A double-blind, placebo-controlled outpatient trial of pergolide for cocaine dependence

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.

A randomized placebo-controlled trial of N-acetylcysteine for cannabis use disorder in adults

BACKGROUND

Cannabis use disorder (CUD) is a prevalent and impairing condition, and established psychosocial treatments convey limited efficacy. In light of recent findings supporting the efficacy of N-acetylcysteine (NAC) for CUD in adolescents, the objective of this trial was to evaluate its efficacy in adults.

METHODS

In a 12-week double-blind randomized placebo-controlled trial, treatment-seeking adults ages 18-50 with CUD (N=302), enrolled across six National Drug Abuse Treatment Clinical Trials Network-affiliated clinical sites, were randomized in a 1:1 ratio to a 12-week course of NAC 1200mg (n=153) or placebo (n=149) twice daily. All participants received contingency management (CM) and medical management. The primary efficacy measure was the odds of negative urine cannabinoid tests during treatment, compared between NAC and placebo participants.

RESULTS

There was not statistically significant evidence that the NAC and placebo groups differed in cannabis abstinence (odds ratio=1.00, 95% confidence interval 0.63-1.59, p=0.984). Overall, 22.3% of urine cannabinoid tests in the NAC group were negative, compared with 22.4% in the placebo group. Many participants were medication non-adherent; exploratory analysis within medication-adherent subgroups revealed no significant differential abstinence outcomes by treatment group.

CONCLUSIONS

In contrast with prior findings in adolescents, there is no evidence that NAC 1200mg twice daily plus CM is differentially efficacious for CUD in adults when compared to placebo plus CM. This discrepant finding between adolescents and adults with CUD may have been influenced by differences in development, cannabis use profiles, responses to embedded behavioral treatment, medication adherence, and other factors.

Evaluation of the "Pipeline" for Development of Medications for Cocaine Use Disorder: A Review of Translational Preclinical, Human Laboratory, and Clinical Trial Research

Cocaine use disorder is a persistent public health problem for which no widely effective medications exist. Self-administration procedures, which have shown good predictive validity in estimating the abuse potential of drugs, have been used in rodent, nonhuman primate, and human laboratory studies to screen putative medications. This review assessed the effectiveness of the medications development process regarding pharmacotherapies for cocaine use disorder. The primary objective was to determine whether data from animal and human laboratory self-administration studies predicted the results of clinical trials. In addition, the concordance between laboratory studies in animals and humans was assessed. More than 100 blinded, randomized, fully placebo-controlled studies of putative medications for cocaine use disorder were identified. Of the 64 drugs tested in these trials, only 10 had been examined in both human and well-controlled animal laboratory studies. Within all three stages, few studies had been conducted for each drug and when multiple studies had been conducted conclusions were sometimes contradictory. Overall, however, there was good concordance between animal and human laboratory results when the former assessed chronic drug treatment. Although only seven of the ten reviewed drugs showed fully concordant results across all three types of studies reviewed, the analysis revealed several subject-related, procedural, and environmental factors that differ between the laboratory and clinical trial settings that help explain the disagreement for other drugs. The review closes with several recommendations to enhance translation and communication across stages of the medications development process that will ultimately speed the progress toward effective pharmacotherapeutic strategies for cocaine use disorder.

Molecular changes in the medial prefrontal cortex and nucleus accumbens are associated with blocking the behavioral sensitization to cocaine

Previous studies have demonstrated that cocaine-induced behavioral sensitization is associated with persistent functional and structural alterations in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc); however, the molecular mechanisms underlying these changes have not been elucidated. In this study, the behavioral sensitization to cocaine was established in Sprague Dawley rats and was measured by locomotion and behavioral rating. The brain tissue homogenization was used for measuring the level of brain-derived neurotrophic factor (BDNF), the expression and activity of integrin-linked kinase (ILK), level of protein kinase B (Akt) phosphorylation at serine 473 and threonine 308, and the expression of p75(NTR), TrkA, and TrkB protein. The Results showed that cocaine sensitization was associated with increased BDNF, ILK activity, phospho-Akt Ser(473), p75(NTR), and TrkB protein levels in the mPFC and NAc core. The combination of pergolide and ondansetron normalized not only behavioral sensitization, but also the increases in these molecular markers. Dual immunofluoresence staining showed that ILK expression is co-distributed with p75(NTR) and TrkA expression in both the mPFC and NAc core. Results suggested that the BDNF-TrkA/p75(NTR)-ILK-Akt signaling pathway may be active in cocaine sensitization and associated neural plasticity in the mPFC and NAc core.

Dopamine agonists for the treatment of cocaine dependence

BACKGROUND

Cocaine misuse is a disorder for which no pharmacological treatment of proven efficacy exists. Advances in neurobiology could guide future medication development.

OBJECTIVES

To investigate the efficacy and acceptability of dopamine agonists alone or in combination with any psychosocial intervention for the treatment of of people who misuse cocaine.

SEARCH METHODS

We run the search on 12 January 2015. We searched the Cochrane Drugs and Alcohol Group (CDAG) Specialized Register, PubMed, EMBASE, CINAHL, PsycINFO, ICTRP, clinicaltrials.gov and screened reference lists.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing dopamine agonists alone or associated with psychosocial intervention with placebo, no treatment or other pharmacological interventions.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures.

MAIN RESULTS

Twenty four studies, including 2147 participants, met the inclusion criteria. Comparing any dopamine agonist versus placebo, we found no differences for any of the outcomes considered: dropout (moderate quality of evidence), abstinence (low quality of evidence), severity of dependence (low quality of evidence), adverse events (moderate quality of evidence). This was also observed when single dopamine agonists were compared against placebo. Comparing amantadine versus antidepressants, we found low quality of evidence that antidepressants performed better for abstinence (RR 0.25, 95% CI 0.12 to 0.53) based on two studies with 44 participants. No differences were found for dropout or adverse events, for both moderate quality of evidence.The major flaws of the included studies concerned selection bias because most studies did not report information about sequence generation (80%) and allocation concealment methods (86%): half of the included studies were judged at unclear risk of performance bias and 62.5% at unclear risk of detection bias for what concerns subjective outcomes.

AUTHORS' CONCLUSIONS

Current evidence from RCTs does not support the use of dopamine agonists for treating cocaine misuse. This absence of evidence may leave to clinicians the alternative of balancing the possible benefits against the potential adverse effects of the treatment. Even the potential benefit of combining a dopamine agonist with a more potent psychosocial intervention, which was suggested by the previous Cochrane Review (Soares 2003), is not supported by the results of this Cochrane Review update.

Achieving cannabis cessation -- evaluating N-acetylcysteine treatment (ACCENT): design and implementation of a multi-site, randomized controlled study in the National Institute on Drug Abuse Clinical Trials Network

Despite recent advances in behavioral interventions for cannabis use disorders, effect sizes remain modest, and few individuals achieve long-term abstinence. One strategy to enhance outcomes is the addition of pharmacotherapy to complement behavioral treatment, but to date no efficacious medications targeting cannabis use disorders in adults through large, randomized controlled trials have been identified. The National Institute on Drug Abuse Clinical Trials Network (NIDA CTN) is currently conducting a study to test the efficacy of N-acetylcysteine (NAC) versus placebo (PBO), added to contingency management, for cannabis cessation in adults (ages 18-50). This study was designed to replicate positive findings from a study in cannabis-dependent adolescents that found greater odds of abstinence with NAC compared to PBO. This paper describes the design and implementation of an ongoing 12-week, intent-to-treat, double-blind, randomized, placebo-controlled study with one follow-up visit four weeks post-treatment. Approximately 300 treatment-seeking cannabis-dependent adults will be randomized to NAC or PBO across six study sites in the United States. The primary objective of this 12-week study is to evaluate the efficacy of twice-daily orally-administered NAC (1200 mg) versus matched PBO, added to contingency management, on cannabis abstinence. NAC is among the first medications to demonstrate increased odds of abstinence in a randomized controlled study among cannabis users in any age group. The current study will assess the cannabis cessation efficacy of NAC combined with a behavioral intervention in adults, providing a novel and timely contribution to the evidence base for the treatment of cannabis use disorders.

Atomoxetine does not alter cocaine use in cocaine dependent individuals: double blind randomized trial

BACKGROUND

Cocaine abuse continues to be a significant public health problem associated with morbidity and mortality. To date, no pharmacotherapeutic approach has proven effective for treating cocaine use disorders. Preclinical and clinical evidence suggests that noradrenergic activity may play a role in mediating some effects of cocaine and may be a rational target for treatment.

METHODS

This double blind, placebo-controlled randomized, parallel group, 12-week outpatient clinical trial enrolled cocaine dependent individuals seeking treatment to examine the potential efficacy of the selective norepinephrine reuptake inhibitor, atomoxetine (80 mg/day; p.o.; n = 25), compared to placebo (n = 25). Subjects were initially stratified on cocaine use (< 15 days or ≥ 15 days of the last 30), age and race using urn randomization. Attendance, medication adherence and study compliance were reinforced with contingency management, and weekly counseling was offered. An array of measures (vital signs, laboratory chemistries, cognitive and psychomotor tests, cocaine craving and urine samples for drug testing) was collected throughout the study and at follow-up.

RESULTS

Survival analysis revealed no differences in study retention between the two groups, with approximately 56% of subjects completing the 12-week study (Cox analysis χ(2) = .72; p = .40; Hazard Ratio 1.48 [95% CI 0.62-3.39]). GEE analysis of the proportion of urine samples positive for benzoylecgonine, a cocaine metabolite, revealed no differences between the atomoxetine and placebo groups (χ(2) = 0.2, p = .66; OR = 0.89 [95% CI 0.41-1.74]). Atomoxetine was generally well tolerated in this population.

CONCLUSIONS

These data provide no support for the utility of atomoxetine in the treatment of cocaine dependence.

Pharmacologically-mediated reactivation and reconsolidation blockade of the psychostimulant-abuse circuit: a novel treatment strategy

Psychostimulant abuse continues to present legal, socioeconomic and medical challenges as a primary psychiatric disorder, and represents a significant comorbid factor in major psychiatric and medical illnesses. To date, monotherapeutic drug treatments have not proven effective in promoting long-term abstinence in psychostimulant abusers. In contrast to clinical trials utilizing monotherapies, combinations of dopamine (DA) agonists and selective 5-HT(3), 5HT(2A/2C), or NK(1) antagonists have shown robust efficacy in reversing behavioral and neurobiological alterations in animal models of psychostimulant abuse. One important temporal requirement for these treatments is that the 5-HT or NK(1) receptor antagonist be given at a critical time window after DA agonist administration. This requirement may reflect a necessary dosing regimen towards normalizing underlying dysfunctional neural circuits and "addiction memory" states. Indeed, chronic psychostimulant abuse can be conceptualized as a consolidated form of dysfunctional memory maintained by repeated drug- or cue-induced reactivation of neural circuit and subsequent reconsolidation. According to this concept, the DA agonist given first may reactivate this memory circuit, thereby rendering it transiently labile. The subsequent antagonist is hypothesized to disrupt reconsolidation necessary for restabilization, thus leading progressively to a therapeutically-mediated abolishment of dysfunctional synaptic plasticity. We propose that long-term abstinence in psychostimulant abusers may be achieved not only by targeting putative mechanistic pathways, but also by optimizing drug treatment regimens designed to disrupt the neural processes underlying the addicted state.

Cognitive control and the dopamine D₂-like receptor: a dimensional understanding of addiction

The phenotypic complexity of psychiatric conditions is revealed by the dimensional nature of these disorders, which consist of multiple behavioral, affective, and cognitive dysfunctions that can result in substantial psychosocial impairment. The high degree of heterogeneity in symptomatology and comorbidity suggests that simple categorical diagnoses of "affected" or "unaffected" may fail to capture the true characteristics of the disorder in a manner relevant to individualized treatment. A particular dimension of interest is cognitive control ability because impairments in the capacity to control thoughts, feelings, and actions are key to several psychiatric disorders. Here, we describe evidence suggesting that cognitive control over behavior is a crucial dimension of function relevant to addictions. Moreover, dopamine (DA) D(2)-receptor transmission is increasingly being identified as a point of convergence for these behavioral and cognitive processes. Consequently, we argue that measures of cognitive control and D(2) DA receptor function may be particularly informative markers of individual function and treatment response in addictions.

Dopamine agonists for the treatment of cocaine dependence

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 dopamine agonists alone or in combination with any psychosocial intervention for the treatment of cocaine abuse and dependence

SEARCH METHODS

We searched the Cochrane Drugs and Alcohol Group (CDAG) Specialized Register, PubMed, EMBASE and CINAHL, PsycINFO in June 2011 and researchers for unpublished trials

SELECTION CRITERIA

Randomised and controlled clinical trials comparing dopamine agonists alone or associated with psychosocial intervention with placebo, no treatment, other pharmacological interventions

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data

MAIN RESULTS

Twenty three studies, 2066 participants, met the inclusion criteria. Comparing any dopamine agonist versus placebo, placebo performed better for severity of dependence, four studies, 232 participants, SMD 0.43 (95% CI 0.15 to 0.71), depression, five studies, 322 participants, SMD 0.42 (95% CI 0.19 to 0.65) and abstinent at follow up RR 0.57 (95% CI 0.35 to 0.93). No statistically significant different for the other outcomes considered. Comparing amantadine versus placebo, results never gain the statistical significance, but there is a trend in favour of amantadine for dropouts and depression. Results on adverse events and depression, were in favour of placebo although the difference do not reach the statistical significance. Comparing bromocriptine and Ldopa/Carbidopa versus placebo, results never reached statistical significance. Comparing amantadine versus antidepressants, antidepressants performed better for abstinence. The other two outcomes considered did not show statistically significant differences although dropouts and adverse events tended to be more common in the antidepressant group.The quality of evidence, assessed according to GRADE method, may be judged as moderate for the efficacy of any dopamine agonist versus placebo and as moderate to high for amantadine versus placebo and versus antidepressants.

AUTHORS' CONCLUSIONS

Current evidence from randomised controlled trials does not support the use of dopamine agonists for treating cocaine dependence. This absence of evidence may leave to clinicians the alternative of balancing the possible benefits against the potential adverse effects of the treatment. Even the potential benefit of combining a dopamine agonist with a more potent psychosocial intervention which was suggested by the previous Cochrane review (Soares 2003), is not supported by the results of this updated review.

Reversal of long-term methamphetamine sensitization by combination of pergolide with ondansetron or ketanserin, but not mirtazapine

Psychostimulant abuse represents a psychiatric disorder and societal concern that has been largely unamenable to therapeutic interventions. We have previously demonstrated that the 5-HT₃ antagonist ondansetron or non-selective 5-HT(₂A/₂C) antagonist ketanserin administered 3.5 h following daily pergolide, a non-selective DA agonist, reverses previously established cocaine sensitization. The present study was conducted to evaluate whether the same treatments or delayed pairing of pergolide with the antidepressant mirtazapine can also reverse consolidated methamphetamine (METH) behavioral sensitization. Sprague-Dawley rats received METH infusion via osmotic minipumps (25 mg/kg/day, s.c.) for 7 days, with accompanying daily injections of escalating METH doses (0-6 mg/kg, s.c.). This regimen takes into account the faster elimination of METH in rats, and is designed to replicate plasma METH concentrations with superimposed peak drug levels as observed during METH binging episodes in humans. Following a 7-day METH withdrawal, ondansetron (0.2 mg/kg, s.c.), ketanserin (1.0 mg/kg, s.c.), or mirtazapine (10mg/kg, i.p.) was administered 3.5 h after pergolide injections (0.1 mg/kg, s.c., qd) for 7 days. Behavioral sensitization as a model of METH abuse was assessed 14 days after the combination treatment cessation (i.e., day 28 of METH withdrawal) through an acute challenge with METH (0.5 mg/kg, i.p.). Pergolide combined with ondansetron or ketanserin reversed METH behavioral sensitization, but pergolide-mirtazapine combination was ineffective. The role of reactivation of addiction "circuit" by a non-selective DA agonist, and subsequent reconsolidation blockade through 5-HT₃ or 5-HT₂ antagonism in reversal of METH sensitization and treatment of METH addiction is discussed.

Biological and psychological interventions: trends in substance use disorders intervention research

Substance use disorders (SUDs) cause serious medical, financial, and social problems for individuals and society. Thus, understanding the large body of research exploring biological and psychological intervention trends is important to researchers and clinicians. Historically, psychological interventions have dominated the literature, in spite of modest outcome data. Recently, a refocus on biological intervention research has led to results suggested as efficacious in treatment of SUDs with promising clinical potential. The current review indicates that there seems to be some incongruence between this growing body of physiological research and psychological clinical research and practice. The current review explores these trends and argues for more solid integration of biological and psychological research and treatment strategies for SUDs, as well as heightened efforts toward translation of research into practice.

Intranasal cocaine functions as reinforcer on a progressive ratio schedule in humans

Cocaine dependence continues to be a worldwide public health concern. Although the majority of individuals reporting cocaine use do so via the intranasal route, relatively few laboratory experiments have examined the reinforcing effects of cocaine administered intranasally. The purpose of this experiment was to measure the reinforcing effects of intranasal cocaine using a progressive ratio schedule in which eight cocaine-using subjects chose between doses of cocaine (4 [placebo], 15, 30 and 45 mg) and an alternative reinforcer ($0.25). During each session, subjects first sampled the dose of cocaine available that day and then made six choices between that dose and money, which were available on concurrent progressive ratio schedules of responding. Break points for active cocaine doses were higher than those for placebo but no statistically significant active versus placebo dose effects were observed on subject-rated or physiological measures. These data demonstrate that intranasal cocaine functions as a reinforcer under a progressive ratio schedule in humans. Future research should test higher cocaine doses and larger values of the alternative reinforcer. These procedures may be useful for examining the influence of putative pharmacological and behavioral interventions on intranasal cocaine self-administration.

WITHDRAWN: Dopamine agonists for cocaine dependence

BACKGROUND

Cocaine dependence is a common and serious condition, which has become a substantial public health problem. There is a wide and well documented range of consequences associated to chronic use of cocaine, such as medical, psychological and social problems.. Therapeutic management of the cocaine addicts includes an initial period of abstinence from the drug. During this phase the subjects may experience, besides the intense craving for cocaine, symptoms such as depression, fatigue, irritability, anorexia, and sleep disturbances. It was demonstrated that the acute use of cocaine may enhance dopamine transmission and chronically it decreases dopamine concentrations in the brain. Pharmacological treatment that affects dopamine could theoretically reduce these symptoms and contribute to a more successful therapeutic approach.

OBJECTIVES

To evaluate the efficacy and acceptability of dopamine agonists for treating cocaine dependence.

SEARCH STRATEGY

Electronic searches of Cochrane Library, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; reference searching; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence, was performed for the primary version of this review in 2001. Another search of the electronic databases was done in December of 2002 for this update. The specialised register of trials of the Cochrane Group on Drugs and Alcohol was searched until February 2003.

SELECTION CRITERIA

The inclusion criteria for all randomised controlled trials were that they should focus on the use of dopamine agonists on the treatment of cocaine dependence.

DATA COLLECTION AND ANALYSIS

The reviewers extracted the data independently and Relative Risks, weighted mean difference and number needed to treat were estimated. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity of the final results to this assumption.

MAIN RESULTS

Seventeen studies were included, with 1224 participants randomised. Amantadine, bromocriptine, and pergolide were the drugs evaluated. The main outcomes evaluated were positive urine sample for cocaine metabolites, for efficacy, and retention in treatment, as an acceptability measure. There were no significant differences between interventions, and in trials where participants had primary cocaine dependence or had additional diagnosis of opioid dependence and/or were in methadone maintenance treatment.

AUTHORS' CONCLUSIONS

Current evidence does not support the clinical use of dopamine agonists in the treatment of cocaine dependence. Given the high rate of dropouts in this population, clinicians may consider adding other supportive measures aiming to keep patients in treatment.

Reinforcing effects of stimulants in humans: sensitivity of progressive-ratio schedules

Drug self-administration methodologies have been developed for use in humans to model naturalistic stimulant drug-taking behaviors. These methodologies use a number of schedules of reinforcement, including progressive-ratio schedules. As the name implies, in a progressive-ratio schedule, the response requirement for each subsequent delivery of drug increases, and the primary outcome variable is often the break point (i.e., the last ratio completed to receive a drug delivery). These schedules have been used in a number of human laboratory studies evaluating the reinforcing effects of stimulants. The results of these studies have demonstrated that progressive-ratio schedules are sensitive to manipulation of a pharmacological variable, dose, and to nonpharmacological variables contributing to stimulant drug effects. In addition, findings with progressive-ratio schedules are largely concordant with clinical findings, suggesting that drug self-administration under these schedules has predictive validity in terms of drug abuse and dependence. Future research is necessary, however, to understand better how pharmacological factors like route of administration, onset of effects, and pretreatment influence the reinforcing effects of stimulants under progressive-ratio schedules.

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.

Bupropion hydrochloride versus placebo, in combination with cognitive behavioral therapy, for the treatment of cocaine abuse/dependence

Bupropion hydrochloride is a dopamine and norepinephrine reuptake inhibitor which may be an effective treatment for cocaine dependence due to its ability to reverse deficits in dopaminergic functioning that occur in chronic cocaine users. We performed a randomized, double-blind, placebo controlled trial comparing outpatient treatment with bupropion (N = 37) and placebo (N = 33) in combination with standard cognitive behavioral therapy. There were no statistically significant differences between bupropion and placebo in treatment outcomes, including aggregate measures of urine drug screen results (Joint Probability Index at 16 weeks: 0.43 for bupropion and 0.38 for placebo), treatment retention, cocaine craving ratings, and assessments of depressive symptoms. The failure to find an effect for bupropion relative to placebo, when combined with standard cognitive behavioral therapy, dampens enthusiasm for future development of bupropion as a cocaine pharmacotherapy.

Therapeutic options and challenges for substances of abuse

Addiction to substances continues to be a significant public health concern in the United States. The following review of current pharmacological treatments discusses a range of substances: nicotine, alcohol, cocaine, and opioids. The goal is to provide an overview of currently available and new pharmacological treatments for substance use disorders, while also addressing the pharmacothera-peutic challenges remaining. The significant advances in pharmacotherapy have had limited utilization, however. For example, naltrexone for alcoholism is infrequently prescribed, buprenorphine for opiates still has relatively few qualified prescribers, and stimulants have no Food and Drug Administration-approved pharmacotherapy. These pharmacotherapies are needed, with the rate of even the relatively uncommon abuse of opiates now rising sharply.

Reversal of cocaine sensitization-induced behavioral sensitization normalizes GAD67 and GABAA receptor alpha2 subunit expression, and PKC zeta activity

We have recently shown in rats that cocaine-induced behavioral sensitization can be reversed by a 5-day treatment with ondansetron given 3.5 h after daily pergolide injections. In this study we further investigated the molecular/neurochemical alterations underlying cocaine sensitization and pergolide/ondansetron-mediated reversal. Results revealed that glutamic acid decarboxylase (GAD(65)/GAD(67)) is higher abundant in the nucleus accumbens (NAc) than that in the caudate and medial prefrontal cortex (mPFC), while GABA(A) receptor alpha2 subunit level in the NAc shell is less abundant than that in the NAc core, mPFC and caudate. Cocaine sensitization led to (1) a decrease in GAD(67) expression, an increase in total protein kinase C (PKC) zeta subtype and phosphorylated PKC zeta/lambda levels in the NAc core; (2) a decrease in GAD(67) and GABA(A) receptor alpha2 subunit expression, and an increase in phosphorylated PKC zeta/lambda levels in the NAc shell; (3) an increase in GAD(67) expression in the caudate. Importantly, pergolide/ondansetron treatment reversed these alterations. These results suggest that reversal of cocaine-induced behavioral sensitization is associated with reversal of region-specific changes in GABA function and PKC activity in the striatum.

Reduction in methamphetamine induced sensitization and reinstatement after combined pergolide plus ondansetron treatment during withdrawal

We have previously found the 5-HT3 receptor antagonist ondansetron to be useful in reducing cocaine self-administration and cocaine induced sensitization in rats when given during cocaine withdrawal. More recently we have found the combination of the dopamine agonist pergolide plus ondansetron, 3.5 h later, to reverse cocaine sensitization and associated changes in NMDA and AMPA receptors. Here we tested this drug combination in 1) a methamphetamine sensitization model and 2) a reinstatement model after intravenous methamphetamine self-administration using a nose-poke task. We found pergolide plus ondansetron given from days 3-7 of methamphetamine withdrawal to reverse methamphetamine induced sensitization and attenuate reinstatement. We hypothesize that pergolide may evoke a methamphetamine associated memory and that ondansetron can disrupt its reconsolidation. These data suggest that pergolide plus ondansetron treatment may be useful as a therapy to reduce relapse in methamphetamine abusers.

Reversal of cocaine-induced behavioral sensitization and associated phosphorylation of the NR2B and GluR1 subunits of the NMDA and AMPA receptors

Cocaine abusers remain vulnerable to drug craving and relapse for many years after abstinence is achieved. We have recently shown that ondansetron (a 5-HT3 receptor antagonist) given 3.5 h after each daily cocaine injection reverses previously established behavioral sensitization. The purpose of the present investigation was two-fold. First, as cocaine cannot be used as therapy, we examined whether pergolide (a D1/D2 receptor agonist with reduced abuse potential) and ondansetron could reverse behavioral sensitization. Second, we investigated whether these behavioral changes were associated with parallel alterations in expression levels and/or phosphorylation changes in the NR2B and GluR1 subunits of the respective NMDA and AMPA receptors. Rats were injected for 5 consecutive days with cocaine or saline followed by 9 days of withdrawal. Starting on withdrawal day 10, animals were given vehicle, pergolide/saline, or pergolide/ondansetron for 5 consecutive days. Following a second 9-day period of withdrawal, all animals were challenged with cocaine for assessment of behavioral sensitization and tissues were collected on the following day for Western blot. Sensitization was associated with increased NR2B expression in the accumbens (NAc) shell and decreased Tyr1472 phosphorylation in the NAc core, as well as increased Ser845 phosphorylation of the GluR1 subunit in prefrontal cortex, NAc core, and shell. Pergolide/ondansetron treatment, but not pergolide alone, consistently reversed both the behavioral sensitization and the associated changes in the NMDA and AMPA receptor subunits. To the extent that sensitization plays a role in chronic cocaine abuse, a combination of these clinically available drugs may be useful in treatment of the disorder.

Clinical effects and management of methamphetamine abuse

Methamphetamine is a highly potent and addictive drug that is abused in the United States and around the world. The drug is inexpensive and easily manufactured from simple chemicals such as pseudoephedrine. These features, coupled with its long half-life and highly addictive nature, contribute to the increasing problem of illicit methamphetamine use. Abuse of this agent has both acute and chronic serious health consequences. Policy makers and public health officials must continue to develop programs that educate the public and limit the abuse associated with methamphetamine.

Bromocriptine treatment for cocaine addiction: association with plasma prolactin levels

Bromocriptine is a dopamine receptor agonist used with mixed success in the treatment of cocaine addiction. Variations in dopamine receptor sensitivity may help account for these differences. We evaluated this question in a 24-week outpatient controlled clinical trial in 70 cocaine-abusing (DSM-III) men (86% African-American, mean age 34 years, mean 39 months of regular cocaine use [predominantly smoked]). Subjects received 4 weeks of inpatient treatment. During the last 2 weeks they were inducted onto bromocriptine (maximum dose 2.5mg po tid) (n=35) or placebo (n=35). Plasma prolactin concentrations were assayed before and after the first bromocriptine dose (1.25mg po) as a measure of dopamine receptor sensitivity. After discharge, subjects continued on medication with weekly group counseling. Bromocriptine significantly suppressed prolactin concentrations (4.4 ng/ml decrease), while placebo did not (0.1 ng/ml decrease). Both groups decreased their cocaine use, with no significant group differences in retention in treatment or proportion of cocaine-positive urine samples. There was no significant association between basal plasma prolactin concentrations or prolactin response to first bromocriptine dose and either outcome measure. These data do not support the efficacy of bromocriptine treatment nor a role for prolactin concentration in predicting treatment response.

Nefazodone in out-patient treatment of inhaled cocaine dependence: a randomized double-blind placebo-controlled trial

AIMS

To assess the efficacy of oral nefazodone in the treatment of cocaine dependence.

DESIGN

A 10-week randomized double-blind clinical trial was performed.

METHODS

All 210 subjects fulfilled Diagnostic and Statistical Manual version IV (DSM-IV) criteria for cocaine dependence and were assigned randomly to 300 mg/day of oral nefazodone (N) or placebo (P). Self-reported drug use, retention interval in treatment, adherence to prescription and depressive symptoms were assessed by the Hamilton scale.

FINDINGS

Abstinence from cocaine for 3 weeks or more was achieved by 49.5% (N) and 45.7% (P) (P = 0.58), but 16.2% (N) and 22.9% (P) used other drugs during abstinence. The average interval to resumption of drug use was 33.9 days (N) and 36.1 days (P). Adverse effects were reported by 45.8% (N) and 29.5% (P) (P = 0.01). Treatment for these events was needed more often in N (24.0%) than in P (9.5%) (P < 0.02).

CONCLUSIONS

These results do not support the indication of nefazodone for out-patient treatment of inhaled cocaine dependence with or without other associated drug dependence diagnoses.

Pharmacogenetics and Human Molecular Genetics of Opiate and Cocaine Addictions and Their Treatments

Opiate and cocaine addictions are major social and medical problems that impose a significant burden on society. Despite the size and scope of these problems, there are few effective treatments for these addictions. Methadone maintenance is an effective and most widely used treatment for opiate addiction, allowing normalization of many physiological abnormalities caused by chronic use of short-acting opiates. There are no pharmacological treatments for cocaine addiction. Epidemiological, linkage, and association studies have demonstrated a significant contribution of genetic factors to the addictive diseases. This article reviews the molecular genetics and pharmacogenetics of opiate and cocaine addictions, focusing primarily on genes of the opioid and monoaminergic systems that have been associated with or have evidence for linkage to opiate or cocaine addiction. This evidence has been marshalled either through identification of variant alleles that lead to functional alterations of gene products, altered gene expression, or findings of linkage or association studies. Studies of polymorphisms in the mu opioid receptor gene, which encodes the receptor target of some endogenous opioids, heroin, morphine, and synthetic opioids, have contributed substantially to knowledge of genetic influences on opiate and cocaine addiction. Other genes of the endogenous opioid and monoaminergic systems, particularly genes encoding dopamine beta-hydroxylase, and the dopamine, serotonin, and norepinephrine transporters have also been implicated. Variants in genes encoding proteins involved in metabolism or biotransformation of drugs of abuse and also of treatment agents are reviewed.

DHEAS and POMS measures identify cocaine dependence treatment outcome

Early attrition is a significant problem in the treatment of cocaine dependence, but it is unclear why some patients succeed in treatment while others relapse or drop out of treatment without a demonstrated relapse. The goal of this study was to determine whether baseline levels of select hormones, including the adrenal hormone and excitatory neurosteroid dehydroepiandrosterone sulfate (DHEAS), would distinguish between treatment outcome groups. Based on the literature, completion of 90 days of treatment was established as a key outcome variable.

METHODS

Quantitative urine levels of the cocaine metabolite benzoylecgonine (BE) and other substance of abuse analytes, plasma levels of DHEAS, DHEA, cortisol, and prolactin, and the profile of mood states (POMS) were serially measured in 38 male cocaine-dependent (DSM-IV) patients and in 28 controls of similar gender and age over a six month study. Exclusion criteria for the patients and controls included Axis I mood, anxiety or psychotic disorders. The patients could not manifest substance dependence except to cocaine. The patients and controls received remuneration for urine and blood collection. Blood samples for hormone levels were obtained between 8 and 10 a.m. on days 1, 14 and 21 of a 21-day inpatient treatment program and throughout 6 months of outpatient study visits at 45-day intervals.

RESULTS

Attrition from treatment and study appointments occurred predominately at the junction between inpatient and outpatient programs. Forty percent of patients made the transition to outpatient treatment and remained abstinent and in treatment for a median of 103 days (ABST). Forty-two percent of patients dropped out of treatment during the inpatient stay or never returned after completing the inpatient program (DO) and 18% had a documented relapse either during, or within the first week after, the inpatient stay (REL). POMS total scores were elevated at treatment entry for both the ABST and DO groups. Plasma DHEAS levels in the DO patients were decreased compared to controls and increased in the ABST patients. POMS total scores for the REL patients at baseline were at control levels. Baseline cortisol levels were not statistically different between the outcome groups, though they were elevated for all cocaine patient groups. When treatment outcome was collapsed into whether patients completed (ABST) or did not complete 90 days of treatment (90N), ABST plasma DHEAS and cortisol were significantly elevated compared to the 90N patients and controls across the first 3 weeks of cocaine withdrawal.

CONCLUSIONS

At treatment entry, each of the three patient outcome groups was identified by levels of circulating DHEAS and distressed mood. In the ABST patients, distressed mood during withdrawal may have been mitigated through antidepressant-like actions of enhanced endogenous DHEAS activity, thus contributing to improved abstinence and treatment retention. Patients, such as the DO group, with high levels of distressed mood at treatment entry and low DHEAS levels may benefit from adjunctive pharmacotherapy that targets DHEAS and POMS measures. Patients, such as the REL group, who lack distressed mood at treatment entry, may require intense application of motivational approaches plus residential treatment.

Use of dopamine agonist pergolide in outpatient treatment of cocaine dependence

The dopamine agonist pergolide was evaluated in the treatment of 42 men who manifested cocaine dependence in a single-blind, 4-week-long placebo-controlled study, during 1998-1999 in São Paulo, Brazil. The patients were randomly assigned to two groups: the first group received pergolide (0.05-0.2 mg per day) and the second group received placebo (one to four tablets per day). Urine toxicology screens were obtained. The groups were compared in terms of depressive symptoms, "craving," use of cocaine, side effects of medications, results of urine tests, and retention in treatment. At 3 months' follow-up, the participants were reassessed. No differences were found between the two groups.

Crystal Methamphetamine, Its Analogues, and HIV Infection: Medical and Psychiatric Aspects of a New Epidemic

The use of the recreational drug crystal methamphetamine among younger homosexual men is expanding, and with it, unsafe sex behaviors that increase the transmission of human immunodeficiency virus (HIV). This article reviews available literature on the medical and psychiatric morbidities associated with methamphetamine abuse in HIV-infected patients. Medical complications include hypertension, hyperthermia, rhabdoymyolysis, and stroke. One fatal case of ingestion of methamphetamine with HIV medication has been documented. Two fatal cases of ingestion of HIV medication with the amphetamine analogue n-methyl-3,4 methylenedioxymethamphetamine (MDMA, or "ecstasy") have also been reported. Some molecular researchers suggest that dopaminergic systems are vulnerable to the combined neurotoxicity of HIV infection and methamphetamine. Population surveys indicate high rates of HIV infection among methamphetamine abusers and high rates of unprotected anal intercourse during drug intoxication. Intoxication can sometimes produce paranoia, auditory hallucinations, and, occasionally, violent behavior. Amphetamine withdrawal commonly results in symptoms of depression. Methamphetamine is a new challenge related to treatment and prevention of HIV infection.

Neurobiologic processes in drug reward and addiction

Neurophysiologic processes underlie the uncontrolled, compulsive behaviors defining the addicted state. These"hard-wired"changes in the brain are considered critical for the transition from casual to addictive drug use. This review of preclinical and clinical (primarily neuroimaging) studies will describe how the delineation between pleasure, reward, and addiction has evolved as our understanding of the biologic mechanisms underlying these processes has progressed. Although the mesolimbic dopaminergic efflux associated with drug reward was previously considered the biologic equivalent of pleasure, dopaminergic activation occurs in the presence of unexpected and novel stimuli (either pleasurable or aversive) and appears to determine the motivational state of wanting or expectation. The persistent release of dopamine during chronic drug use progressively recruits limbic brain regions and the prefrontal cortex, embedding drug cues into the amygdala (through glutaminergic mechanisms) and involving the amygdala, anterior cingulate, orbitofrontal cortex, and dorsolateral prefrontal cortex in the obsessive craving for drugs. The abstinent, addicted brain is subsequently primed to return to drug use when triggered by a single use of drug, contextual drug cues, craving, or stress, with each process defined by a relatively distinct brain region or neural pathway. The compulsive drive toward drug use is complemented by deficits in impulse control and decision making, which are also mediated by the orbitofrontal cortex and anterior cingulate. Within this framework, future targets for pharmacologic treatment are suggested.

Dopamine agonists for cocaine dependence

BACKGROUND

Cocaine dependence is a common and serious condition, which has become nowadays a substantial public health problem. There is a wide and well documented range of consequences associated to chronic use of this drug, such as medical, psychological and social problems, including the spread of infectious diseases (e.g. AIDS, hepatitis and tuberculosis), crime, violence and neonatal drug exposure. Therapeutic management of the cocaine addicts includes an initial period of abstinence from the drug. During this phase the subjects may experience, besides the intense craving for cocaine, symptoms such as depression, fatigue, irritability, anorexia, and sleep disturbances. It was demonstrated that the acute use of cocaine may enhance dopamine transmission and chronically it decreases dopamine concentrations in the brain. Pharmacological treatment that affects dopamine could theoretically reduce these symptoms and contribute to a more successful therapeutic approach.

OBJECTIVES

To evaluate the efficacy and acceptability of dopamine agonists for treating cocaine dependence.

SEARCH STRATEGY

Electronic searches of Cochrane Library, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; reference searching; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence, was performed for the primary version of this review in 2001. Another search of the electronic databases was done in December of 2002 for this update. The specialised register of trials of the Cochrane Group on Drugs and Alcohol was searched until February 2003.

SELECTION CRITERIA

The inclusion criteria for all randomised controlled trials were that they should focus on the use of dopamine agonists on the treatment of cocaine dependence.

DATA COLLECTION AND ANALYSIS

The reviewers extracted the data independently and Relative Risks, weighted mean difference and number needed to treat were estimated. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity of the final results to this assumption.

MAIN RESULTS

Seventeen studies were included, with 1224 participants randomised. Amantadine, bromocriptine, and pergolide were the drugs evaluated. The main outcomes evaluated were positive urine sample for cocaine metabolites, for efficacy, and retention in treatment, as an acceptability measure. There were no significant differences between interventions, and in trials where participants had primary cocaine dependence or had additional diagnosis of opioid dependence and/or were in methadone maintenance treatment.

REVIEWER'S CONCLUSIONS

Current evidence does not support the clinical use of dopamine agonists in the treatment of cocaine dependence. Given the high rate of dropouts in this population, clinicians may consider adding other supportive measures aiming to keep patients in treatment.

Pharmacological treatment of cocaine dependence: a systematic review

AIMS

Cocaine dependence is a common and serious condition, associated with severe medical, psychological and social problems, including the spread of infectious diseases. This systematic review assesses critically the efficacy of pharmacotherapy for treating cocaine dependence.

METHODS

The literature search strategy included: electronic searches of Cochrane Library holdings, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; scans of reference lists of relevant articles, personal communications, conference abstracts, unpublished trials from the pharmaceutical industry and book chapters on the treatment of cocaine dependence. Randomized controlled trials (RCTs) focusing on the use of antidepressants (ADs), carbamazepine (CBZ), dopamine agonists (DAs) and other drugs used in the treatment of cocaine dependence were included. The reviewers extracted data independently, and relative risks (RR) with 95% confidence interval (CI) were estimated. Qualitative assessments were carried out using a Cochrane validated checklist. Where possible, analysis was carried out according to 'intention-to-treat' principles.

FINDINGS

The search strategy generated 45 different trials. Most studied drugs were ADs (20 studies), DAs and CBZ. Data were very heterogeneous, with dropout rates within the studies between 0 and 84%. A non-significant trend favoring CBZ was found in terms of dropouts (RR 0.88; 95% CI 0.75-1.03) and results from one trial suggest that fluoxetine patients are less likely to drop out. The main efficacy outcome reported in the studies was the presence of cocaine metabolites in the urine. No significant results were found, regardless the type of drug or dose used for all relevant outcomes assessed.

CONCLUSIONS

There is no current evidence supporting the clinical use of CBZ, antidepressants, dopamine agonists, disulfiram, mazindol, phenytoin, nimodipine, lithium and NeuRecover-SA in the treatment of cocaine dependence. Larger randomized investigation must be considered, while taking into account that these time-consuming efforts should be reserved for medications showing more relevant and promising evidence. Given the high dropout rate among the test population, clinicians may wish to consider adding psychotherapeutic supportive measures aimed at keeping patients in treatment programs.

The potential of dopamine agonists in drug addiction

The use of dopamine agonists in alcohol, stimulant and nicotine dependence has been examined. The direct agonists, such as bromocriptine and pergolide, have not shown utility in alcohol or cocaine abuse and dependence in larger controlled trials. Indirect agents, such as selegiline, may be helpful in cocaine or nicotine abuse and larger clinical trials are underway. Disulfiram may also raise dopamine levels and has shown promise for cocaine dependence. Other indirect agents, such as mazindol and methylphenidate, have not proven effective for cocaine addiction but have not been tested in alcohol or nicotine abuse. Agents for subtypes of dopamine receptors, such as D3, and the use of partial agonists may be useful future treatment approaches. Animal studies also suggest that tailoring treatment to subgroups of patients based on genotype may improve responses.

Utilização do agonista dopaminérgico pergolida no tratamento da "fissura" por cocaína

OBJETIVOS: O estudo avaliou a eficácia e a segurança terapêutica do agonista dopaminérgico pergolida no tratamento ambulatorial da ''fissura" por cocaína. MÉTODOS: Participaram de estudo controlado simples-cego, com duração de quatro semanas, em tratamento ambulatorial, 42 pacientes do sexo masculino com idade entre 18 e 50 anos, com diagnóstico de dependência de cocaína pelo DSM-IV e primeiro grau completo. Transtornos clínicos e/ou psiquiátricos que necessitassem de internação, uso de medicação psiquiátrica, quadros psicóticos prévios independentes do consumo de cocaína e hipersensibilidade à pergolida foram critérios de exclusão. Os pacientes foram divididos aleatoriamente em dois grupos: o primeiro recebeu pergolida (0,05-0,2 mg ao dia), e o segundo, placebo (1 a 4 comprimidos ao dia). Os grupos foram comparados quanto à ''fissura'' por cocaína e aos efeitos colaterais das medicações. RESULTADOS: Não foram encontradas diferenças estatisticamente significativas entre os dois grupos em relação à incidência de efeitos colaterais ou ao relato da redução da ''fissura'' por cocaína. CONCLUSÃO: A amostra pequena e o uso de medicação por tempo curto podem ter influído nos resultados. A pergolida se mostrou segura, com poucos efeitos colaterais. A pergolida não se mostrou superior ao placebo no tratamento da "fissura" por cocaína.

Alcohol and substance abuse

Substance abuse and dependence is a public health problem with far-reaching societal implications. The acute toxicity of substances of abuse and medical consequences of chronic use are substantial. On a more optimistic note, a great deal of progress has been made in understanding and treating substance use disorders. Expanding knowledge concerning the neurobiology of substances of abuse and substance use disorders has led to a growth in pharmacotherapeutic treatment options. A growth in understanding of behavioral processes, motivational issues, and processes of behavioral change has been important in designing new and increasingly more effective psychosocial treatments. A growing body of evidence indicates that the treatment of substance use disorders can be effective, making early diagnosis and treatment or referral increasingly important.