Promising medications for cocaine dependence treatment

Effects of Beta Lactams on Behavioral Outcomes of Substance Use Disorders: A Meta-Analysis of Preclinical Studies

INTRODUCTION

Preclinical studies demonstrated that beta-lactams have neuroprotective effects in conditions involving glutamate neuroexcitotoxicity, including substance use disorders (SUDs). This meta-analysis aims to analyze the existing evidences on the effects of beta-lactams as glutamate transporter 1 (GLT-1) upregulators in animal models of SUDs, identification of gaps in the literature, and setting the stage for potential translation into clinical phases.

METHODS

Meta-analysis was conducted on preclinical studies retrieved systematically from MEDLINE and ScienceDirect databases. Abused substances were identified by refereeing to the National Institute on Drug Abuse (NIDA). The results were quantitatively described with a focus on the behavioral outcomes. Treatment effect sizes were described using standardized mean difference, and they were pooled using random effect model. I2-statistic was used to assess heterogeneity, and Funnel plot and Egger's test were used for assessment of publication bias.

RESULTS

Literature search yielded a total of 71 studies that were eligible to be included in the analysis. Through these studies, the effects of beta-lactams were evaluated in animal models of nicotine, cannabis, amphetamines, synthetic cathinone, opioids, ethanol, and cocaine use disorders as well as steroids-related aggressive behaviors. Meta-analysis showed that treatments with beta-lactams consistently reduced the pooled undesired effects of the abused substances in several paradigms, including drug-self administration, conditioned place preference, drug seeking behaviors, hyperlocomotion, withdrawal syndromes, tolerance to analgesic effects, hyperalgesia, and hyperthermia.

CONCLUSION

This meta-analysis revealed that enhancing GLT-1 expression in the brain through beta-lactams seemed to be a promising treatment approach in the context of substance use disorders, as indicated by results in animal models.

MC-100093, a novel β-lactam GLT-1 enhancer devoid of antimicrobial properties attenuates cocaine relapse in rats

Cocaine use disorder (CUD) currently lacks FDA-approved treatments. In rodents, the glutamate transporter-1 (GLT-1) is downregulated in the nucleus accumbens following cocaine self-administration and increasing the expression and function of GLT-1 reduces the reinstatement of cocaine-seeking. The beta-lactam antibiotic ceftriaxone upregulates GLT-1 and attenuates cue- and cocaine-induced cocaine seeking without affecting motivation for natural rewards. While ceftriaxone shows promise for treating CUD, it possesses characteristics that limit successful translation from bench to bedside, including poor brain penetration, a lack of oral bioavailability and a risk of bacterial resistance when used chronically. Thus, we aimed to develop novel molecules that retained the GLT-1 enhancing effects of ceftriaxone but displayed superior drug-like properties. Here we describe a new monocyclic beta-lactam, MC-100093, as a potent up-regulator of GLT-1 that is orally bioavailable and devoid of antimicrobial properties. MC-100093 was synthesized and tested in vitro and in vivo to determine physiochemical, pharmacokinetic and pharmacodynamic properties. Next, adult male rats underwent cocaine self-administration and extinction training. During extinction training, rats received one of four doses of MC-100093 for 6-8 days prior to a single cue-primed reinstatement test. Separate cohorts of rats were used to assess nucleus accumbens GLT-1 expression and MC-100093 effects on sucrose self-administration. We found that 50 mg/kg MC-100093 attenuated cue-primed reinstatement of cocaine-seeking while upregulating GLT-1 expression in the nucleus accumbens core. This dose did not produce sedation, nor did it decrease sucrose consumption or body weight. Thus, MC-100093 represents a potential treatment to reduce cocaine relapse. Significance Statement Increasing GLT-1 activity reliably reduces drug-seeking across classes of drugs, however, existing GLT1-enhancers have side effects and lack oral bioavailability. To address this issue, novel GLT-1 enhancers were synthesized and the compound with the most favorable pharmacokinetic and pharmacodynamic properties, MC-100093, was selected for further testing. MC-100093 attenuated cued cocaine-seeking without reducing food-seeking or locomotion and upregulated GLT-1 expression in the nucleus accumbens.

Transitioning from interferon-based to direct antiviral treatment options: A potential shift in barriers and facilitators of treatment initiation among people who use drugs?

BACKGROUND

Multiple barriers for accessing hepatitis C virus (HCV) treatment were identified during the interferon-based (IFN) treatment era for people who inject drugs (PWID). Whether these barriers persist since the introduction of IFN-free direct-acting antiviral (DAA) agents in Canada remains to be documented. This study examined temporal trends in HCV treatment initiation and associated factors during the transition from INF-based to all-oral DAA regimens.

METHODS

The study population was drawn from a prospective cohort of PWID in Montreal, Canada. At three-month/one-year intervals between 2011 and 2017, participants with chronic HCV infection completed an interviewer-administered questionnaire on socio-demographic characteristics, drug use and health service utilisation, including HCV treatment. Time-updated Cox multivariate regression models, stratified by DAA + INF (2011-2013) and all-oral DAA (2014-2017) availability periods, were conducted to examine associations between time to HCV treatment initiation and associated barriers and facilitators.

RESULTS

Of 308 participants (85% male, median age 42 [IQR: 33, 50]), 80 (26%) initiated HCV treatment during 915 person-years (PY). Incidence rates increased from 1.6 /100 PY (95%CI:0.9-2.6) in 2011 to 12.7 (10.6-15.1) in 2017 (p-trend = 0.0012). In multivariate analyses, visiting a primary care physician (2011-2013: aHR = 3.63[1.21-10.9]; 2014-2017: 2.52[1.10-5.77]) and frequent injection (0.23[0.05-0.99] and 0.49[0.24-0.99]) were consistently associated with treatment initiation. Participants aged >40 (2.27[1.24-4.13]), receiving opioid agonist therapy (OAT) (2.17[1.19-3.94]), and reporting prior HCV treatment (3.00[1.75-5.15]) were more likely to initiate treatment in the all-oral DAA period.

CONCLUSION

Treatment initiation increased between 2011 and 2017, but still remains low among PWID. Primary care visiting was a key facilitator regardless of the period, while engagement in OAT and health services, indicated by prior HCV treatment, increased the likelihood of treatment initiation in the DAA era. These findings suggest that access to health services is essential but not enough to scale up treatment in this population.

Differential behavioral and molecular alterations upon protracted abstinence from cocaine versus morphine, nicotine, THC and alcohol

Unified theories of addiction are challenged by differing drug-seeking behaviors and neurobiological adaptations across drug classes, particularly for narcotics and psychostimulants. We previously showed that protracted abstinence to opiates leads to despair behavior and social withdrawal in mice, and we identified a transcriptional signature in the extended amygdala that was also present in animals abstinent from nicotine, Δ9-tetrahydrocannabinol (THC) and alcohol. Here we examined whether protracted abstinence to these four drugs would also share common behavioral features, and eventually differ from abstinence to the prototypic psychostimulant cocaine. We found similar reduced social recognition, increased motor stereotypies and increased anxiety with relevant c-fos response alterations in morphine, nicotine, THC and alcohol abstinent mice. Protracted abstinence to cocaine, however, led to strikingly distinct, mostly opposing adaptations at all levels, including behavioral responses, neuronal activation and gene expression. Together, these data further document the existence of common hallmarks for protracted abstinence to opiates, nicotine, THC and alcohol that develop within motivation/emotion brain circuits. In our model, however, these do not apply to cocaine, supporting the notion of unique mechanisms in psychostimulant abuse.

Ondansetron for pediatric concussion; a pilot study for a randomized controlled trial

Objectives

Assess the feasibility of a study evaluating one dose of oral ondansetron to decrease post-concussion symptoms at one week and one month following concussion in children aged 8 to 17 years old.

Method

This was a pilot study for a randomized, triple-blind controlled trial of one dose of either ondansetron or placebo performed in a tertiary care pediatric emergency department. Participants were children aged 8 to 17 years who sustained a concussion in the previous 24 hours and visited a single emergency department. The outcome of interest was an increase from pre-concussion baseline of at least 3 symptoms from the Post-Concussion Symptom Inventory, measured at one week and at one month following concussion. The primary outcome was to determine the proportion of children who completed the assessment at one week following the intervention. Secondary outcome was the proportion of children who completed the assessment at one month following the intervention. All children, care givers, and those assessing the outcomes were blinded to the group assignment.

Results

Of the 218 children presenting with a concussion during the study period, we screened 108 and found 36/108 (33%) eligible to participate and 16/108 (14.8%) agreed to participate. All enrolled patients were compliant with the intervention and follow-up.

Conclusion

In our study population, approximately one-third of the screened concussion patients were eligible to participate and approximately one half of those eligible agreed to participate. Our study found that most enrolled patients preferred electronic follow-up; the noncompliance rate was minimal.

Sex differences in reinstatement of cocaine-seeking with combination treatments of progesterone and atomoxetine

Two repurposed medications have been proposed to treat cocaine abuse. Progesterone, a gonadal hormone, and atomoxetine, a medication commonly used to treat attention deficit/hyperactivity disorder, have both been separately shown to reduce cocaine self-administration and reinstatement (i.e., relapse). The goal of the present study was to examine sex differences in the individual effects of PRO and ATO as well as the combination PRO+ATO treatment on cocaine (COC), caffeine (CAF), and/or cue-primed reinstatement of cocaine-seeking. Adult male and female Wistar rats lever-pressed under a FR 1 schedule for cocaine infusions (0.4mg/kg/inf). After 14 sessions of stable responding in daily 2-h sessions, rats underwent a 21-day extinction period when no drug or drug-related stimuli were present. Rats were then separated into four groups that received PRO (0.5mg/kg) alone (PRO+SAL), ATO (1.5mg/kg) alone (VEH+ATO), control (VEH+SAL) or combination (PRO+ATO) treatments prior to the reinstatement condition. Reinstatement of cocaine-seeking to cues and/or drug injections of cocaine or caffeine was tested after extinction. During maintenance, females self-administered more cocaine than males, but no sex differences were seen during extinction. Females showed greater cocaine-seeking than males after a CAF priming injection. Individual treatment with ATO did not decrease reinstatement under any priming condition; however, the combination treatment decreased cocaine-seeking under the COC+CUES priming condition in males, and both PRO alone and the combination treatment decreased cocaine-seeking in the CAF+CUES condition in females. Overall, PRO alone was only effective in reducing reinstatement in females, while the combination treatment was consistently effective in reducing reinstatement in both sexes.

Sex Differences in Behavioral Dyscontrol: Role in Drug Addiction and Novel Treatments

The purpose of this review is to discuss recent findings related to sex differences in behavioral dyscontrol that lead to drug addiction, and clinical implications for humans are discussed. This review includes research conducted in animals and humans that reveals fundamental aspects of behavioral dyscontrol. The importance of sex differences in aspects of behavioral dyscontrol, such as impulsivity and compulsivity, is discussed as major determinants of drug addiction. Behavioral dyscontrol during adolescence is also an important consideration, as this is the time of onset for drug addiction. These vulnerability factors additively increase drug-abuse vulnerability, and they are integral aspects of addiction that covary and interact with sex differences. Sex differences in treatments for drug addiction are also reviewed in terms of their ability to modify the behavioral dyscontrol that underlies addictive behavior. Customized treatments to reduce behavioral dyscontrol are discussed, such as (1) using natural consequences such as non-drug rewards (e.g., exercise) to maintain abstinence, or using punishment as a consequence for drug use, (2) targeting factors that underlie behavioral dyscontrol, such as impulsivity or anxiety, by repurposing medications to relieve these underlying conditions, and (3) combining two or more novel behavioral or pharmacological treatments to produce additive reductions in drug seeking. Recent published work has indicated that factors contributing to behavioral dyscontrol are an important target for advancing our knowledge on the etiology of drug abuse, intervening with the drug addiction process and developing novel treatments.

Effects of the combination of wheel running and atomoxetine on cue- and cocaine-primed reinstatement in rats selected for high or low impulsivity

BACKGROUND

Aerobic exercise and the attention-deficit/hyperactivity disorder medication, atomoxetine (ATO), are two monotherapies that have been shown to suppress reinstatement of cocaine-seeking in an animal model of relapse. The present study investigated the effects of combining wheel running and ATO versus each treatment alone on cocaine-seeking precipitated by cocaine and cocaine-paired cues in rats with differing susceptibility to drug abuse (i.e., high vs. low impulsive).

METHODS

Rats were screened for high (HiI) or low impulsivity (LoI) based on their performance on a delay-discounting task and then trained to self-administer cocaine (0.4 mg/kg/inf) for 10 days. Following 14 days of extinction, both groups were tested for reinstatement of cocaine-seeking precipitated by cocaine or cocaine-paired cues in the presence of concurrent running wheel access (W), pretreatment with ATO, or both (W+ATO).

RESULTS

HiI rats acquired cocaine self-administration more quickly than LoI rats. While both individual treatments and W+ATO significantly attenuated cue-induced cocaine seeking in HiI and LoI rats, only W+ATO was effective in reducing cocaine-induced reinstatement compared with vehicle treatment. There were dose-dependent and phenotype-specific effects of ATO with HiI rats responsive to the low but not high ATO dose. Floor effects of ATO and W on cue-induced reinstatement prevented the assessment of combined treatment effects.

CONCLUSIONS

These findings demonstrated greater attenuation of cue- versus cocaine-induced reinstatement by ATO and W alone and recapitulate impulsivity phenotype differences in both acquisition of cocaine self-administration and receptivity to treatment.

Effectiveness of secondary prevention and treatment interventions for crack-cocaine abuse: a comprehensive narrative overview of English-language studies

There are an estimated several million crack-cocaine users globally; use is highest in the Americas. Most crack users are socio-economically marginalized (e.g., homeless), and feature elevated risks for morbidity (e.g., blood-borne viruses), mortality and crime/violence involvement, resulting in extensive burdens. No comprehensive reviews of evidence-based prevention and/or treatment interventions specifically for crack use exist. We conducted a comprehensive narrative overview of English-language studies on the efficacy of secondary prevention and treatment interventions for crack (cocaine) abuse/dependence. Literature searches (1990-2014) using pertinent keywords were conducted in main scientific databases. Titles/abstracts were reviewed for relevance, and full studies were included in the review if involving a primary prevention/treatment intervention study comprising a substantive crack user sample. Intervention outcomes considered included drug use, health risks/status (e.g., HIV or sexual risks) and select social outcome indicators. Targeted (e.g., behavioral/community-based) prevention measures show mixed and short-term effects on crack use/HIV risk outcomes. Material (e.g., safer crack use kit distribution) interventions also document modest efficacy in risk reduction; empirical assessments of environmental (e.g., drug consumption facilities) for crack smokers are not available. Diverse psycho-social treatment (including contingency management) interventions for crack abuse/dependence show some positive but also limited/short-term efficacy, yet likely constitute best currently available treatment options. Ancillary treatments show little effects but are understudied. Despite ample studies, pharmaco-therapeutic/immunotherapy treatment agents have not produced convincing evidence; select agents may hold potential combined with personalized approaches and/or psycho-social strategies. No comprehensively effective 'gold-standard' prevention/treatment interventions for crack abuse exist; concerted research towards improved interventions is urgently needed.

A human recombinant monoclonal antibody to cocaine: Preparation, characterization and behavioral studies

Cocaine abuse remains prevalent worldwide and continues to be a major health concern; nonetheless, there is no effective therapy. Immunopharmacotherapy has emerged as a promising treatment strategy by which anti-cocaine antibodies bind to the drug blunting its effects. Previous passive immunization studies using our human monoclonal antibody, GNCgzk, resulted in protection against cocaine overdose and acute toxicity. To further realize the clinical potential of this antibody, a recombinant IgG form of the antibody has been produced in mammalian cells. This antibody displayed a high binding affinity for cocaine (low nanomolar) in line with the superior attributes of the GNCgzk antibody and reduced cocaine-induced ataxia in a cocaine overdose model.

A comprehensive approach to addiction medicine as an appropriate response to the HIV epidemic among drug users

The services for drug-dependence treatment and care, particularly in low-income countries, should not be fragmented and uncoordinated. A basic package of interventions should be provided in the same place and managed by the same team, with a one-stop shop approach. The services for substance use disorders should be appealing, accessible, voluntary-based, and science-based. They should also, like efforts to fight other diseases, be included in the community and the public health systems; that is, those who are affected by drug use and those who serve them should not face discrimination. The first-line assistance and the second-line essential elements of the comprehensive package will be described. The work of the United Nations Office on Drugs and Crime (UNODC) and World Health Organization (WHO) to promote science-based and voluntary-based ethical treatment in Asia will be illustrated.

Assessment of a proposed "three-criteria" cocaine addiction model for use in reinstatement studies with rats

RATIONALE

Relapse is a primary obstacle in the treatment of addiction disorders, and as such, understanding this phenomenon is a major effort of clinical and preclinical studies of cocaine addiction.

OBJECTIVE

A recently developed protocol uses laboratory rats to model cocaine addiction by examining three criteria of addiction-like behaviors (persistent seeking in the absence of drug, high motivation for drug, and resistance to punishment during drug seeking) to detect subjects that possess an addiction phenotype. We closely followed this protocol in order to detect rats possessing this addiction phenotype, with the goal of utilizing this model in future studies investigating potential therapies for relapse in human cocaine addicts.

RESULTS

The majority of the rats used in this study exhibited multiple characteristics thought to be associated with addiction-like behavior in rats, including robust reinstatement to multiple stimuli and high motivation to obtain cocaine. However, no rats displayed the complete addiction phenotype as previously described, due to a complete lack of addiction-like behavior in all subjects on two of the three addiction criteria (drug seeking in the absence of drug and resistance to punishment).

CONCLUSIONS

Our data highlight the independence of behavioral aspects of a rat addiction-like phenotype and suggest that some of these behavioral criteria may be altogether absent in some rat populations. Furthermore, our results suggest a closer review and analysis of some parameters used in this protocol and its global utility.

Efficacy of anti-inflammatory agents to improve symptoms in patients with schizophrenia: an update

BACKGROUND

The inflammatory hypothesis of schizophrenia is not new, but recently it has regained interest because more data suggest a role of the immune system in the pathogenesis of schizophrenia. If increased inflammation of the brain contributes to the symptoms of schizophrenia, reduction of the inflammatory status could improve the clinical picture. Lately, several trials have been conducted investigating the potential of anti-inflammatory agents to improve symptoms of schizophrenia. This study provides an update regarding the efficacy of anti-inflammatory agents on schizophrenic symptoms in clinical studies performed so far.

METHODS

An electronic search was performed using PubMed, Embase, the National Institutes of Health web site http://www.clinicaltrials.gov, Cochrane Schizophrenia Group entries in PsiTri, and the Cochrane Database of Systematic Reviews. Only randomized, double-blind, placebo-controlled studies that investigated clinical outcome were included.

RESULTS

Our search yielded 26 double-blind randomized controlled trials that provided information on the efficacy on symptom severity of the following components: aspirin, celecoxib, davunetide, fatty acids such as eicosapentaenoic acids and docosahexaenoic acids, estrogens, minocycline, and N-acetylcysteine (NAC). Of these components, aspirin (mean weighted effect size [ES]: 0.3, n = 270, 95% CI: 0.06-0.537, I(2) = 0), estrogens (ES: 0.51, n = 262, 95% CI: 0.043-0.972, I(2) = 69%), and NAC (ES: 0.45, n = 140, 95% CI: 0.112-0.779) showed significant effects. Celecoxib, minocycline, davunetide, and fatty acids showed no significant effect.

CONCLUSION

The results of aspirin addition to antipsychotic treatment seem promising, as does the addition of NAC and estrogens. These 3 agents are all very broadly active substances, and it has to be investigated if the beneficial effects on symptom severity are indeed mediated by their anti-inflammatory aspects.

Rhodiola rosea Impairs Acquisition and Expression of Conditioned Place Preference Induced by Cocaine

A novel approach to the treatment of adverse effects of drugs of abuse is one which makes use of natural products. The present study investigated the effect of Rhodiola rosea L. hydroalcoholic extract (RHO) on cocaine-induced hyperactivity and conditioned place preference (CPP) in mice. In a first experiment, mice received RHO (15, 20 or 25 mg/kg, IG), cocaine (25 mg/kg, i.p.) (COC), or a combination of both drugs (COC + RHO15, COC + RHO20, and COC + RHO25), and their locomotor activity was evaluated. In a second experiment, the effects of RHO on the acquisition, expression, and reinstatement of cocaine CPP (induced by drug priming or social defeat stress) were evaluated. RHO alone did not increase activity but potentiated the hyperactivity induced by cocaine. Rhodiola did not induce motivational effects by itself but attenuated the acquisition and expression of cocaine-induced CPP. Moreover, it was found that RHO did not block reinstatement. The results indicate that RHO is effective in reducing the rewarding properties of cocaine but is ineffective in preventing priming or stress-induced cocaine reinstatement. In light of these findings, the benefits of Rhodiola rosea L. as a treatment of cocaine addiction would seem to be limited.

S-(N, N-diethylcarbamoyl)glutathione (carbamathione), a disulfiram metabolite and its effect on nucleus accumbens and prefrontal cortex dopamine, GABA, and glutamate: a microdialysis study

Disulfiram (DSF), used for the treatment of alcohol use disorders (AUDs) for over six decades, most recently has shown promise for treating cocaine dependence. Although DSF's mechanism of action in alcohol abuse is due to the inhibition of liver mitochondrial aldehyde dehydrogenase (ALDH2), its mechanism of action in the treatment of cocaine dependence is unknown. DSF is a pro-drug, forming a number of metabolites each with discrete pharmacological actions. One metabolite formed during DSF bioactivation is S-(N, N-diethylcarbamoyl) glutathione (carbamathione) (carb). We previously showed that carb affects glutamate binding. In the present studies, we employed microdialysis techniques to investigate the effect of carb administration on dopamine (DA), GABA, and glutamate (Glu) in the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC), two brain regions implicated in substance abuse dependence. The effect of DSF on DA, GABA, and Glu in the NAc also was determined. Both studies were carried out in male rats. Carb (20, 50, 200 mg/kg i v) in a dose-dependent manner increased DA, decreased GABA, and had a biphasic effect on Glu, first increasing and then decreasing Glu in both the NAc and mPFC. These changes all occurred concurrently. After carb administration, NAc and mPFC carb, as well as carb in plasma, were rapidly eliminated with a half-life for each approximately 4 min, while the changes in DA, GABA, and GLu in the NAc and mPFC persisted for approximately two hours. The maximal increase in carb (Cmax) in the NAc and mPFC after carb administration was dose-dependent, as was the area under the curve (AUC). DSF (200 mg/kg i p) also increased DA, decreased GABA, and had a biphasic effect on Glu in the NAc similar to that observed in the NAc after carb administration. When the cytochrome P450 inhibitor N-benzylimidazole (NBI) (20 mg/kg i p) was administered before DSF dosing, no carb could be detected in the NAc and plasma and also no changes in NAc DA, GABA, and GLu occurred. Changes in these neurotransmitters occurred only if carb was formed from DSF. When NBI was administered prior to dosing with carb, the increase in DA, decrease in GABA, and biphasic effect on GLu was similar to that seen after dosing with carb only. The i p or i v administration of carb showed similar changes in DA, GABA, and GLu, except the time to reach Cmax for DA as well as the changes in GABA, and GLu after i p administration occurred later. The elimination half-life of carb and the area under the curve (AUC) were similar after both routes of administration. It is concluded that carb must be formed from DSF before any changes in DA, GABA, and GLu in the NAc and mPFC are observed. DSF and carb, when administered to rats, co-release DA, GABA, and GLu. Carb, once formed can cross the blood brain barrier and enter the brain. Although inhibition of liver ALDH2 is the accepted mechanism for DSF's action in treating AUDs, the concurrent changes in DA, GABA, and GLu in the NAc and mPFC after DSF administration suggest that changes in these neurotransmitters as a potential mechanism of action not only for AUDs, but also for cocaine dependence cannot be excluded.

Pregabalin reduces cocaine self-administration and relapse to cocaine seeking in the rat

Pregabalin (Lyrica™) is a structural analog of γ-aminobutyric acid (GABA) and is approved by the FDA for partial epilepsy, neuropathic pain and generalized anxiety disorders. Pregabalin also reduces excitatory neurotransmitter release and post-synaptic excitability. Recently, we demonstrated that pregabalin reduced alcohol intake and prevented relapse to the alcohol seeking elicited by stress or environmental stimuli associated with alcohol availability. Here, we sought to extend these findings by examining the effect of pregabalin on cocaine self-administration (0.25 mg/infusion) and on cocaine seeking elicited by both conditioned stimuli and stress, as generated by administration of yohimbine (1.25 mg/kg). The results showed that oral administration of pregabalin (0, 10 or 30 mg/kg) reduced self-administration of cocaine over an extended period (6 hours), whereas it did not modify self-administration of food. In cocaine reinstatement studies, pregabalin (10 and 30 mg/kg) abolished the cocaine seeking elicited by both the pharmacological stressor yohimbine and the cues predictive of cocaine availability. Overall, these results demonstrate that pregabalin may have potential in the treatment of some aspects of cocaine addiction.

[Cocaine addiction: current data for the clinician]

Cocaine remains the second most commonly used illicit drug worldwide after cannabis. Observed levels of cocaine use among countries considerably vary. An increased cocaine use is recorded in the general European population. Cocaine addiction is a worldwide public health problem, which has somatic, psychiatric, socio-economic and judicial complications. It is a multifactorial disorder variable in its clinical manifestations and heritable. Compared to the general population, there is a high prevalence of somatic and psychiatric disorders among cocaine-dependent patients. There are predictable dose-related effects of pharmacological action of cocaine and effects which are uncommon, unrelated to dose and occur randomly in this population. The number of patients entering drug treatment for primary cocaine use has been increasing in Europe for several years. However, there is no specific pharmacotherapy with established efficacy for the treatment of cocaine addiction, nor is any medication approved by regulatory authorities for such treatment. Recent controlled clinical studies and laboratory studies have highlighted some very promising medications. The perfect therapeutic platform for abstinence initiation and relapse prevention of cocaine addiction is a combination of pharmacological treatments and behavioral treatments. Targeting somatic and psychiatric comorbidity is another way to use pharmacological treatments in addictions.

Hypothalamic neuropeptide S receptor blockade decreases discriminative cue-induced reinstatement of cocaine seeking in the rat

RATIONALE

Previous studies have shown that activation of brain neuropeptide S receptor (NPSR) facilitates reinstatement of cocaine seeking elicited by environmental cues predictive of drug availability. This finding suggests the possibility that blockade of NPSR receptors may be of therapeutic benefit in cocaine addiction. To evaluate this hypothesis, we investigated the effect of two newly synthetized NPSR antagonists, namely the quinolinone-amide derivative NPSR-QA1 and the NPS peptidic analogue [D-Cys(tBu)⁵]NPS on cocaine self-administration and on discriminative cue-induced relapse to cocaine seeking in the rat.

METHODS

Separate groups of rats self-administered food and cocaine 0.25 mg/kg/inf in FR1 and FR5 (fixed ratio reinforcement schedules) for 30-min and 2-h sessions per day. After food and cocaine intake reached baseline levels, the effect of NPSR-QA1 was tested on cocaine and food self-administration. The NPSR-QA1 was injected intraperitoneally and its effect on discriminative cue-induced reinstatement was evaluated, while [D-Cys(tBut)⁵]NPS was injected intracranially, intra-lateral hypothalamus, intra-perifornical area of the hypothalamus, and intra-central amygdala. The effect of the NPSR-QA1 on extinction of cocaine seeking was also assessed.

RESULTS

Intraperitoneal administration of NPSR-QA1 (15-30 mg/kg) did not affect cocaine self-administration. Conversely, NPSR-QA1 (15-30 mg/kg) decreased discriminative cue-induced cocaine relapse. At the lowest dose, this effect was specific, while at the highest dose, NPSR-QA1 also reduced food self-administration. The efficacy of NPSR antagonism on cocaine seeking was confirmed with [D-Cys(tBu)⁵]NPS (10-30 nmol/rat) as it markedly inhibited relapse behavior following site-specific injection into the lateral hypothalamus and the perifornical area of the hypothalamus but not into the central amygdala.

CONCLUSIONS

The identification of the NPS/NPSR system as an important new element involved in the physiopathology of cocaine addiction and the discovery of the anti-addictive properties of NPSR antagonists opens the possibility of exploring a new mechanism for cocaine addiction treatment.

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.

The endogenous opioid system in cocaine addiction: what lessons have opioid peptide and receptor knockout mice taught us?

Cocaine addiction has become a major concern in the UK as Britain tops the European 'league table' for cocaine abuse. Despite its devastating health and socio-economic consequences, no effective pharmacotherapy for treating cocaine addiction is available. Identifying neurochemical changes induced by repeated drug exposure is critical not only for understanding the transition from recreational drug use towards compulsive drug abuse but also for the development of novel targets for the treatment of the disease and especially for relapse prevention. This article focuses on the effects of chronic cocaine exposure and withdrawal on each of the endogenous opioid peptides and receptors in rodent models. In addition, we review the studies that utilized opioid peptide or receptor knockout mice in order to identify and/or clarify the role of different components of the opioid system in cocaine-addictive behaviours and in cocaine-induced alterations of brain neurochemistry. The review of these studies indicates a region-specific activation of the µ-opioid receptor system following chronic cocaine exposure, which may contribute towards the rewarding effect of the drug and possibly towards cocaine craving during withdrawal followed by relapse. Cocaine also causes a region-specific activation of the κ-opioid receptor/dynorphin system, which may antagonize the rewarding effect of the drug, and at the same time, contribute to the stress-inducing properties of the drug and the triggering of relapse. These conclusions have important implications for the development of effective pharmacotherapy for the treatment of cocaine addiction and the prevention of relapse.

Cocaine use reduction with buprenorphine (CURB): rationale, design, and methodology

BACKGROUND

Effective medications to treat cocaine dependence have not been identified. Recent pharmacotherapy trials demonstrate the potential efficacy of buprenorphine (BUP) (alone or with naltrexone) for reducing cocaine use. The National Institute on Drug Abuse Clinical Trials Network (CTN) launched the Cocaine Use Reduction with Buprenorphine (CURB) investigation to examine the safety and efficacy of sublingual BUP (as Suboxone®) in the presence of extended-release injectable naltrexone (XR-NTX, as Vivitrol®) for the treatment of cocaine dependence. This paper describes the design and rationale for this study.

METHODS

This multi-site, double-blind, placebo-controlled study will randomize 300 participants across 11 sites. Participants must meet the DSM-IV criteria for cocaine dependence and past or current opioid dependence or abuse. Participants are inducted onto XR-NTX after self-reporting at least 7 days of abstinence from opioids and tolerating a naloxone challenge followed by oral naltrexone and are then randomly assigned to one of three medication conditions (4 mg BUP, 16 mg BUP, or placebo) for 8 weeks. Participants receive a second injection of XR-NTX 4 weeks after the initial injection, and follow-up visits are scheduled at 1 and 3 months post-treatment. Participants receive weekly cognitive behavioral therapy (CBT). Recruitment commenced in September, 2011. Enrollment, active medication, and follow-up phases are ongoing, and recruitment is exceeding targeted enrollment rates.

CONCLUSIONS

This research using 2 medications will demonstrate whether BUP, administered in the presence of XR-NTX, reduces cocaine use in adults with cocaine dependence and opioid use disorders and will demonstrate if XR-NTX prevents development of physiologic dependence on BUP.

Structural violence in the context of drug policy and initiatives aiming to reduce drug-related harm in contemporary Brazil: a review

Brazil, the 6th largest world economy, has experienced rapid economic, demographic, and social structural changes during the last decade. Notwithstanding, Brazil being one of the most unequal societies worldwide, 40 million of 200 million Brazilians have moved from poverty to middle-class standards during this period. This review analyzes the success of different Brazilian initiatives aiming to reduce drug consumption-related harms, as well as the failed attempts to curb structural violence, despite some very recent initiatives have yet to be fully implemented and evaluated.

Advancing addiction treatment: what can we learn from animal studies?

Substance addiction is a maladaptive behavior characterized by compulsive and uncontrolled self-administration of a substance (drug). Years of research indicate that addictive behavior is the result of complex interactions between the drug, the user, and the environment in which the drug is used; therefore, addiction cannot simply be attributed to the neurobiological actions of a drug. However, despite the obvious complexity of addictive behavior, animal models have both advanced understanding of addiction and contributed importantly to the development of medications to treat this disease. We briefly review recent animal models used to study drug addiction and the contribution of data generated by these animal models for the clinical treatment of addictive disorders.