; a total of 54 papers were retained for detailed review. Results: This literature review concludes that GBP appears to be effective in the treatment of various forms of anxiety disorders. It shows some effectiveness in bipolar disorder as an adjunctive therapeutic agent, while the evidence for monotherapy is inconclusive. In substance use disorders, GBP is effective for acute alcohol withdrawal syndrome (AWS) with mild to moderate severity; it reduces cravings, improves the rate of abstinence, and delays return to heavy drinking. GBP may have some therapeutic potential in the treatment of opioid addiction and cannabis dependence, but there is limited evidence to support its use. No significant benefit of GBP has been conclusively observed in the treatment of OCD, PTSD, depression, or cocaine and amphetamine abuse. Conclusion: GBP appears to be effective in some forms of anxiety disorders such as preoperative anxiety, anxiety in breast cancer survivors, and social phobia. GBP has shown to be safe and effective in the treatment of alcohol dependence. However, the literature suggests that GBP is effective as an adjunctive medication rather than a monotherapy. More clinical trials with larger patient populations are needed to support gabapentin's off-label use in psychiatric disorders and substance use disorders. It is worth noting that numerous clinical studies that are discussed in this review are open-label trials, which are inherently less rigorously analyzed. Therefore, more extensive investigations are required to examine not only the efficacy of GBP, but also its safety and tolerance.

Methamphetamine-Related Disorders

BACKGROUND

Methamphetamine is considered more dangerous than other stimulants because of its acute complications, long-term neurotoxicity, and potential for drug dependence. Until now, there have been no evidence-based guidelines for the treatment of methamphetamine-related disorders, either in Germany or abroad.

METHODS

A systematic literature search was performed on the treatment of methamphetamine-related disorders. Based on this literature review, a multidisciplinary expert panel developed recommendations using the nominal group technique.

RESULTS

The evidence base for the treatment of methamphetamine-related disorders is sparse. The efficacy of psychotherapeutic techniques such as cognitive behavioral therapy and contingency management and the efficacy of complex, disorder-specific treatment programs have been proven in ran - domized controlled trials, but it remains unclear which method is best. Persons carrying a diagnosis of substance abuse should be offered psychotherapy. Structured exercise programs, whether self-directed or professionally led, can improve addiction-specific endpoints as well as comorbid disorders and should, therefore, be offered as well. Pharmacotherapy has shown little to no effect in relatively low-quality clinical trials with low case numbers and high dropout rates, and therefore only a few weak recommendations were made. These include tranquilizers for the short-term treatment of agitation and atypical antipsychotics if necessary. Attempts to substitute other substances, such as methylphenidate or dexamphetamine, for methamphetamine have not yielded any robust evidence to date. Sertraline should not be administered due to serious adverse events.

CONCLUSION

Many of the recommendations in the guideline are made with a weak grade of recommendation because of the poor evidence base and the modest size of the reported therapeutic effects. In acute situations, symptomoriented treatment is recommended. Psychotherapy and exercise should be offered as well.

Pharmacotherapy for amphetamine dependence: A systematic review

BACKGROUND

Demand for treatment for amphetamine use is increasing internationally. Establishing effective pharmacotherapy provides broader treatment options for people who are dependent on amphetamine and may encourage engagement in evidence-based behavioral treatment. This study aimed to identify medicines that have potential in improving treatment outcomes for people who are dependent on amphetamines.

METHODS

Medline, PsycINFO, Embase and the Cochrane Database of Systematic Reviews were searched from 1997 to 2012 and again from 2013 to 2016. Studies on medications for amphetamine/methamphetamine dependence treatment were selected and assessed by two independent researchers. A meta-narrative review approach was used to synthesize results.

RESULTS

A total of 49 studies investigating 20 potential pharmacotherapies were eligible for inclusion. Of these, 35 studies related to 33 level II quality randomized controlled trials (RCTs). Five medications were subject to multiple RCTs. Four of these medicines demonstrated some limited evidence of benefit for reducing amphetamine use: methylphenidate (as reported in three studies), bupropion (in three studies), modafinil (two studies), and naltrexone (one study). Four RCTs of dexamphetamine suggest its benefit on secondary outcomes such as treatment retention, but not for reducing amphetamine use. Six other medicines indicate the potential for efficacy, but the number of studies is too small to draw conclusions.

CONCLUSIONS

No medicine has as yet demonstrated sufficient, consistent evidence of effectiveness to support its use in routine treatment. High study drop-out and poor medication adherence limits the strength of evidence and raises important clinical questions about how to improve treatment engagement and outcomes.

Gabapentin for the treatment of alcohol use disorder

INTRODUCTION

Alcohol misuse is the fifth leading risk factor for premature death and disability worldwide. Fewer than 10% of afflicted Americans receive pharmacological treatment for alcohol use disorder. Gabapentin is a calcium channel GABAergic modulator that is widely used for pain. Studies showing reduced drinking and decreased craving and alcohol-related disturbances in sleep and affect in the months following alcohol cessation suggest therapeutic potential for alcohol use disorder. Areas covered: Human laboratory and clinical studies assessing gabapentin for alcohol use disorder are reviewed. Data were obtained by searching for English peer-reviewed articles on PubMed, reference lists of identified articles, and trials registered on clinicaltrials.gov. Additionally, the mechanism of action of gabapentin specific to alcohol use disorder, and studies of gabapentin for alcohol withdrawal and non-alcohol substance use disorders are summarized. Expert opinion: Alcohol use disorder represents a challenge and large, unmet medical need. Evidence from single-site studies lend support to the safety and efficacy of gabapentin as a novel treatment for alcohol use disorder, with unique benefits for alcohol-related insomnia and negative affect, relative to available treatments. Proprietary gabapentin delivery systems may open a path to pivotal trials and registration of gabapentin as a novel treatment for alcohol use disorder.

Tamoxifen and amphetamine abuse: Are there therapeutic possibilities?

Although best known as a selective estrogen receptor modulator (SERM), tamoxifen is a drug with a wide range of activities. Tamoxifen has demonstrated some efficacy has a therapeutic for bipolar mania and is believed to exert these effects through inhibition of protein kinase C (PKC). As the symptoms of amphetamine treatment in rodents are believed to mimic the symptoms of a manic episode, many of the preclinical studies for this indication have demonstrated that tamoxifen inhibits amphetamine action. The amphetamine-induced increase in extracellular dopamine which gives rise to the 'manic' effects is due to interaction of amphetamine with the dopamine transporter. We and others have demonstrated that PKC reduces amphetamine-induced reverse transport through the dopamine transporter. In this review, we will outline the actions of tamoxifen as a SERM and further detail another known action of tamoxifen-inhibition of PKC. We will summarize the literature showing how tamoxifen affects amphetamine action. Finally, we will present our hypothesis that tamoxifen, or an analog, could be used therapeutically to reduce amphetamine abuse in addition to treating mania.

Adding Genetic Testing to Evidence-Based Guidelines to Determine the Safest and Most Effective Chronic Pain Treatment for Injured Workers

Published guidelines for treating injured workers include the need for personalized treatment to manage chronic pain symptoms and increase functional status. However, they often fail to clarify how to objectively personalize these treatments. Further, certain patients need analgesic relief beyond the short term. In these cases, it is not sufficient or reasonable to utilize the typical broad protocol-based justifications for reduction of opioids and other medications in a haphazard manner based purely on poor response, without attempting to elucidate possible pharmacogenetic reasons for this. These guidelines acknowledge the problem of substance abuse and set forth methods for treatment and prevention. Although it has been established in the scientific community that an individual's experience of pain and likelihood for addiction both have genetic components, genetic testing is not routinely included as part of the overall treatment plan for injured workers with chronic pain. Because decisions in cases of workplace injury should be based on scientific evidence, genetic testing results can add some objective information to the existing subjective and objective clinical data; help ascertain the efficacy and potential for toxicity of treatment; and therefore provide more information for accurate clinical decisions. We propose the addition of genetic testing to consensus guidelines for treating injured workers in order to improve patients' functional status, increase productivity, improve safety of prescribing, decrease the likelihood of substance abuse, and save on overall healthcare costs.

Gabapentin Therapy in Psychiatric Disorders: A Systematic Review

OBJECTIVE

Gabapentin is commonly used off-label in the treatment of psychiatric disorders with success, failure, and controversy. A systematic review of the literature was performed to elucidate the evidence for clinical benefit of gabapentin in psychiatric disorders.

DATA SOURCES

Bibliographic reference searches for gabapentin use in psychiatric disorders were performed in PubMed and Ovid MEDLINE search engines with no language restrictions from January 1, 1983, to October 1, 2014, excluding nonhuman studies. For psychiatric references, the keywords bipolar, depression, anxiety, mood, posttraumatic stress disorder (posttraumatic stress disorder and PTSD), obsessive-compulsive disorder (obsessive-compulsive disorder and OCD), alcohol (abuse, dependence, withdraw), drug (abuse, dependence, withdraw), opioid (abuse, dependence, withdraw), cocaine (abuse, dependence, withdraw), and amphetamine (abuse, dependence, withdraw) were crossed with gabapentin OR neurontin.

STUDY SELECTION AND DATA EXTRACTION

The resulting 988 abstracts were read by 2 reviewers; references were excluded if gabapentin was not a study compound or psychiatric symptoms were not studied. The resulting references were subsequently read, reviewed, and analyzed; 219 pertinent to gabapentin use in psychiatric disorders were retained. Only 34 clinical trials investigating psychiatric disorders contained quality of evidence level II-2 or higher.

RESULTS

Gabapentin may have benefit for some anxiety disorders, although there are no studies for generalized anxiety disorder. Gabapentin has less likely benefit adjunctively for bipolar disorder. Gabapentin has clearer efficacy for alcohol craving and withdrawal symptoms and may have a role in adjunctive treatment of opioid dependence. There is no clear evidence for gabapentin therapy in depression, PTSD prevention, OCD, or other types of substance abuse. Limitations of available data include variation in dosing between studies, gabapentin as monotherapy or adjunctive treatment, and differing primary outcomes between trials.

CONCLUSIONS

Further research is required to better clarify the benefit of gabapentin in psychiatric disorders.

Sustained-release methylphenidate in methamphetamine dependence treatment: a double-blind and placebo-controlled trial

BACKGROUND

The objective of this randomized, double-blind, placebo-controlled study was to evaluate the efficacy of sustained-release methylphenidate (MPH-SR) in treatment of methamphetamine dependence.

METHODS

Fifty-six individuals who met DSM-IV-TR criteria for methamphetamine dependence participated in this 10-week trial. The participants were randomly allocated into two groups and received 18 to 54 mg/day sustained-released methylphenidate or placebo for 10 weeks. Craving was evaluated by a visual analogue craving scale every week. Urinary screening test for methamphetamine was carried out each week. The Beck Depression Inventory-II (BDI-II) was used to monitor participant depressive symptoms at baseline and bi-weekly during the treatment period.

RESULTS

At the end of the trial, the MPH-SR group was less methamphetamine positive compared to the placebo group and the difference was significant (p = 0.03). By the end of the study, MPH-SR group showed significantly less craving scores compared to the placebo group [MD (95% CI) = -10.28(0.88-19.18), t(54) = 2.19, p = 0.03]. There was greater improvement in the depressive symptoms scores in the intervention group compared to the placebo group [MD (95% CI) =2.03(0.31-3.75), t (54) =2.37, p = 0.02].

CONCLUSION

Sustained-released methylphenidate was safe and well tolerated among active methamphetamine users and significantly reduced methamphetamine use, craving and depressive symptoms.

TRIAL REGISTRATION

IRCT201202281556N38.

Methamphetamine: an update on epidemiology, pharmacology, clinical phenomenology, and treatment literature

BACKGROUND

Despite initial reports of a decline in use in the early 2000s, methamphetamine remains a significant public health concern with known neurotoxic and neurocognitive effects to the user. The goal of this review is to update the literature on methamphetamine use and addiction since its assent to peak popularity in 1990s.

METHODS

We first review recent epidemiological reports with a focus on methamphetamine accessibility, changes in use and disorder prevalence rates over time, and accurate estimates of the associated burden of care to the individual and society. Second, we review methamphetamine pharmacology literature with emphasis on the structural and functional neurotoxic effects associated with repeated use of the drug. Third, we briefly outline the findings on methamphetamine-related neurocognitive deficits as assessed via behavioral and neuroimaging paradigms. Lastly, we review the clinical presentation of methamphetamine addiction and the evidence supporting the available psychosocial and pharmacological treatments within the context of an addiction biology framework.

CONCLUSION

Taken together, this review provides a broad-based update of the available literature covering methamphetamine research over the past two decades and concludes with recommendations for future research.

Sustained-release methylphenidate in a randomized trial of treatment of methamphetamine use disorder

BACKGROUND AND AIMS

No effective pharmacotherapy for methamphetamine (MA) use disorder has yet been found. This study evaluated sustained-release methylphenidate (MPH-SR) compared with placebo (PLA) for treatment of MA use disorder in people also undergoing behavioral support and motivational incentives.

DESIGN

This was a randomized, double-blind, placebo-controlled design with MPH-SR or PLA provided for 10 weeks (active phase) followed by 4 weeks of single-blind PLA. Twice-weekly clinic visits, weekly group counseling (CBT) and motivational incentives (MI) for MA-negative urine drug screens (UDS) were included.

SETTING

Treatment sites were in Los Angeles, California (LA) and Honolulu, Hawaii (HH), USA.

PARTICIPANTS

A total of 110 MA-dependent (via DSM-IV) participants (LA = 90; HH = 20).

MEASUREMENTS

The primary outcome measure is self-reported days of MA use during the last 30 days of the active phase. Included in the current analyses are drug use (UDS and self-report), retention, craving, compliance (dosing, CBT, MI), adverse events and treatment satisfaction.

FINDINGS

No difference was found between treatment groups in self-reported days of MA use during the last 30 days of the active phase (P = 0.22). In planned secondary outcomes analyses, however, the MPH group had fewer self-reported MA use days from baseline through the active phase compared with the PLA group (P = 0.05). The MPH group also had lower craving scores and fewer marijuana-positive UDS than the PLA group in the last 30 days of the active phase. The two groups had similar retention, other drug use, adverse events and treatment satisfaction.

CONCLUSIONS

Methylphenidate may lead to a reduction in concurrent methamphetamine use when provided as treatment for patients undergoing behavioral support for moderate to severe methamphetamine use disorder, but this requires confirmation.

Combination pharmacotherapies for stimulant use disorder: a review of clinical findings and recommendations for future research

Despite concerted efforts to identify a pharmacotherapy for managing stimulant use disorders, no widely effective medications have been approved. Innovative strategies are necessary to develop successful pharmacotherapies for stimulant use disorders. This manuscript reviews human laboratory studies and clinical trials to determine whether one such strategy, use of combination pharmacotherapies, holds promise. The extant literature shows that combination pharmacotherapy produced results that were better than placebo treatment, especially with medications shown to have efficacy as monotherapies. However, many studies did not compare individual constituents to the combination treatment, making it impossible to determine whether combination treatment is more effective than monotherapy. Future research should systematically compare combined treatments with individual agents using medications showing some efficacy when tested alone.

Pharmacotherapy of amphetamine-type stimulant dependence: an update

ISSUES

Methamphetamine- or amphetamine-type stimulants are the second most frequently used illicit drug worldwide, second only to cannabis. Behavioural treatments are efficacious, but their impact is limited underscoring the need for other treatment options, notably, pharmacotherapy.

APPROACH

A review of randomised controlled trials of pharmacotherapies for methamphetamine- or amphetamine-type stimulants was performed using PubMed and Google Scholar databases. Evidence for efficacy of medications is reported.

KEY FINDINGS

Clinical trials have yielded no broadly effective pharmacotherapy. Promising signals have been observed for methylphenidate, naltrexone, bupropion and mirtazapine in subgroups of patients in reducing stimulant use (e.g. patients with less severe dependence at baseline and men who have sex with men), though none has produced an unambiguous, replicable signal of efficacy.

IMPLICATIONS

Problems in Phase II trials, including high dropout rates, missing data and a lack of agreement on outcomes, complicate efforts to find a broadly effective pharmacotherapy for amphetamine-type stimulant disorders. Efforts to address these problems include calls for better validation of pharmacological target exposure, receptor binding and functional modulation. As well, there is a need for agreement in using findings from preclinical and early phases of the medication development process for selecting better pharmacotherapy candidates.

CONCLUSION

After over 20 years of efforts worldwide to develop a broadly effective medication for dependence on methamphetamine- or amphetamine-type stimulants, no candidate has emerged. This highlights the need for new compounds, consistent and stringent research methods, better integration between preclinical and clinical stages of medication development, and improved collaboration between government, industry and researchers.