Prescription psychostimulants for the treatment of amphetamine-type stimulant use disorder: A systematic review and meta-analysis of randomized placebo-controlled trials

Contextual and psychosocial factors influencing drug reward in humans: The importance of non-drug reinforcement

The reinforcing efficacy, or behavior-strengthening effect, of a substance is a critical determinant of substance use typically quantified by measuring behavioral allocation to the substance under schedules of reinforcement with escalating response requirements. Although responses on these tasks are often used to indicate stable reinforcing effects or trait-level abuse potential for an individual, task designs often demonstrate within-person variability across varying degrees of a constraint within experimental procedures. As a result, quantifying behavioral allocation is an effective approach for measuring the impact of contextual and psychosocial factors on substance reward. We review studies using laboratory self-administration, behavioral economic purchase tasks, and ambulatory assessments to quantify the impact of various contextual and psychosocial factors on behavioral allocation toward consumption of a substance. We selected these assessment approaches because they cover the translational spectrum from experimental control to ecological relevance, with consistent support across these approaches representing greater confidence in the effect. Conceptually, we organized factors that influence substance value into two broad categories: factors that influence the cost/benefit ratio of the substance (social context, stress and affect, cue exposure), and factors that influence the cost/benefit ratio of an alternative (alternative non-drug reinforcers, alternative drug reinforcers, and opportunity costs). We conclude with an overview of future research directions and considerations for clinical application.

Efficacy and Safety of Modafinil for Treatment of Amphetamine-Type Stimulant Use Disorder: A Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Trials: Efficacité et innocuité du modafinil pour le traitement des troubles liés à l'usage de stimulants de type amphétamine : revue systématique et méta-analyse d'essais randomisés contrôlés par placebo

INTRODUCTION

Amphetamine-type stimulants (ATSs) are related to significant harm worldwide, with limited effective pharmacological treatments for ATS use disorder (ATSUD). Modafinil has been explored as a potential treatment for ATSUD. This systematic review and meta-analysis (PROSPERO ID: CRD42023388487) aimed to evaluate the efficacy and safety of modafinil for the treatment of ATSUD.

METHODS

A comprehensive search of major indexing sources and trial registries, from inception to search date, was conducted on February 15, 2023, and updated on October 31, 2023. Eligible studies were randomized placebo-controlled trials (RCTs) of modafinil in individuals meeting the criteria for the Diagnostic and Statistical Manual of Mental Disorders, fourth and fifth editions, diagnoses of ATSUD. Eligible studies were assessed for risk of bias, using the Cochrane Risk of Bias tool. The primary outcome included the effect of modafinil on ATS use. Secondary outcomes included retention in treatment, ATS craving, treatment discontinuation due to adverse events (AEs), and serious AEs. Subgroup analysis by modafinil dose was conducted where appropriate. Risk ratio (RR) or Peto's odds ratio (OR) was calculated for the meta-analysis of dichotomous variables and standardized mean difference (SMD) was calculated for the random-effect meta-analysis of continuous variables.

RESULTS

Five RCTs (N = 451 participants) were included. Modafinil did not significantly impact ATS use (RR = 0.99; 95% CI, 0.97 to 1.02; p = 0.655), retention in treatment (RR = 1.02; 95% CI, 0.91 to 1.14; p = 0.799), ATS craving (SMD = -0.36; 95% CI, -1.19 to 0.47; p = 0.398), or treatment discontinuation due to AEs (Peto's OR = 0.48; 95% CI, 0.20 to 1.14; p = 0.100). These results were consistent across subgroup analyses. More episodes of serious AEs were reported in the modafinil group than in the placebo group, at higher doses (Peto's OR = 4.80; 95% CI, 1.18 to 19.56, p = 0.029).

CONCLUSION

There is currently no evidence suggesting that modafinil has a statistically significant effect on efficacy outcomes in populations with ATSUD. Continued research into effective treatments and harm reduction strategies for ATSUD is essential.

A phase 3 randomised double-blind placebo-controlled trial of mirtazapine as a pharmacotherapy for methamphetamine use disorder: a study protocol for the Tina Trial

BACKGROUND

There are no approved pharmacotherapies for methamphetamine use disorder. Two preliminary phase 2 randomised controlled trials have found mirtazapine, a tetracyclic antidepressant, to be effective in reducing methamphetamine use. The proposed Tina Trial is the first phase 3 placebo-controlled randomised trial to examine the effectiveness and safety of mirtazapine as an outpatient pharmacotherapy for methamphetamine use disorder.

METHODS

This is a multi-site phase 3 randomised, double-blind, placebo-controlled parallel trial. Participants are randomly allocated (1:1) to receive either mirtazapine (30 mg/day for 12 weeks) or matched placebo, delivered as a take-home medication. The target population is 340 people aged 18-65 years who have moderate to severe methamphetamine use disorder. The trial is being conducted through outpatient alcohol and other drug treatment clinics in Australia. The primary outcome is measured as self-reported days of methamphetamine use in the past 4 weeks at week 12. Secondary outcomes are methamphetamine-negative oral fluid samples, depressive symptoms, sleep quality, HIV risk behaviour and quality of life. Other outcomes include safety (adverse events), tolerability, and health service use. Medication adherence is being monitored using MEMS® Smart Caps fitted to medication bottles.

DISCUSSION

This trial will provide information on the safety and effectiveness of mirtazapine as a pharmacotherapy for methamphetamine use disorder when delivered as an outpatient medication in routine clinical practice. If found to be safe and effective, this trial will support an application for methamphetamine use disorder to be included as a therapeutic indication for the prescription of mirtazapine.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12622000235707. Registered on February 9, 2022.