Double-blind, placebo-controlled trial of selegiline transdermal system (STS) for the treatment of cocaine dependence

Reduced drug use as an alternative valid outcome in individuals with stimulant use disorders: Findings from 13 multisite randomized clinical trials

BACKGROUND AND AIMS

Total abstinence has historically been the goal of treatment for substance use disorders; however, there is a growing recognition of the health benefits associated with reduced use as a harm reduction measure in stimulant use disorders treatment. We aimed to assess the validity of reduced stimulant use as an outcome measure in randomized controlled trials (RCTs) of pharmacological interventions for stimulant use disorder.

DESIGN

We conducted a secondary analysis of a pooled dataset of 13 RCTs.

SETTING AND PARTICIPANTS

Participants were individuals seeking treatment for cocaine or methamphetamine use disorders (N = 2062) in a wide range of treatment facilities in the United States.

MEASUREMENTS

We validated reduced stimulant use against a set of clinical indicators drawn from harmonized measurements, including severity of problems caused by drug use, comorbid depression, global severity of substance use and improvement, severity of drug-seeking behavior, craving and high-risk behaviors, all assessed at the end of the trial, as well as follow-up urine toxicology. A series of mixed effect regression models was conducted to validate reduction in frequency of use against no reduction in use and abstinence.

FINDINGS

More participants reduced frequency of primary drug use than achieved abstinence (18.0% vs. 14.2%, respectively). Reduced use was significantly associated with decreases in craving for the primary drug [60.1%, 95% confidence interval (CI) = 54.3%-64.7%], drug seeking behaviors (41.0%, 95% CI = 36.6%-45.7%), depression severity (39.9%, 95% CI = 30.9%-48.3%), as well as multiple measures of global improvement in psychosocial functioning and severity of drug-related problems, albeit less strongly so than abstinence. Moreover, reduced use was associated with sustained clinical benefit at follow-up, as confirmed by negative urine tests (adjusted odds ratio compared with those with no reduction in use: 0.50, 95% CI = 0.35-0.71).

CONCLUSION

Reduced frequency of stimulant use appears to be associated with meaningful improvement in various clinical indicators of recovery. Assessment of reduced use, in addition to abstinence, could broaden the scope of outcomes measured in randomized controlled trials of stimulant use disorders and facilitate the development of more diverse treatment approaches.

Efficacy and safety of selegiline across different psychiatric disorders: A systematic review and meta-analysis of oral and transdermal formulations

Selegiline is an irreversible, selective type-B monoamine oxidase inhibitor (MAOI) approved for Parkison's disease-oral and major depressive disorder-transdermal formulation) resulting in non-selective MAOI activity at oral doses≥20 mg/day. The present systematic review and meta-analysis appraises the evidence of different formulations/dosages of selegiline across different psychiatric conditions. We inquired PubMed/MEDLINE/Cochrane-Central/WHO-ICTRP/Clarivate-WebOfScience and the Chinese-Electronic-Journal Database from inception to 10/26/2022 for selegiline trials involving psychiatric patients. Random-effects meta-analyses assessed heterogeneity, publication/risk biases, and confidence in the evidence, followed by sensitivity, subgroup, and meta-regression analyses. Co-primary outcomes were: changes in symptom score (standardized mean difference=SMD) and author-defined response (risk ratios=RRs). RRs of adverse events and all-cause discontinuation were secondary and acceptability outcomes, respectively. Systematic-review included 42 studies; meta-analysis, 23. Selegiline outperformed placebo in depressive symptom reduction (SMD=-0.96, 95%C.I.=-1.78, -0.14, k = 10, n = 1,308), depression (RR=1.61, 95%C.I.=1.20, 2.15, k = 9, n = 1,238) and atypical-depression response (RR=2.23, 95%C.I.=1.35, 3.68, k = 3, n = 136). Selegiline failed to outperform the placebo in negative (k = 4) or positive symptoms of schizophrenia (k = 4), attention-deficit-hyperactivity disorder (ADHD) symptoms reduction (k = 2), and smoking abstinence rate (k = 4). Selegiline did not differ from methylphenidate and ADHD scores (k = 2). No significant difference emerged in acceptability, incident diarrhea, headache, dizziness, and nausea RRs, in contrast to xerostomia (RR=1.58, 95%C.I. =1.03, 2.43, k = 6, n = 1,134), insomnia (RR=1.61, 95%C.I.=1.19, 2.17, k = 10, n = 1,768), and application-site reaction for transdermal formulation (RR=1.81, 95%C.I.=1.40, 2.33, k = 6, n = 1,662). Confidence in findings was low/very-low for most outcomes; moderate for depressive symptoms reduction (transdermal). Selegiline proved effective, safe, and well-tolerated for depressive disorders, yet further evidence is warranted about specific psychiatric disorders.

Pharmacological Treatments for Cocaine Craving: What Is the Way Forward? A Systematic Review

BACKGROUND

cocaine craving is a core feature of cocaine use disorder and remains a critical challenge for abstinence and relapse prevention. This review summarizes the anti-craving efficacy of pharmacotherapies tested for cocaine use disorder, in the context of randomized-controlled clinical trials.

OBJECTIVES

we assessed the databases of the U.S. National Library of Medicine, Google Scholar, and PsycINFO, without date restrictions up to August 2022, to identify relevant studies.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

we included double-blinded randomized-controlled trials investigating pharmacotherapies for cocaine craving and/or cocaine use disorder whose outcomes included cocaine craving.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two authors screened studies' titles and abstracts for inclusion, and both read all the included studies. We systematically gathered information on the following aspects of each study: title; author(s); year of publication; sample size; mean age; sample characteristics; study set-ting; whether participants were treatment-seeking; study design; craving measures; study interventions; drop-out rates; and other relevant outcomes.

RESULTS

Overall, we appraised 130 clinical trials, including 8137 participants. We further considered the drugs from the studies that scored equal to or greater than six points in the quality assessment. There was a correlation between craving and cocaine use outcomes (self-reports, timeline follow-back or urinary benzoylecgonine) in the vast majority of studies. In the short-term treatment, acute phenylalanine-tyrosine depletion, clonidine, fenfluramine, meta-chlorophenylpiperazine (m-CPP) and mecamylamine presented promising effects. In the long term, amphetamine, biperiden, carbamazepine, lisdexamfetamine, lorcaserin, methamphetamine, mirtazapine, pioglitazone, progesterone, guanfacine, levodopa, nefazodone presented promising anti-craving effects. Unfortunately, the highly tested medications were not successful in most of the trials, as follows: propranolol in the short term; amantadine, aripiprazole, bromocriptine, citicoline, ketamine, modafinil, olanzapine, topiramate in the long term. The remaining 52 medications had no positive anti-craving outcomes.

LIMITATIONS

Our review was limited by high heterogeneity of craving assessments across the studies and by a great range of pharmacotherapies. Further, the majority of the studies considered abstinence and retention in treatment as the main outcomes, whereas craving was a secondary outcome and some of the studies evaluated patients with cocaine use disorder with comorbidities such as opioid or alcohol use disorder, schizophrenia, bipolar disorder or attention deficit hyperactivity. Lastly, most of the studies also included non-pharmacological treatments, such as counseling or psychotherapy.

CONCLUSIONS

There is a direct association between craving and cocaine use, underscoring craving as an important treatment target for promoting abstinence among persons with cocaine use disorder. Clonidine, fenfluramine and m-CPP showed to be promising medications for cocaine craving in the short-term treatment, and amphetamine, biperiden, carbamazepine, lisdexamfetamine, lorcaserin, methamphetamine, mirtazapine, pioglitazone, progesterone, guanfacine, levodopa, nefazodone in the long-term treatment.

Comparison of Treatments for Cocaine Use Disorder Among Adults: A Systematic Review and Meta-analysis

IMPORTANCE

In the US and the United Kingdom, cocaine use is the second leading cause of illicit drug overdose death. Psychosocial treatments for cocaine use disorder are limited, and no pharmacotherapy is approved for use in the US or Europe.

OBJECTIVE

To compare treatments for active cocaine use among adults.

DATA SOURCES

PubMed and the Cochrane Database of Systematic Reviews were searched for clinical trials published between December 31, 1995, and December 31, 2017.

STUDY SELECTION

This meta-analysis was registered on Covidence.org (study 8731) on December 31, 2015. Clinical trials were included if they (1) had the term cocaine in the article title; (2) were published between December 31, 1995, and December 31, 2017; (3) were written in English; (4) enrolled outpatients 18 years or older with active cocaine use at baseline; and (5) reported treatment group size, treatment duration, retention rates, and urinalysis results for the presence of cocaine metabolites. A study was excluded if (1) more than 25% of participants were not active cocaine users or more than 80% of participants had negative test results for the presence of cocaine metabolites at baseline and (2) it reported only pooled urinalysis results indicating the presence of multiple substances and did not report the specific proportion of positive test results for cocaine metabolites. Multiple reviewers reached criteria consensus. Of 831 records screened, 157 studies (18.9%) met selection criteria and were included in the analysis.

DATA EXTRACTION AND SYNTHESIS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline. Search results were imported from PubMed XML into Covidence.org then Microsoft Excel. Data extraction was completed in 2 iterations to ensure fidelity. Analyses included a multilevel random-effects model, a multilevel mixed-effects meta-regression model, and sensitivity analyses. Treatments were clustered into 11 categories (psychotherapy, contingency management programs, placebo, opioids, psychostimulants, anticonvulsants, dopamine agonists, antidepressants, antipsychotics, miscellaneous medications, and other therapies). Missing data were imputed using multiple imputation by chained equations. The significance threshold for all analyses was P = .05. Data were analyzed using the metafor and mice packages in R software, version 3.3.2 (R Foundation for Statistical Computing). Data were analyzed from January 1, 2018, to February 28, 2021.

MAIN OUTCOMES AND MEASURES

The primary outcome was the intention-to-treat logarithm of the odds ratio (OR) of having a negative urinalysis result for the presence of cocaine metabolites at the end of each treatment period compared with baseline. The hypothesis, which was formulated after data collection, was that no treatment category would have a significant association with objective reductions in cocaine use.

RESULTS

A total of 157 studies comprising 402 treatment groups and 15 842 participants were included. Excluding other therapies, the largest treatment groups across all studies were psychotherapy (mean [SD] number of participants, 40.04 [36.88]) and contingency management programs (mean [SD] number of participants, 37.51 [25.51]). Only contingency management programs were significantly associated with an increased likelihood of having a negative test result for the presence of cocaine (OR, 2.13; 95% CI, 1.62-2.80), and this association remained significant in all sensitivity analyses.

CONCLUSIONS AND RELEVANCE

In this meta-analysis, contingency management programs were associated with reductions in cocaine use among adults. Research efforts and policies that align with this treatment modality may benefit those who actively use cocaine and attenuate societal burdens.

Candidate pharmacological treatments for substance use disorder and suicide identified by gene co-expression network-based drug repositioning

Patients with substance use disorders (SUD) are at high risk to die by suicide. So far, the neurobiology of the suicide-SUD association has not been elucidated. This study aimed to identify potential pharmacological targets among hub genes from brain gene co-expression networks of individuals with SUD in a suicidal and non-suicidal context. Post-mortem samples from the prefrontal cortex of 79 individuals were analyzed. Individuals were classified into the following groups: suicides with SUD (n = 28), suicides without SUD (n = 23), nonsuicides with SUD (n = 9), nonsuicides without SUD (n = 19). Gene expression profiles were evaluated with the Illumina HumanHT-12 v4 array. Co-expression networks were constructed in WGCNA using the differentially expressed genes found in the comparisons: (a) suicides with and without SUD and (b) nonsuicides with and without SUD. Hub genes were selected for drug-gene interaction testing in the DGIdb database. Among drugs interacting with hub genes in suicides we found MAOA inhibitors and dextromethorphan. In the nonsuicide individuals, we found interactions with eglumegad and antipsychotics (olanzapine, clozapine, loxapine). Modafinil was found to interact with genes in both suicides and nonsuicides. These drugs represent possible candidate treatments for patients with SUD with and without suicidal behavior and their study in each context is encouraged.

Selegiline: a molecule with innovative potential

Monoamine oxidase B (MAO-B) inhibitors have an established role in the treatment of Parkinson's disease as monotherapy or adjuvant to levodopa. Two major recognitions were required for their introduction into this therapeutic field. The first was the elucidation of the novel pharmacological properties of selegiline as a selective MAO-B inhibitor by Knoll and Magyar and the original idea of Riederer and Youdim, supported by Birkmayer, to explore its effect in parkinsonian patients with on-off phases. In the 1960s, MAO inhibitors were mainly studied as potential antidepressants, but Birkmayer found that combined use of levodopa and various MAO inhibitors improved akinesia in Parkinson's disease. However, the serious side effects of the first non-selective MAO inhibitors prevented their further use. Later studies demonstrated that MAO-B, mainly located in glial cells, is important for dopamine metabolism in the brain. Recently, cell and molecular studies revealed interesting properties of selegiline opening new possibilities for neuroprotective mechanisms and a disease-modifying effect of MAO-B inhibitors.

Linear-rank testing of a non-binary, responder-analysis, efficacy score to evaluate pharmacotherapies for substance use disorders

The design of pharmacological trials for management of substance use disorders is shifting toward outcomes of successful individual-level behavior (abstinence or no heavy use). While binary success/failure analyses are common, McCann and Li (CNS Neurosci Ther 2012; 18: 414-418) introduced "number of beyond-threshold weeks of success" (NOBWOS) scores to avoid dichotomized outcomes. NOBWOS scoring employs an efficacy "hurdle" with values reflecting duration of success. Here, we evaluate NOBWOS scores rigorously. Formal analysis of mathematical structure of NOBWOS scores is followed by simulation studies spanning diverse conditions to assess operating characteristics of five linear-rank tests on NOBWOS scores. Simulations include assessment of Fisher's exact test applied to hurdle component. On average, statistical power was approximately equal for five linear-rank tests. Under none of conditions examined did Fisher's exact test exhibit greater statistical power than any of the linear-rank tests. These linear-rank tests provide good Type I and Type II error control for comparing distributions of NOBWOS scores between groups (e.g. active vs. placebo). All methods were applied to re-analyses of data from four clinical trials of differing lengths and substances of abuse. These linear-rank tests agreed across all trials in rejecting (or not) their null (equality of distributions) at ≤ 0.05.

Inhibitors of MAO-A and MAO-B in Psychiatry and Neurology

Inhibitors of MAO-A and MAO-B are in clinical use for the treatment of psychiatric and neurological disorders respectively. Elucidation of the molecular structure of the active sites of the enzymes has enabled a precise determination of the way in which substrates and inhibitor molecules are metabolized, or inhibit metabolism of substrates, respectively. Despite the knowledge of the strong antidepressant efficacy of irreversible MAO inhibitors, their clinical use has been limited by their side effect of potentiation of the cardiovascular effects of dietary amines (“cheese effect”). A number of reversible MAO-A inhibitors which are devoid of cheese effect have been described in the literature, but only one, moclobemide, is currently in clinical use. The irreversible inhibitors of MAO-B, selegiline and rasagiline, are used clinically in treatment of Parkinson's disease, and a recently introduced reversible MAO-B inhibitor, safinamide, has also been found efficacious. Modification of the pharmacokinetic characteristics of selegiline by transdermal administration has led to the development of a new drug form for treatment of depression. The clinical potential of MAO inhibitors together with detailed knowledge of the enzyme's binding site structure should lead to future developments with these drugs.

Psychostimulant drugs for cocaine dependence

BACKGROUND

Cocaine dependence is a severe disorder for which no medication has been approved. Like opioids for heroin dependence, replacement therapy with psychostimulants could be an effective therapy for treatment.

OBJECTIVES

To assess the effects of psychostimulants for cocaine abuse and dependence. Specific outcomes include sustained cocaine abstinence and retention in treatment. We also studied the influence of type of drug and comorbid disorders on psychostimulant efficacy.

SEARCH METHODS

This is an update of the review previously published in 2010. For this updated review, we searched the Cochrane Drugs and Alcohol Group Trials Register, CENTRAL, MEDLINE, Embase and PsycINFO up to 15 February 2016. We handsearched references of obtained articles and consulted experts in the field.

SELECTION CRITERIA

We included randomised parallel group controlled clinical trials comparing the efficacy of a psychostimulant drug versus placebo.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 26 studies involving 2366 participants. The included studies assessed nine drugs: bupropion, dexamphetamine, lisdexamfetamine, methylphenidate, modafinil, mazindol, methamphetamine, mixed amphetamine salts and selegiline. We did not consider any study to be at low risk of bias for all domains included in the Cochrane 'Risk of bias' tool. Attrition bias was the most frequently suspected potential source of bias of the included studies. We found very low quality evidence that psychostimulants improved sustained cocaine abstinence (risk ratio (RR) 1.36, 95% confidence interval (CI) 1.05 to 1.77, P = 0.02), but they did not reduce cocaine use (standardised mean difference (SMD) 0.16, 95% CI -0.02 to 0.33) among participants who continued to use it. Furthermore, we found moderate quality evidence that psychostimulants did not improve retention in treatment (RR 1.00, 95% CI 0.93 to 1.06). The proportion of adverse event-induced dropouts and cardiovascular adverse event-induced dropouts was similar for psychostimulants and placebo (RD 0.00, 95% CI -0.01 to 0.01; RD 0.00, 95% CI -0.02 to 0.01, respectively). When we included the type of drug as a moderating variable, the proportion of patients achieving sustained cocaine abstinence was higher with bupropion and dexamphetamine than with placebo. Psychostimulants also appeared to increase the proportion of patients achieving sustained cocaine and heroin abstinence amongst methadone-maintained, dual heroin-cocaine addicts. Retention to treatment was low, though, so our results may be compromised by attrition bias. We found no evidence of publication bias.

AUTHORS' CONCLUSIONS

This review found mixed results. Psychostimulants improved cocaine abstinence compared to placebo in some analyses but did not improve treatment retention. Since treatment dropout was high, we cannot rule out the possibility that these results were influenced by attrition bias. Existing evidence does not clearly demonstrate the efficacy of any pharmacological treatment for cocaine dependence, but substitution treatment with psychostimulants appears promising and deserves further investigation.

Sigma-1 receptor mediates cocaine-induced transcriptional regulation by recruiting chromatin-remodeling factors at the nuclear envelope

The sigma-1 receptor (Sig-1R) chaperone at the endoplasmic reticulum (ER) plays important roles in cellular regulation. Here we found a new function of Sig-1R, in that it translocates from the ER to the nuclear envelope (NE) to recruit chromatin-remodeling molecules and regulate the gene transcription thereof. Sig-1Rs mainly reside at the ER-mitochondrion interface. However, on stimulation by agonists such as cocaine, Sig-1Rs translocate from ER to the NE, where Sig-1Rs bind NE protein emerin and recruit chromatin-remodeling molecules, including lamin A/C, barrier-to-autointegration factor (BAF), and histone deacetylase (HDAC), to form a complex with the gene repressor specific protein 3 (Sp3). Knockdown of Sig-1Rs attenuates the complex formation. Cocaine was found to suppress the gene expression of monoamine oxidase B (MAOB) in the brain of wild-type but not Sig-1R knockout mouse. A single dose of cocaine (20 mg/kg) in rats suppresses the level of MAOB at nuclear accumbens without affecting the level of dopamine transporter. Daily injections of cocaine in rats caused behavioral sensitization. Withdrawal from cocaine in cocaine-sensitized rats induced an apparent time-dependent rebound of the MAOB protein level to about 200% over control on day 14 after withdrawal. Treatment of cocaine-withdrawn rats with the MAOB inhibitor deprenyl completely alleviated the behavioral sensitization to cocaine. Our results demonstrate a role of Sig-1R in transcriptional regulation and suggest cocaine may work through this newly discovered genomic action to achieve its addictive action. Results also suggest the MAOB inhibitor deprenyl as a therapeutic agent to block certain actions of cocaine during withdrawal.

Psychostimulants: Basic and Clinical Pharmacology

Substance use disorder, and particularly psychostimulant use disorder, has considerable socioeconomic burden globally. The psychostimulants include several chemical classes, being derivatives of benzoylecgonine, phenethylamine, phenylpropanolamine, or aminoaryloxazoline. Psychostimulant drugs activate the brain reward pathways of the mesoaccumbal system, and continued use leads to persistent neuroplastic and dysfunctional changes of a variety of structures involved in learning and memory, habit-forming learning, salience attribution, and inhibitory control. There are a variety of neurochemical and neurobehavioral changes in psychostimulant addiction, for example, dopaminergic, glutamatergic, serotonergic (5-HT-ergic), and γ-amino butyric acid (GABA) changes have all noted. In this chapter, we will review pharmacological changes associated with psychostimulant use and abuse in humans and animals, and on the basis of the best characterized and most widely abused psychostimulants (amphetamines, cocaine) discuss why use transitions into abuse and review basic science and clinical strategies that might assist in treating psychostimulant abuse.

Update on the pharmacology of selective inhibitors of MAO-A and MAO-B: focus on modulation of CNS monoamine neurotransmitter release

Inhibitors of monoamine oxidase (MAO) were initially used in medicine following the discovery of their antidepressant action. Subsequently their ability to potentiate the effects of an indirectly-acting sympathomimetic amine such as tyramine was discovered, leading to their limitation in clinical use, except for cases of treatment-resistant depression. More recently, the understanding that: a) potentiation of indirectly-acting sympathomimetic amines is caused by inhibitors of MAO-A but not by inhibitors of MAO-B, and b) that reversible inhibitors of MAO-A cause minimal tyramine potentiation, has led to their re-introduction to clinical use for treatment of depression (reversible MAO-A inhibitors and new dose form MAO-B inhibitor) and treatment of Parkinson's disease (MAO-B inhibitors). The profound neuroprotective properties of propargyl-based inhibitors of MAO-B in preclinical experiments have drawn attention to the possibility of employing these drugs for their neuroprotective effect in neurodegenerative diseases, and have raised the question of the involvement of the MAO-mediated reaction as a source of reactive free radicals. Despite the long-standing history of MAO inhibitors in medicine, the way in which they affect neuronal release of monoamine neurotransmitters is still poorly understood. In recent years, the detailed chemical structure of MAO-B and MAO-A has become available, providing new possibilities for synthesis of mechanism-based inhibitors. This review describes the latest advances in understanding the way in which MAO inhibitors affect the release of the monoamine neurotransmitters dopamine, noradrenaline and serotonin (5-HT) in the CNS, with an accent on the importance of these effects for the clinical actions of the drugs.

Pharmacotherapeutics for substance-use disorders: a focus on dopaminergic medications

INTRODUCTION

Illicit substance-use is a substantial public health concern, contributing over $150 billion in costs annually to Americans. A complex disease, a substance-use disorder affects neural circuits involved in reinforcement, motivation, learning and memory, and inhibitory control.

AREAS COVERED

The modulatory influence of dopamine in mesocorticolimbic circuits contributes to encoding the primary reinforcing effects of substances and numerous studies suggest that aberrant signaling within these circuits contributes to the development of a substance-use disorder in some individuals. Decades of research focused on the clinical development of medications that directly target dopamine receptors has led to recent studies of agonist-like dopaminergic treatments for stimulant-use disorders and, more recently, cannabis-use disorder. Human studies evaluating the efficacy of dopaminergic agonist-like medications to reduce reinforcing effects and substance-use provide some insight into the design of future pharmacotherapy trials. A search of PubMed using specific brain regions, medications, and/or the terms 'dopamine', 'cognition', 'reinforcement', 'cocaine', 'methamphetamine', 'amphetamine', 'cannabis', 'treatment/pharmacotherapy', 'addiction/abuse/dependence' identified articles relevant to this review.

EXPERT OPINION

Conceptualization of substance-use disorders and their treatment continues to evolve. Current efforts increasingly focus on a strategy fostering combination pharmacotherapies that target multiple neurotransmitter systems.

Modification of cocaine self-administration by buspirone (buspar®): potential involvement of D3 and D4 dopamine receptors

Converging lines of evidence indicate that elevations in synaptic dopamine levels play a pivotal role in the reinforcing effects of cocaine, which are associated with its abuse liability. This evidence has led to the exploration of dopamine receptor blockers as pharmacotherapy for cocaine addiction. While neither D1 nor D2 receptor antagonists have proven effective, medications acting at two other potential targets, D3 and D4 receptors, have yet to be explored for this indication in the clinic. Buspirone, a 5-HT1A partial agonist approved for the treatment of anxiety, has been reported to also bind with high affinity to D3 and D4 receptors. In view of this biochemical profile, the present research was conducted to examine both the functional effects of buspirone on these receptors and, in non-human primates, its ability to modify the reinforcing effects of i.v. cocaine in a behaviourally selective manner. Radioligand binding studies confirmed that buspirone binds with high affinity to recombinant human D3 and D4 receptors (∼98 and ∼29 nm respectively). Live cell functional assays also revealed that buspirone, and its metabolites, function as antagonists at both D3 and D4 receptors. In behavioural studies, doses of buspirone that had inconsistent effects on food-maintained responding (0.1 or 0.3 mg/kg i.m.) produced a marked downward shift in the dose-effect function for cocaine-maintained behaviour, reflecting substantial decreases in self-administration of one or more unit doses of i.v. cocaine in each subject. These results support the further evaluation of buspirone as a candidate medication for the management of cocaine addiction.

Measuring Outcome in the Treatment of Cocaine Dependence

BACKGROUND

Little in known about the extent to which outcome measures used in studies of the treatment of cocaine dependence are associated with longer-term use and with broader measures of clinical improvement. The current study examined reductions in use, and abstinence-oriented measures, in relation to functioning and longer-term clinical benefits in the treatment of cocaine dependence.

METHODS

Overall drug use, cocaine use, and functioning in a number of addiction-related domains for 487 patients diagnosed with DSM-IV cocaine dependence and treated with one of four psychosocial interventions in the NIDA Cocaine Collaborative Treatment Study were assessed monthly during 6 months of treatment and at 9, 12, 15, and 18 month follow-up.

RESULTS

Measures of during-treatment reduction in use were moderately correlated with drug and cocaine use measures 12 months, but showed non-significant or small correlations with measures of functioning at 12 months. Highest correlations were evident for abstinence measures (maximum consecutive days abstinence and completely abstinent) during treatment in relation to sustained (3 month) abstinence at 12 months. Latent class analysis of patterns of change over time revealed that most patients initially (months 1 to 4 of treatment) either became abstinent immediately or continued to use every month. Over the couse of follow-up, patients either maintained abstinence or used regularly - intermittent use was less common.

CONCLUSIONS

There were generally small associations between various measures of cocaine use and longer-term clinical benefits, other than abstinence was associated with continued abstinence. No one method of measuring outcome of treatment of cocaine dependence appears superior to others.

Developments in harmine pharmacology--implications for ayahuasca use and drug-dependence treatment

Ayahuasca is a hallucinogenic botanical mixture originating in the Amazon area where it is used ritually, but is now being taken globally. The 2 main constituents of ayahuasca are N,N-dimethyltryptamine (DMT), a hallucinogen, and harmine, a monoamine oxidase inhibitor (MAOI) which attenuates the breakdown of DMT, which would otherwise be broken down very quickly after oral consumption. Recent developments in ayahuasca use include the sale of these compounds on the internet and the substitution of related botanical (anahuasca) or synthetic (pharmahuasca) compounds to achieve the same desired hallucinogenic effects. One intriguing result of ayahuasca use appears to be improved mental health and a reduction in recidivism to alternate (alcohol, cocaine) drug use. In this review we discuss the pharmacology of ayahuasca, with a focus on harmine, and suggest pharmacological mechanisms for the putative reduction in recidivism to alcohol and cocaine misuse. These pharmacological mechanisms include MAOI, effects at 5-HT(2A) and imidazoline receptors and inhibition of dual-specificity tyrosine-phosphorylation regulated kinase 1A (DYRK1A) and the dopamine transporter. We also speculate on the therapeutic potential of harmine in other CNS conditions.

Psychostimulant treatment of cocaine dependence

The use of stimulant medications for the treatment of cocaine dependence is an evolving scientific line of research. To date, the most promising results are with the higher-potency medications, the amphetamine analogues, or a combination of a dopaminergic medication with a contingency management behavioral intervention. The development of effective pharmacotherapies for opioid and nicotine dependence using an agonist replacement approach suggests that these promising findings needs to continue to be vigorously investigated. In clinical trial reports, there are very few instances of cardiovascular adverse events, which suggests that for well-selected patients with cocaine dependence, stimulant replacement therapy can be safe. However, clinical trial eligibility criteria excludes most high-risk patients from participating, and introducing stimulant substitution to the wider treatment community would likely expose more vulnerable patients to the medical risks associated with stimulant treatment while using cocaine. As treatment development research moves forward, attention must be paid to helping clinicians select patients who are most likely to benefit from stimulant substitution treatment and how to identify those at risk. An additional concern with the use of stimulant medication treatment of cocaine dependence is prescribing controlled substances for patients with active substance use disorders. Again, within a clinical trial, medication supplies are monitored and distributed carefully in small quantities. In a community setting, misuse or diversion will be risks associated with prescribing controlled substances to patients with addictive disorders, but therapeutic strategies for monitoring and limiting that risk can be implemented. Psychostimulant pharmacotherapy is a promising line of research for the treatment of cocaine dependence, a condition for which no effective pharmacotherapy has been identified. Further research is required to confirm positive results from single-site trials, in particular the study of amphetamines as a treatment for cocaine dependence. As this literature evolves, strategies to manage the risk of prescribing controlled substances to patients with addictive disorders need to be tested and refined. Biases against using controlled substances as a treatment for cocaine dependence should be challenged, much in the way the use of agonist treatment transformed the treatment of opioid dependence despite initial resistance from the field.

Antidepressants for cocaine dependence and problematic cocaine use

BACKGROUND

Cocaine dependence is a disorder for which no pharmacological treatment of proven efficacy exists, advances in the neurobiology could guide future medication development.

OBJECTIVES

To investigate the efficacy and acceptability of antidepressants alone or in combination with any psychosocial intervention for the treatment of cocaine dependence and problematic cocaine use.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, EMBASE and CINAHL in July 2011 and researchers for unpublished trials.

SELECTION CRITERIA

Randomised clinical trials comparing antidepressants alone or associated with psychosocial intervention with placebo, no treatment, other pharmacological or psychosocial interventions.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

37 studies were included in the review (3551 participants).Antidepressants versus placebo: results for dropouts did not show evidence of difference, 31 studies, 2819 participants, RR 1.03 (Cl 95% 0.93 to 1.14). Looking at Abstinence from cocaine use, even though not statistically significant, the difference shown by the analysis in the three-weeks abstinence rate was in favour of antidepressants (eight studies, 942 participants, RR 1.22 (Cl 95% 0.99 to 1.51)). Considering only studies involving tricyclics, five studies, 367 participants, or only desipramine, four studies, 254 participants, the evidence was in favour of antidepressants. However, selecting only studies with operationally defined diagnostic criteria, statistical significance favouring antidepressants, as well as the trend for significance shown by the full sample, disappeared. Looking at safety issues, the results did not show evidence of differences (number of patients withdrawn for medical reasons, thirteen studies, 1396 participants, RR 1.39 (Cl 95% 0.91 to 2.12)). Subgroup analysis considering length of the trial, associated opioid dependence or associated psychosocial interventions as confounding factors, failed in showing consistent and statistically significant differences in favour of antidepressants.Antidepressants versus other drugs: Comparing antidepressants with dopamine agonists or with anticonvulsants, no evidence of differences was shown on dropouts and on other outcomes (abstinence from cocaine use, adverse events).

AUTHORS' CONCLUSIONS

At the current stage of evidence data do not support the efficacy of antidepressants in the treatment of cocaine abuse/dependence. Partially positive results obtained on secondary outcome measures, such as depression severity, do not seem to be associated with an effect on direct indicators of cocaine abuse/dependence. Antidepressants cannot be considered a mainstay of treatment for unselected cocaine abusers/dependents.

Selegiline transdermal system (STS) as an aid for smoking cessation

INTRODUCTION

This study examined the efficacy and safety of selegiline transdermal system (STS) and brief repeated behavioral intervention (BRBI) for smoking cessation in heavy smokers. We hypothesized that the quit rate of subjects who received STS and BRBI would be significantly greater than that of those who received placebo patch and BRBI.

METHODS

This was a double-blind, placebo-controlled parallel-group study in which 246 men and women were randomized to receive either STS (n = 121) or placebo patch (n =125) for 9 weeks. Recruitment targeted heavy smokers, defined as individuals with self-reported use of ≥15 cigarettes/day in the 30 days prior to enrollment, who had smoked cigarettes for the past 5 years, and had an expired CO level ≥9 ppm during screening.

RESULTS

Although STS was well tolerated, the overall results indicated that STS with BRBI was not more effective than placebo plus BRBI for smoking cessation (p = .58).

CONCLUSIONS

The results are discussed in relation to interventions for heavy smokers. Although 2 trials using oral selegiline both showed trends toward improved abstinence, these results indicate that STS with BRBI was not an effective aid for smoking cessation at the end of treatment (10 weeks), 14, or 26 weeks.

Efficacy of psychostimulant drugs for cocaine dependence

BACKGROUND

Cocaine dependence is an increasingly prevalent disorder for which no medication is approved yet. Likewise opioid for heroin dependence, replacement therapy with psychostimulant could be efficacious for cocaine dependence.

OBJECTIVES

To ascertain the efficacy of psychostimulants for cocaine dependence on cocaine use, sustained cocaine abstinence and retention in treatment. The influence of type of drug, comorbid disorders and clinical trial reporting quality over psychostimulants efficacy has also been studied.

SEARCH STRATEGY

MEDLINE, EMBASE, PsycINFO, CENTRAL, references of obtained articles and experts in the field.

SELECTION CRITERIA

Randomized parallel group controlled clinical trials comparing the efficacy of a psychostimulant against placebo have been included.

DATA COLLECTION AND ANALYSIS

Two authors evaluated and extracted data. The Relative Risk (RR) was used to assess dichotomous outcomes except for adverse event (AE) induced dropouts for which the risk difference (RD) was preferred. The Standardized Mean Difference (SMD) was used to assess continuous outcomes. To determine the influence of moderating variables, a stratified analysis was conducted. Funnel plots were drawn to investigate the possibility of publication bias.

MAIN RESULTS

Sixteen studies have been included, which have enrolled 1,345 patients. Seven drugs with psychostimulant effect or metabolized to a psychostimulant have been investigated: bupropion, dexamphetamine, methylphenidate, modafinil, mazindol, methamphetamine and selegiline. Psychostimulants did not reduce cocaine use (SMD 0.11, 95%CI: -0.07 to 0.29), showed a statistical trend over improving sustained cocaine abstinence (RR 1.41, 95%CI: 0.98 to 2.02, p=0.07) and did not improve retention in treatment (RR 0.97, 95%CI: 0.89 to 1.05). The proportion of AE induced dropouts was similar for psychostimulants and placebo (RD 0.01, 95%CI: -0.02 to 0.03). When the type of drug was included as a moderating variable, it was shown that the proportion of patients achieving sustained cocaine abstinence was higher with bupropion and dextroamphetamine, and also with modafinil, at a statistical trend of significance, than with placebo. Nevertheless, no studied drug was efficacious on any of the remaining outcomes. Besides, psychostimulants appeared to increase the proportion of patients achieving sustained cocaine and heroin abstinence amongst methadone maintained dual heroin-cocaine addicts. The main findings did not seem to be influenced by clinical trial reporting quality. No evidence of publication bias was found.

AUTHORS' CONCLUSIONS

This review found mixed results, therefore evidence of the efficacy of psychostimulants for cocaine dependence is inconclusive. Nevertheless promising results exist for methadone maintained dual heroin-cocaine addicts and for some specific drugs such as dexamphetamine and bupropion.

A phase 1 trial of pharmacologic interactions between transdermal selegiline and a 4-hour cocaine infusion

Background

The selective MAO-B inhibitor selegiline has been evaluated in clinical trials as a potential medication for the treatment of cocaine dependence. This study evaluated the safety of and pharmacologic interactions between 7 days of transdermal selegiline dosed with patches (Selegiline Transdermal System, STS) that deliver 6 mg/24 hours and 2.5 mg/kg of cocaine administered over 4 hours.

Methods

Twelve nondependent cocaine-experienced subjects received deuterium-labeled cocaine-d5 intravenously (IV) 0.5 mg/kg over 10 minutes followed by 2 mg/kg over 4 hours before and after one week of transdermal selegiline 6 mg/24 hours. Plasma and urine were collected for analysis of selegiline, cocaine, catecholamine and metabolite concentrations. Pharmacodynamic measures were obtained.

Results

Selegiline did not change cocaine pharmacokinetic parameters. Selegiline administration increased phenylethylamine (PEA) urinary excretion and decreased urinary MHPG-sulfate concentration after cocaine when compared to cocaine alone. No serious adverse effects occurred with the combination of selegiline and cocaine, and cocaine-induced physiological effects were unchanged after selegiline. Only 1 peak subjective cocaine effects rating changed, and only a few subjective ratings decreased across time after selegiline.

Conclusion

No pharmacological interaction occurred between selegiline and a substantial dose of intravenous cocaine, suggesting the combination will be safe in pharmacotherapy trials. Selegiline produced few changes in subjective response to the cocaine challenge perhaps because of some psychoactive neurotransmitters changing in opposite directions.

Chronic treatment with monoamine oxidase-B inhibitors decreases cocaine reward in mice

RATIONALE AND OBJECTIVE

Whether monoamine oxidase inhibitors (MAOIs) can be used to suppress the reinforcing effect of cocaine remains unknown. This study was undertaken to examine effects of a long-term dosing regimen with selective MAOIs on cocaine and food reward.

MATERIALS AND METHODS

Since single dose of clorgyline (2 mg/kg), deprenyl (1 mg/kg), and pargyline (10 mg/kg) did not acutely affect mouse locomotor activity, these doses were chosen to treat the male C57BL/6j mice on a daily basis.

RESULTS

Fourteen consecutive days of pretreatments with clorgyline, deprenyl, or pargyline (one injection per day) did not affect natural reward-supported operant behavior, since acquisition of the lever pressing responses for food pellets under an FR-1 protocol did not differ among these drug- and saline-treated mice. Likewise, 24 consecutive days of pretreatments with clorgyline did not alter acquisition of the cocaine (0.3 mg/kg per infusion)-supported operant responses under an FR-1 protocol. In contrast, 24 days of pretreatments with deprenyl and pargyline abolished the cocaine-supported operant responses under a similar protocol. Twenty-four days of clorgyline treatment enhanced serotonin contents in striatum, nucleus accumbens, and frontal cortex. Frontal cortical 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacidic acid concentrations were decreased following 24 days of pretreatments with deprenyl and pargyline. These changes were not evident in mice pretreated with clorgyline.

CONCLUSIONS

We suggest that long-term treatments with MAO-B inhibitors may decrease cocaine-supported operant responses in cocaine-naïve mice by selectively decreasing frontal cortical metabolism of dopamine and serotonin.

Use of stimulants to treat cocaine and methamphetamine abuse

The concept of using stimulants to treat cocaine and methamphetamine dependence is largely based on the "replacement" therapy model that has shown efficacy for treating nicotine and opiate dependence. Although results have been mixed, some evidence supports using stimulant medication to reduce cocaine use. There are not enough data to date to determine the efficacy of stimulants for methamphetamine dependence. Drawbacks of stimulants as treatments include the potential for abuse of the treatment, which necessitates careful screening and monitoring of patients. Possible reasons for efficacy of stimulants include enhancement of monoamine function dysregulated by chronic cocaine or methamphetamine use. Newer medications that enhance dopamine function but lack the abuse potential of older stimulants are being studied. It is hoped that these medications will provide safe, effective treatment for cocaine and methamphetamine dependence, but more research on this topic is needed.

Controversies in translational research: drug self-administration

RATIONALE

Laboratory animal and human models of drug self-administration are used to evaluate potential pharmacotherapies for drug abuse, yet the utility of these models in predicting clinically useful medications is variable.

OBJECTIVE

The objective of this study was to track how antagonist, agonist, and partial agonist medication approaches influence heroin and cocaine self-administration by rodents, non-human primates, and humans and to compare these results to clinical outcomes.

RESULTS

Across species, heroin self-administration was decreased by all three medication approaches, paralleling their demonstrated clinical utility. The heroin data emphasize the importance of assessing a medication's abuse liability preclinically to predict medication abuse and compliance and of considering subject characteristics (e.g., opioid dependence) when interpreting medication effects. For cocaine, the effects of ecopipam, modafinil, and aripiprazole were consistent in the laboratory and clinic, provided that the medications were administered repeatedly before self-administration sessions. Modafinil attenuated cocaine's reinforcing effects in the human laboratory and improved treatment outcome, while ecopipam and aripiprazole increased the reinforcing effects of cocaine and do not appear promising in the clinic.

CONCLUSIONS

The self-administration model has reliably identified medications to treat opioid dependence, and the recent data with modafinil suggest that the human laboratory model also identifies medications to treat cocaine dependence. There have been numerous false positives when subjective effects are the primary outcome measure, but not when self-administration is the outcome. Factors relevant to the predictive validity of self-administration procedures include medication maintenance and the concurrent assessment of a range of behaviors to determine abuse liability and the specificity of effect.

Selegiline transdermal system in the treatment of depressive disorders

Selegiline is a selective irreversible inhibitor of monoamine oxidase (MAO)-B during low-dose oral treatment. Additional MAO-A inhibition occurs in higher dose ranges. Selegiline transdermal system (STS) shows a more potent MAO inhibition in comparison with orally administered selegiline, and at minimum doses of 20 mg/20 cm2 patch delivering 6 mg/24 h, no dietary restrictions, including low-tyramine food, are necessary. While oral selegiline has been used for years in the treatment of Parkinson’s disease, the US FDA recently approved the STS for use in treating major depression. Data from three randomized controlled trials showed a significantly better efficacy of STS in the treatment of unipolar major depression in comparison with placebo during 6–8 weeks of treatment. In addition, one long-term randomized controlled trial demonstrated the efficacy of the STS in relapse prevention of unipolar depression over 1 year. A total number of 515 depressed patients received STS during these studies. The tolerability profile of STS without dietary restrictions was excellent. The only side effects that were more frequent than with placebo were application-site reactions. No change in vital parameters and no hypertensive crisis have been recorded. Comparative studies including treatment with established antidepressants and the investigation of bipolar depressed patients and of specific patient subgroups (e.g., anergic and atypical depression) have to follow. The combination of the well-known effectiveness of irreversible MAO inhibitors with a good tolerability profile and a new pharmaceutical form, possibly enhancing compliance, represents a promising further expansion of the pharmacotherapeutic repertoire in the treatment of depression.

Selegiline transdermal system: current awareness and promise

Many monoamine oxidase inhibitors (MAOIs) have been used to treat major depressive disorder (MDD). However, the prescription of MAOIs has decreased considerably as a result of side effects such as tyramine-induced hypertensive crisis, which is also known as the 'Cheese Effect'. The drug delivery system itself can affect the bioavailability of certain drugs, which might influence the efficacy and tolerability of medications, as well as improve the compliance and reduce the incidence of recurrence and relapse. Therefore, there is a need for advanced drug delivery techniques that can evade the potentially hazardous toxic effects of the parent compound, including extended-release oral, cutaneous, intravesical and intravaginal routes, etc. In this context, the selegiline transdermal system (STS, EMSAM) was introduced with improved side effect profiles and efficacy compared with the conventional form of the selegiline oral tablet. STS allows the targeted inhibition of the monoamine A (MAO-A) and MAO-B isoenzymes with minimal effects on the MAO-A in the gastrointestinal and hepatic systems. Hence, STS can reduce the risk of interactions with tyramine-rich foods. Many fundamental clinical and preclinical studies have reported that 6 mg/24 h of STS is effective against MDD without the need for dietary restrictions with an equal efficacy and improved safety profile. In addition, STS might benefit MDD patients with atypical features or who are resistant to other antidepressants. Overall, familiarity with the properties and indications of STS will have the clinicians another option of biological treatments for MDD patients but subsequent more data including actual post-market clinical experiences will be mandatory.