Prescription psychostimulants for cocaine use disorder: A review from molecular basis to clinical approach

Behavioral and neuronal extracellular vesicle biomarkers associated with nicotine's enhancement of the reinforcing strength of cocaine in female and male monkeys

While the majority of people with cocaine use disorders (CUD) also co-use tobacco/nicotine, most preclinical cocaine research does not include nicotine. The present study examined nicotine and cocaine co-use under several conditions of intravenous drug self-administration in monkeys, as well as potential peripheral biomarkers associated with co-use. In Experiment 1, male rhesus monkeys (N = 3) self-administered cocaine (0.001-0.1 mg/kg/injection) alone and with nicotine (0.01-0.03 mg/kg/injection) under a progressive-ratio schedule of reinforcement. When nicotine was added to cocaine, there was a significant leftward/upward shift in the number of injections received. In Experiment 2, socially housed female and male cynomolgus monkeys (N = 14) self-administered cocaine under a concurrent drug-vs-food choice schedule of reinforcement. Adding nicotine to the cocaine solution shifted the cocaine dose-response curves to the left, with more robust shifts noted in the female animals. There was no evidence of social rank differences. To assess reinforcing strength, delays were added to the presentation of drug; the co-use of nicotine and cocaine required significantly longer delays to decrease drug choice, compared with cocaine alone. Blood samples obtained post-session were used to analyze concentrations of neuronally derived small extracellular vesicles (NDE); significant differences in NDE profile were observed for kappa-opioid receptors when nicotine and cocaine were co-used compared with each drug alone and controls. These results suggest that drug interactions involving the co-use of nicotine and cocaine are not simply changing potency, but rather resulting in changes in reinforcing strength that should be utilized to better understand the neuropharmacology of CUD and the evaluation of potential treatments.

Promising immunomodulators for management of substance and alcohol use disorders

INTRODUCTION

The neuroimmune system has emerged as a novel target for the treatment of substance use disorders (SUDs), with immunomodulation producing encouraging therapeutic benefits in both preclinical and clinical settings.

AREAS COVERED

In this review, we describe the mechanism of action and immune response to methamphetamine, opioids, cocaine, and alcohol. We then discuss off-label use of immunomodulators as adjunctive therapeutics in the treatment of neuropsychiatric disorders, demonstrating their potential efficacy in affective and behavioral disorders. We then discuss in detail the mechanism of action and recent findings regarding the use of ibudilast, minocycline, probenecid, dexmedetomidine, pioglitazone, and cannabidiol to treat (SUDs). These immunomodulators are currently being investigated in clinical trials described herein, specifically for their potential to decrease substance use, withdrawal severity, central and peripheral inflammation, comorbid neuropsychiatric disorder symptomology, as well as their ability to improve cognitive outcomes.

EXPERT OPINION

We argue that although mixed, findings from recent preclinical and clinical studies underscore the potential benefit of immunomodulation in the treatment of the behavioral, cognitive, and inflammatory processes that underlie compulsive substance use.

Structural bioinformatics studies of serotonin, dopamine and norepinephrine transporters and their AlphaFold2 predicted water-soluble QTY variants and uncovering the natural mutations of L->Q, I->T, F->Y and Q->L, T->I and Y->F

Monoamine transporters including transporters for serotonin, dopamine, and norepinephrine play key roles in monoaminergic synaptic signaling, involving in the molecular etiology of a wide range of neurological and physiological disorders. Despite being crucial drug targets, the study of transmembrane proteins remains challenging due to their localization within the cell membrane. To address this, we present the structural bioinformatics studies of 7 monoamine transporters and their water-soluble variants designed using the QTY code, by systematically replacing the hydrophobic amino acids leucine (L), valine (V), isoleucine (I) and phenylalanine (F) with hydrophilic amino acids (glutamine (Q), threonine (T) and tyrosine (Y). The resulting QTY variants, despite significant protein transmembrane sequence differences (44.27%-51.85%), showed similar isoelectric points (pI) and molecular weights. While their hydrophobic surfaces significantly reduced, this change resulted in a minimal structural alteration. Quantitatively, Alphafold2 predicted QTY variant structures displayed remarkable similarity with RMSD 0.492Å-1.619Å. Accompanied by the structural similarities of substituted amino acids in the context of 1.5Å electron density maps, our study revealed multiple QTY and reverse QTY variations in genomic databases. We further analyzed their phenotypical and topological characteristics. By extending evolutionary game theory to the molecular foundations of biology, we provided insights into the evolutionary dynamics of chemically distinct alpha-helices, their usage in different chemotherapeutic applications, and open possibilities of diagnostic medicine. Our study rationalizes that QTY variants of monoamine transporters may not only become distinct tools for medical, structural, and evolutionary research, but these transporters may also emerge as contemporary therapeutic targets, providing a new approach to treatment for several conditions.

Perceptions of prospective pharmaceutical stimulant substitution treatments among people who use illicit stimulants in Vancouver, Canada

BACKGROUND

Stimulant-involved overdose deaths are increasing, driven by polysubstance use and adulteration of the illicit drug supply. While emerging evidence for prescription stimulant substitution is promising, there are no approved treatment options for stimulant use disorder that address the realities of an unpredictable drug supply. This study explores treatment experiences of people who use illicit stimulants (PWUS) to identify gaps and perceptions of prospective pharmaceutical stimulant substitution treatments (SST).

METHODS

In-depth qualitative interviews were conducted with 86 PWUS in Vancouver, Canada. Thematic analysis focused on experiences of available treatment options for stimulant use and perceptions of prospective SST.

RESULTS

Participants identified how primarily behavioral treatment approaches do not meet the unique needs of PWUS, in contrast with the range of medical treatments available for opioid use disorder. Participants anticipated health and social benefits if they were able to access SST, including avoiding the toxic illicit stimulant supply, reduced engagement in criminalized activities, and greater economic security. Perceptions of prospective SST were informed by knowledge of existing opioid treatments. This led some participants to be unsupportive of SST, citing concerns around agency and highly regulated operational contexts that do not align with the lived realities of stimulant use.

CONCLUSION

Findings demonstrate the need for SST pilot programs in real-world settings and underscore the health and social advantages SST may offer; although drawing on existing opioid treatment models to implement SST pilots may limit success. Thus, any novel treatments for stimulant use must centre the lived realities of PWUS.

Psychosocial interventions for stimulant use disorder

BACKGROUND

Stimulant use disorder is a continuously growing medical and social burden without approved medications available for its treatment. Psychosocial interventions could be a valid approach to help people reduce or cease stimulant consumption. This is an update of a Cochrane review first published in 2016.

OBJECTIVES

To assess the efficacy and safety of psychosocial interventions for stimulant use disorder in adults.

SEARCH METHODS

We searched the Cochrane Drugs and Alcohol Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, three other databases, and two trials registers in September 2023. All searches included non-English language literature. We handsearched the references of topic-related systematic reviews and the included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing any psychosocial intervention with no intervention, treatment as usual (TAU), or a different intervention in adults with stimulant use disorder.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included a total of 64 RCTs (8241 participants). Seventy-three percent of studies included participants with cocaine or crack cocaine use disorder; 3.1% included participants with amphetamine use disorder; 10.9% included participants with methamphetamine use disorder; and 12.5% included participants with any stimulant use disorder. In 18 studies, all participants were in methadone maintenance treatment. In our primary comparison of any psychosocial treatment to no intervention, we included studies which compared a psychosocial intervention plus TAU to TAU alone. In this comparison, 12 studies evaluated cognitive behavioural therapy (CBT), 27 contingency management, three motivational interviewing, one study looked at psychodynamic therapy, and one study evaluated CBT plus contingency management. We also compared any psychosocial intervention to TAU. In this comparison, seven studies evaluated CBT, two contingency management, two motivational interviewing, and one evaluated a combination of CBT plus motivational interviewing. Seven studies compared contingency management reinforcement related to abstinence versus contingency management not related to abstinence. Finally, seven studies compared two different psychosocial approaches. We judged 65.6% of the studies to be at low risk of bias for random sequence generation and 19% at low risk for allocation concealment. Blinding of personnel and participants was not possible for the type of intervention, so we judged all the studies to be at high risk of performance bias for subjective outcomes but at low risk for objective outcomes. We judged 22% of the studies to be at low risk of detection bias for subjective outcomes. We judged most of the studies (69%) to be at low risk of attrition bias. When compared to no intervention, we found that psychosocial treatments: reduce the dropout rate (risk ratio (RR) 0.82, 95% confidence interval (CI) 0.74 to 0.91; 30 studies, 4078 participants; high-certainty evidence); make little to no difference to point abstinence at the end of treatment (RR 1.15, 95% CI 0.94 to 1.41; 12 studies, 1293 participants; high-certainty evidence); make little to no difference to point abstinence at the longest follow-up (RR 1.22, 95% CI 0.91 to 1.62; 9 studies, 1187 participants; high-certainty evidence); probably increase continuous abstinence at the end of treatment (RR 1.89, 95% CI 1.20 to 2.97; 12 studies, 1770 participants; moderate-certainty evidence); may make little to no difference in continuous abstinence at the longest follow-up (RR 1.14, 95% CI 0.89 to 1.46; 4 studies, 295 participants; low-certainty evidence); reduce the frequency of drug intake at the end of treatment (standardised mean difference (SMD) -0.35, 95% CI -0.50 to -0.19; 10 studies, 1215 participants; high-certainty evidence); and increase the longest period of abstinence (SMD 0.54, 95% CI 0.41 to 0.68; 17 studies, 2118 participants; high-certainty evidence). When compared to TAU, we found that psychosocial treatments reduce the dropout rate (RR 0.79, 95% CI 0.65 to 0.97; 9 studies, 735 participants; high-certainty evidence) and may make little to no difference in point abstinence at the end of treatment (RR 1.67, 95% CI 0.64 to 4.31; 1 study, 128 participants; low-certainty evidence). We are uncertain whether they make any difference in point abstinence at the longest follow-up (RR 1.31, 95% CI 0.86 to 1.99; 2 studies, 124 participants; very low-certainty evidence). Compared to TAU, psychosocial treatments may make little to no difference in continuous abstinence at the end of treatment (RR 1.18, 95% CI 0.92 to 1.53; 1 study, 128 participants; low-certainty evidence); probably make little to no difference in the frequency of drug intake at the end of treatment (SMD -1.17, 95% CI -2.81 to 0.47, 4 studies, 479 participants, moderate-certainty evidence); and may make little to no difference in the longest period of abstinence (SMD -0.16, 95% CI -0.54 to 0.21; 1 study, 110 participants; low-certainty evidence). None of the studies for this comparison assessed continuous abstinence at the longest follow-up. Only five studies reported harms related to psychosocial interventions; four of them stated that no adverse events occurred.

AUTHORS' CONCLUSIONS

This review's findings indicate that psychosocial treatments can help people with stimulant use disorder by reducing dropout rates. This conclusion is based on high-certainty evidence from comparisons of psychosocial interventions with both no treatment and TAU. This is an important finding because many people with stimulant use disorders leave treatment prematurely. Stimulant use disorders are chronic, lifelong, relapsing mental disorders, which require substantial therapeutic efforts to achieve abstinence. For those who are not yet able to achieve complete abstinence, retention in treatment may help to reduce the risks associated with stimulant use. In addition, psychosocial interventions reduce stimulant use compared to no treatment, but they may make little to no difference to stimulant use when compared to TAU. The most studied and promising psychosocial approach is contingency management. Relatively few studies explored the other approaches, so we cannot rule out the possibility that the results were imprecise due to small sample sizes.