Pharmacological mechanisms of naltrexone and acamprosate in the prevention of relapse in alcohol dependence

A Review of the Characteristics of Clinical Trials and Potential Medications for Alcohol Dependence: Data Analysis from ClinicalTrials.gov

Objective. This study provides a comprehensive analysis of the characteristics of clinical trials related to alcohol dependence that are registered on ClinicalTrials.gov. Methods. All ClinicalTrials.gov trials registered up to 1 January 2023 were examined, focusing on trials that involved alcohol dependence. All 1295 trials were summarized by presenting their characteristics and results and reviewed most intervention drugs used in the treatment of alcohol dependence. Results. The study analysis identified a total of 1295 clinical trials registered on ClinicalTrials.gov that were focused on alcohol dependence. Of these, 766 trials had been completed, representing 59.15% of the total, while 230 trials were currently recruiting participants, accounting for 17.76% of the total. None of the trials had yet been approved for marketing. The majority of the studies included in this analysis were interventional studies (1145 trials, or 88.41%), which accounted for most of the patients enrolled in the trials. In contrast, observational studies represented only a small portion of the trials (150 studies, or 11.58%) and involved a smaller number of patients. In terms of geographic distribution, the majority of registered studies were located in North America (876 studies, or 67.64%), while only a small number of studies were registered in South America (7 studies, or 0.54%). Conclusions. The purpose of this review is to provide a basis for the treatment of alcohol dependence and prevention of its onset through an overview of clinical trials registered at ClinicalTrials.gov. It also offers essential information for future research to guide future studies.

Exploring the Role of DARPP-32 in Addiction: A Review of the Current Limitations of Addiction Treatment Pathways and the Role of DARPP-32 to Improve Them

We are amidst a global addiction crisis, yet stigmas surrounding addiction counterintuitively prevail. Understanding and appreciating the neurobiology of addiction is essential to dissolve this stigma and for the development of new pharmacological agents to improve upon currently narrow therapeutic options. This review highlights this and evaluates dopamine-and-cAMP-regulated phosphoprotein, Mr 32 kDa (DARPP-32) as a potential target to treat various forms of substance abuse. Despite the proven involvement of DARPP-32 in addiction pathophysiology, no robust investigations into compounds that could pharmacologically modulate it have been carried out. Agents capable of altering DARPP-32 signalling in this way could prevent or reverse drug abuse and improve upon currently substandard treatment options.

Viral Suppression Levels in Men Who Have Sex With Men and Transgender Women With Newly Diagnosed HIV and Alcohol Use Disorder in Peru: Results From a Randomized, Double-Blind, Placebo-Controlled Trial Using Oral Naltrexone

BACKGROUND

Alcohol use disorders (AUDs) are common in men who have sex with men (MSM) and transgender women (TGW) in Peru and undermine antiretroviral therapy (ART) adherence. Oral naltrexone (NTX) is an evidence-based treatment for AUD that has not been assessed in cotreating AUD in MSM/TGW with HIV.

SETTING AND DESIGN

A multi-site, randomized, double-blind, placebo-controlled trial among MSM/TGW with AUD and newly diagnosed with HIV in Lima, Peru.

METHODS

Newly diagnosed MSM/TGW with HIV and AUD were prescribed a single-treatment regimen of EFV/TDF/FTC from 2014 to 2015 and randomized 2:1 to oral NTX (N = 103) or placebo (N = 53) for 24 weeks. The primary and secondary outcomes were proportion achieving viral suppression (VS: HIV-1 RNA < 400 copies/mL) or maximal viral suppression (MVS: HIV-1 RNA < 40 copies/mL) at 24 weeks.

RESULTS

There were no significant differences between the arms in VS (81.6% NTX arm vs 75.5% placebo arm; P = 0.37) or MVS (61.2% NTX arm vs 66.0% placebo arm; P = 0.48). Adherence to study medication was low (mean = 34.6%) overall with only 21.4% of participants meeting recommended adherence levels (≥80% daily doses/month). Participants allocated to NTX had significantly lower adherence compared with placebo for both the first and second 12-week study periods, respectively (44.0% vs 35.2%, P = 0.04; 31.4% vs 35.2%, P = 0.03).

CONCLUSIONS

Findings are inconclusive regarding the use of NTX for treatment of AUD in MSM/TGW newly diagnosed with HIV. VS and MVS levels were high irrespective of allocation. Adherence to study medication was low, requiring further exploration of strategies to optimize adherence to NTX as AUD treatment.

The opioid antagonist naltrexone decreases seizure-like activity in genetic and chemically induced epilepsy models

OBJECTIVE

A significant number of epileptic patients fail to respond to available anticonvulsive medications. To find new anticonvulsive medications, we evaluated FDA-approved drugs not known to be anticonvulsants. Using zebrafish larvae as an initial model system, we found that the opioid antagonist naltrexone exhibited an anticonvulsant effect. We validated this effect in three other epilepsy models and present naltrexone as a promising anticonvulsive candidate.

METHODS

Candidate anticonvulsant drugs, determined by our prior transcriptomics analysis of hippocampal tissue, were evaluated in a larval zebrafish model of human Dravet syndrome (scn1Lab mutants), in wild-type zebrafish larvae treated with the pro-convulsant drug pentylenetetrazole (PTZ), in wild-type C57bl/6J acute brain slices exposed to PTZ, and in wild-type mice treated with PTZ in vivo. Abnormal locomotion was determined behaviorally in zebrafish and mice and by field potential in neocortex layer IV/V and CA1 stratum pyramidale in the hippocampus.

RESULTS

The opioid antagonist naltrexone decreased abnormal locomotion in the larval zebrafish model of human Dravet syndrome (scn1Lab mutants) and wild-type larvae treated with the pro-convulsant drug PTZ. Naltrexone also decreased seizure-like events in acute brain slices of wild-type mice, and the duration and number of seizures in adult mice injected with PTZ.

SIGNIFICANCE

Our data reveal that naltrexone has anticonvulsive properties and is a candidate drug for seizure treatment.

Targeting the Opioid Receptors: A Promising Therapeutic Avenue for Treatment in “Heavy Drinking Smokers”

Aims

Despite a general decline in tobacco use in the last decades, the prevalence of tobacco smoking in individuals with alcohol use disorder (AUD) remains substantial (45–50%). Importantly, the co-use of both substances potentiates the adverse effects, making it a significant public health problem. Substantial evidence suggests that AUD and Tobacco use disorder (TUD) may share common mechanisms. Targeting these mechanisms may therefore provide more effective therapy. Numerous studies describe a potential role of the endogenous opioid system in both AUD and TUD. Reviewing this literature, we aim to evaluate the efficacy of molecules that target the opioid system as promising therapeutic interventions for treating alcohol and tobacco co-use disorders.

Methods

We provide a synthesis of the current epidemiological knowledge of alcohol and tobacco co-use disorders. We evaluate clinical and preclinical research that focuses on the regulation of the endogenous opioid system in alcohol, nicotine, and their interactions.

Results

The epidemiological data confirm that smoking stimulates heavy drinking and facilitates alcohol craving. Pharmacological findings suggest that treatments that are efficacious in the dual addiction provide a beneficial treatment outcome in comorbid AUD and TUD. In this regard, MOP, DOP and NOP-receptor antagonists show promising results, while the findings prompt caution when considering KOP-receptor antagonists as a treatment option in alcohol and tobacco co-use disorders.

Conclusions

Existing literature suggests a role of the opioid system in sustaining the high comorbidity rates of AUD and TUD. Molecules targeting opioid receptors may therefore represent promising therapeutic interventions in ‘heavy drinking smokers.’

Pharmacotherapeutic management of co-morbid alcohol and opioid use

Opioid use disorder (OUD) and alcohol use disorder (AUD) are two highly prevalent substance-related disorders worldwide. Co-use of the substances is also quite prevalent, yet there are no pharmacological treatment approaches specifically designed to treat co-morbid OUD and AUD. Here, the authors critically summarize OUD, AUD and opioid/alcohol co-use and their current pharmacotherapies for treatment. They also review the mechanisms of action of opioids and alcohol within the brain reward circuitry and discuss potential combined mechanisms of action and resulting neuroadaptations. Pharmacotherapies that aim to treat AUD or OUD that may be beneficial in the treatment of co-use are also highlighted. Preclinical models assessing alcohol and opioid co-use remain sparse. Lasting neuroadaptations in brain reward circuits caused by co-use of alcohol and opioids remains largely understudied. In order to fully understand the neurobiological underpinnings of alcohol and opioid co-use and develop efficacious pharmacotherapies, the preclinical field must expand its current experimental paradigms of 'single drug' use to encompass polysubstance use. Such studies will provide insights on the neural alterations induced by opioid and alcohol co-use, and may help develop novel pharmacotherapies for individuals with co-occurring alcohol and opioid use disorders.

The Kappa Opioid Receptor Is Associated With Naltrexone-Induced Reduction of Drinking and Craving

BACKGROUND

Naltrexone is a nonselective opioid receptor antagonist used as a treatment for alcohol use disorder. However, only modest clinical effects have been observed, possibly because of limited knowledge about the biological variables affecting the efficacy of naltrexone. We investigated the potential role of the kappa opioid receptor (KOR) in the therapeutic effect of naltrexone.

METHODS

A total of 48 non-treatment-seeking heavy drinkers (16 women) who met DSM-IV criteria for alcohol dependence participated in two alcohol drinking paradigms (ADPs) separated by a week of open-label naltrexone (100 mg daily). Craving, assessed with the Alcohol Urge Questionnaire and the Yale Craving Scale, and drinking behavior were recorded in each ADP. Prior to naltrexone initiation, KOR availability was determined in the amygdala, hippocampus, pallidum, striatum, cingulate cortex, and prefrontal cortex using positron emission tomography with [¹¹C]LY2795050.

RESULTS

Participants reported lower levels of craving (Yale Craving Scale: -11 ± 1, p < .0001; Alcohol Urge Questionnaire: -6 ± 0.6, p < .0001) and consumed fewer drinks (-3.7 ± 4, p < .0001) during the second ADP following naltrexone therapy. The observed reduction in drinking was negatively associated with baseline KOR availability in the striatum (p = .005), pallidum (p = .023), and cingulate cortex (p = .018). Voxelwise analysis identified clusters in the bilateral insula, prefrontal, and cingulate cortex associated with the reduction in drinking (p < .0001). In addition, KOR availability in all evaluated brain regions was associated with craving measured in both ADPs.

CONCLUSIONS

The KOR is implicated in drinking and craving following naltrexone therapy in alcohol use disorder.

Naltrexone and alcohol effects on craving for cigarettes in heavy drinking smokers

Naltrexone has been extensively studied for the treatment of alcohol use disorder. However, less is known about the effects of naltrexone on smoking outcomes in the context of alcohol use among East Asian individuals who have been suggested to differ in response to alcohol and to naltrexone. The present study is a secondary analysis that used a double-blind placebo-controlled design (n = 31) to examine the (a) effects of alcohol on basal craving for cigarettes, (b) effects of naltrexone on cigarette craving and alcohol craving during alcohol administration, and (c) relationship between craving for alcohol and cigarettes. Heavy drinking smokers of East Asian descent completed two counterbalanced intravenous alcohol administration sessions, one after taking naltrexone (50 mg) for five days and one after taking a placebo for five days. Self-reported subjective craving for cigarettes and for alcohol was recorded during each experimental session. Craving for cigarettes and alcohol increased significantly throughout the intravenous alcohol administration. A significant breath alcohol concentration (BrAC) × Medication interaction revealed that naltrexone blunted cigarette craving during alcohol administration, compared to placebo. Naltrexone significantly reduced craving for alcohol during alcohol administration in this group of heavy drinking smokers. Alcohol craving significantly predicted cigarette craving, however this effect did not vary across rising alcohol administration or by medication. These findings demonstrate that naltrexone reduces the urge to smoke and to drink during alcohol administration. Clinical studies are needed to further ascertain whether naltrexone may be of benefit to this distinct subgroup of heavy drinking smokers. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Efficacy of Pharmacological Interventions in Targeting Decision-Making Impairments across Substance and Behavioral Addictions

Decision-making impairments reflect tendencies towards risky or unwise choices as manifested by presence of psychiatric symptoms or cognitive impairment (e.g. representation of value, inhibitory control-response selection, learning). Such impairments are suggested by the hallmark symptoms of substance and behavioral addictions, which include escalation over time (of substance intake or a given behavior), lack of control, neglect of other domains of life, and cognitive distortions (such as ‘chasing losses’ in gambling disorder). Amongst the putative behavioral addictions, most epidemiological data exist for gambling disorder, which is now included in DSM-5 as a substance-related and addictive disorder. However, other disorders share parallels and may also constitute behavioral addictions, such as compulsive stealing (kleptomania), compulsive shopping, and compulsive sexual behavior. The current paper presents a narrative review of evidence for cognitive decision-making impairments in addictions, as well as pharmacological treatments of these disorders that may have relevance for improving decision-making. We find that objective decision-making deficits have been widely reported in patients with substance use disorders and gambling disorder, compared to controls. Decision-making in the other behavioral addictions is under-studied. Evidence-based pharmacological treatments for some of these addictive disorders, for example, opioid antagonists and glutamatergic agents, modulate neural systems playing key roles in decision-making. But clinical trials have seldom examined effects of such treatments on objective decision-making measures. Future research directions are discussed, including the need to include standardized outcome measures of decision-making (tasks and imaging) alongside traditional clinical measures, to better understand and enhance underlying treatment mechanisms.

Ethanol and Naltrexone Have Distinct Effects on the Lateral Nano-organization of Mu and Kappa Opioid Receptors in the Plasma Membrane

The complex spatiotemporal organization of proteins and lipids in the plasma membrane is an important determinant of receptor function. Certain substances, such as ethanol, can penetrate into the hydrophobic regions of the plasma membrane. By altering protein-lipid and protein-protein interactions, these substances can modify the dynamic lateral organization and the function of plasma membrane receptors. To assess changes in plasma membrane receptor organization, we used photoactivated localization microscopy (PALM). This single molecule localization microscopy technique was employed to quantitatively characterize the effects of pharmacologically relevant concentrations of ethanol and naltrexone (an opioid receptor antagonist and medication used to treat alcohol use disorders) on the lateral nano-organization of mu and kappa opioid receptors (MOR and KOR, respectively). Ethanol affected the lateral organization of MOR and KOR similarly: It reduced the size and occupancy of opioid receptor nanodomains and increased the fraction of opioid receptors residing outside of nanodomains. In contrast, naltrexone affected MOR and KOR lateral organization differently. It significantly increased KOR surface density, nanodomain size, and the occupancy of KOR nanodomains. However, naltrexone marginally affected these parameters for MOR. Pretreatment with naltrexone largely protected against ethanol-induced changes in MOR and KOR lateral organization. Based on these data, we propose a putative mechanism of naltrexone action that operates in addition to its canonical antagonistic effect on MOR- and KOR-mediated signaling.

Self-administration of the synthetic cathinone MDPV enhances reward function via a nicotinic receptor dependent mechanism

Methylenedioxypyrovalerone (MDPV) is an addictive synthetic drug with severe side effects. Previous studies have shown that MDPV has positive reinforcing properties. However, little is known about the effect of MDPV self-administration on the state of the brain reward system and the neuronal mechanisms by which MDPV mediates its effects. The goal of the present studies was to determine the effect of MDPV self-administration on reward function and the role of cholinergic neurotransmission in the reinforcing effects of MDPV. To study the effect of MDPV self-administration on the brain reward system, rats were prepared with intravenous catheters and intracranial self-stimulation electrodes (ICSS). For 10 days, the reward thresholds were assessed immediately before (23 h post prior session) and after 1 h of MDPV self-administration. The reward thresholds were decreased immediately after MDPV self-administration, which is indicative of a potentiation of brain reward function. The reward thresholds 23 h after MDPV intake gradually increased over time, which is indicative of anhedonia. Pretreatment with the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine decreased the self-administration of MDPV and completely prevented the decrease in reward thresholds. A control study with palatable chocolate pellets showed that responding for a natural reinforcer does not affect the state of the brain reward system. Furthermore, mecamylamine did not affect responding for food pellets. In conclusion, the self-administration of MDPV potentiates reward function and nAChR blockade prevents the reward enhancing effects of MDPV self-administration. Preventing the MDPV-induced increase in cholinergic neurotransmission might be a safe approach to diminish MDPV abuse.

High Drinking in the Dark (HDID) mice are sensitive to the effects of some clinically relevant drugs to reduce binge-like drinking

BACKGROUND

There is a serious public health need for better understanding of alcohol use disorder disease mechanisms and for improved treatments. At this writing, only three drugs are approved by the Food and Drug Administration as medications to treat alcohol use disorders - disulfiram, naltrexone, and acamprosate. Binge drinking is a form of abusive alcohol drinking defined by the NIAAA as a drinking to blood alcohol levels (BALs)>0.08% during a period of approximately 2h. To model genetic risk for binge-like drinking, we have used selective breeding to create a unique animal model, High Drinking in the Dark (HDID) mice. Behavioral characterization of HDID mice has revealed that HDID mice exhibit behavioral impairment after drinking, withdrawal after a single binge-drinking session, and escalate their intake in response to induction of successive cycles of dependence. Notably, HDID mice do not exhibit altered tastant preference or alcohol clearance rates. We therefore asked whether drugs of known clinical relevance could modulate binge-like ethanol drinking in HDID mice, reasoning that this characterization of HDID responses should inform future use of this genetic animal model for screening and development of novel potential therapeutics.

METHODS

We tested the efficacy of acamprosate and naltrexone to reduce binge-like drinking in HDID mice. Additionally, we tested the GABAB receptor agonist, baclofen, based on recent pre-clinical and clinical studies demonstrating that it reduces alcohol drinking. We elected not to include disulfiram due to its more limited clinical usage. Mice were tested after acute doses of drugs in the limited-access Drinking in the Dark (DID) paradigm.

RESULTS

HDID mice were sensitive to the effects of acamprosate and baclofen, but not naltrexone. Both drugs reduced binge-like drinking. However, naltrexone failed to reduce drinking in HDID mice. Thus, HDID mice may represent a useful model for screening novel compounds.

A Comparison of Sexual Side Effects of Antidepressants With and Without Naltrexone

OBJECTIVE

The aim of the study was to compare the rate of sexual side effects of the selective serotonin reuptake inhibitor paroxetine versus the tricyclic antidepressant desipramine and to examine the effect of co-prescription of naltrexone on sexual side effects among participants in a randomized clinical trial.

METHODS

This was a secondary analysis (N = 88) of veterans who participated in a 12-week trial. All veterans were randomized into one of four treatment groups: (a) desipramine/naltrexone, (b) desipramine/placebo, (c) paroxetine/naltrexone, and (d) paroxetine/placebo. The main outcome measure was the frequency of sexual side effects consisting of "decreased sex drive" and/or "impotence" reported by veterans at each weekly visit.

RESULTS

Approximately 61% of the veterans reported sexual side effects at least once during the trial, and 26.4% reported sexual side effects throughout the study. There were no significant differences in the frequency of sexual side effects among the four treatment groups. The results were similar when the comparison was made between the two antidepressant groups. There were no significant differences in the reporting of sexual side effects between those receiving desipramine and paroxetine. Also, the comparison between naltrexone and placebo did not alter the results.

CONCLUSIONS

This is the first study to compare frequency of sexual side effect reporting between paroxetine and desipramine. We found no statistically significant differences in sexual side effect reporting between the two antidepressants. Also, the addition of naltrexone did not show any beneficial effect on the sexual side effect profile.

Extended-release naltrexone reduces alcohol consumption among released prisoners with HIV disease as they transition to the community

BACKGROUND

Alcohol use disorders (AUDs) are highly prevalent among persons living with HIV (PLH) within the criminal justice system (CJS). Extended-release naltrexone (XR-NTX) has not been previously evaluated among CJS-involved PLH with AUDs.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted among 100 HIV+ prisoners with AUDs. Participants were randomized 2:1 to receive 6 monthly injections of XR-NTX or placebo starting one week prior to release. Using multiple imputation strategies for data missing completely at random, data were analyzed for the 6-month post-incarceration period. Main outcomes included: time to first heavy drinking day; number of standardized drinks/drinking day; percent of heavy drinking days; pre- to post-incarceration change in average drinks/day; total number of drinking days; and a composite alcohol improvement score comprised of all 5 parameters.

RESULTS

There was no statistically significant difference overall between treatment arms for time-to-heavy-drinking day. However, participants aged 20-29 years who received XR-NTX had a longer time to first heavy drinking day compared to the placebo group (24.1 vs. 9.5days; p<0.001). There were no statistically significant differences between groups for other individual drinking outcomes. A sub-analysis, however, found participants who received ≥4 XR-NTX were more likely (p<0.005) to have improved composite alcohol scores than the placebo group. Post-hoc power analysis revealed that despite the study being powered for HIV outcomes, sufficient power (0.94) was available to distinguish the observed differences.

CONCLUSIONS

Among CJS-involved PLH with AUDs transitioning to the community, XR-NTX lengthens the time to heavy drinking day for younger persons; reduces alcohol consumption when using a composite alcohol consumption score; and is not associated with any serious adverse events.

Alcohol-related cognitive impairment: current trends and future perspectives

Excessive alcohol use is associated with a wide range of physical, psychological and social consequences, and is responsible for a significant proportion of the burden of disease globally. An area which has received increasing interest is alcohol-related brain damage, not just because of the cost to the individual and society through resource utilization, but also because of the potential for prevention and reversibility. This paper aims to review the current literature on this subject and seeks to explore issues around diagnosis and treatment of alcohol-related brain damage.

Treatment-refractory substance use disorder: Focus on alcohol, opioids, and cocaine

Substance use disorders are common, but only a small minority of patients receive adequate treatment. Although psychosocial therapies are effective, relapse is common. This review focusses on novel pharmacological and other treatments for patients with alcohol, opioid, or cocaine use disorders who do not respond to conventional treatments. Disulfiram, acamprosate, and the opioid antagonist naltrexone have been approved for the treatment of alcoholism. A novel, "as needed" approach is the use of the mu-opioid antagonist and partial kappa agonist nalmefene to reduce alcohol consumption. Other novel pharmacological approaches include the GABA-B receptor agonist baclofen, anticonvulsants such as topiramate and gabapentin, the partial nicotine receptor agonist varenicline, and other drugs. For opioid dependence, opioid agonist therapy with methadone or buprenorphine is the first-line treatment option. Other options include oral or depot naltrexone, morphine sulfate, depot or implant formulations, and heroin (diacetylmorphine) in treatment-refractory patients. To date, no pharmacological treatment has been approved for cocaine addiction; however, 3 potential pharmacological treatments are being studied, disulfiram, methylphenidate, and modafinil. Pharmacogenetic approaches may help to optimize treatment response in otherwise treatment-refractory patients and to identify which patients are more likely to respond to treatment, and neuromodulation techniques such as repeated transcranial magnetic stimulation and deep brain stimulation also may play a role in the treatment of substance use disorders. Although no magic bullet is in sight for treatment-refractory patients, some novel medications and brain stimulation techniques have the potential to enrich treatment options at least for some patients.

Number of Drinks to "Feel a Buzz" by HIV Status and Viral Load in Men

The impact of HIV and its treatment on the effects of alcohol remain unclear. Blood alcohol concentrations have been noted to be higher in HIV infected individuals prior to antiretroviral initiation. Our goal was to compare number of drinks to "feel a buzz or high" among HIV infected and uninfected men, stratified by viral load (VL) suppression. Data includes 1478 HIV infected and 1170 uninfected men in the veterans aging cohort study who endorsed current drinking. Mean (SD) number of drinks to feel a buzz was 3.1 (1.7) overall. In multivariable analyses, HIV infected men reported a lower mean number of drinks to feel a buzz compared to uninfected men (coef = -14 for VL < 500; -34 for VL ≥ 500; p ≤ .05). Men with HIV, especially those with a detectable VL, reported fewer drinks to feel a buzz. Future research on the relationship between alcohol and HIV should consider the role of VL suppression.

Nalmefene for the treatment of alcohol use disorders: recent data and clinical potential

INTRODUCTION

Few pharmacotherapies are available for alcoholism. Numerous studies indicate the involvement of the opioid-endorphin system in mediating the reinforcing effects of alcohol via dopaminergic neurons. The opioid antagonist naltrexone was found to be effective in alcohol treatment, and the European Medicines Agency has now approved the mu-opioid antagonist und partial kappa agonist nalmefene.

AREAS COVERED

This article presents background information on the chemistry of nalmefene and pre-clinical and clinical findings. The three relevant Phase III studies, all of which followed a harm-reduction, "as needed" approach and found reduced alcohol consumption with nalmefene 18 (20) mg, are discussed in detail.

EXPERT OPINION

The integration of the "as needed" approach into conventional psychosocial alcohol therapies may be challenging but offers the opportunity to reach otherwise not treated patients. Nalmefene is the first medication to be approved specifically in this indication and seems to be most suitable for patients with alcohol misuse or a rather low physical dependence on alcohol who do not require immediate detoxification or inpatient treatment. Although a categorical distinction between patients who want to stop heavy drinking or drinking at all over time may be somewhat hypothetical, nalmefene offers new treatment options to patients with alcohol use disorder.

Neural substrates of cue reactivity: association with treatment outcomes and relapse

Given the strong evidence for neurological alterations at the basis of drug dependence, functional magnetic resonance imaging (fMRI) represents an important tool in the clinical neuroscience of addiction. fMRI cue-reactivity paradigms represent an ideal platform to probe the involvement of neurobiological pathways subserving the reward/motivation system in addiction and potentially offer a translational mechanism by which interventions and behavioral predictions can be tested. Thus, this review summarizes the research that has applied fMRI cue-reactivity paradigms to the study of adult substance use disorder treatment responses. Studies utilizing fMRI cue-reactivity paradigms for the prediction of relapse and as a means to investigate psychosocial and pharmacological treatment effects on cue-elicited brain activation are presented within four primary categories of substances: alcohol, nicotine, cocaine and opioids. Lastly, suggestions for how to leverage fMRI technology to advance addiction science and treatment development are provided.

The frequency of agitation due to inappropriate use of naltrexone in addicts

Background:

There is a high tendency among specialists to treat the addicts with naltrexone; withdrawal symptoms are frequent after taking naltrexone along with opioids. This study investigated the frequency of agitation due to inappropriate use of naltrexone in addicts.

Materials and Methods:

This was a cross-sectional study, conducted in Noor and Aliasghar hospitals in Isfahan city. The study population included the addicts who were agitated as a result of naltrexone abuse. Scores of patients with agitation were measured with Richmond Agitation Sedation Scale (RASS). Patient outcomes including recovery without complications, recovery with complications (rhabdomyolysis), and mortality were recorded.

Results:

All the patients with agitation caused by naltrexone abuse during 1 year were 40 people, of whom nine were excluded due to their comorbid diseases (diabetes or cardiovascular disease). Among the remaining 31 patients, 30 were male. The patients’ mean age was 29.93 (5.24) years. The most common symptoms observed besides agitation was midriasis (41.9%), and vomiting (41.9%), A 38.8% of the patients scored 3 or 4, and, 61.2% scored 1 or 2 for agitation. The mean time for patients’ restlessness scores to reach zero was 9.30 (3.71) h (min: 3 h, max: 18 h). All the patients in both groups were discharged with recovery without complication.

Conclusion:

Considering the high prevalence of agitation in the poisoning emergency department due to inappropriate use of naltrexone, more accurate planning for administration of naltrexone in addicts seems necessary.

Pharmacotherapy of Co-Occurring Schizophrenia and Substance Use Disorders

Substance use disorders, common in patients with schizophrenia, can lead to poor outcomes. Here we review the literature on the use of antipsychotics in patients with co-occurring schizophrenia and substance use disorder as well as evidence for the use of adjunctive pharmacological treatments targeting substance use in these patients. We also discuss a neurobiological formulation suggesting that the cooccurrence of these disorders may be related to a dysfunction in the dopamine mediated brain reward circuitry. Typical antipsychotics do not appear to decrease substance use in this population. Randomized, controlled trials provide some support for use of the atypical antipsychotic clozapine for co-occurring cannabis use disorder, naltrexone and disulfiram for alcohol use disorder, and also nicotine replacement therapy, sustained-release bupropion and varenicline for tobacco use disorder. Nonetheless, data regarding treatment in patients with these co-occurring disorders are still limited, and many studies reported to date have been either underpowered or did not include a control condition. Further research is needed to evaluate optimal pharmacotherapeutic strategies for this population.

Opposing neural effects of naltrexone on food reward and aversion: implications for the treatment of obesity

RATIONALE

Opioid antagonism reduces the consumption of palatable foods in humans but the neural substrates implicated in these effects are less well understood.

OBJECTIVES

The aim of the present study was to examine the effects of the opioid antagonist, naltrexone, on neural response to rewarding and aversive sight and taste stimuli.

METHODS

We used functional magnetic resonance imaging (fMRI) to examine the neural responses to the sight and taste of pleasant (chocolate) and aversive (mouldy strawberry) stimuli in 20 healthy volunteers who received a single oral dose of naltrexone (50 mg) and placebo in a double-blind, repeated-measures cross-over, design.

RESULTS

Relative to placebo, naltrexone decreased reward activation to chocolate in the dorsal anterior cingulate cortex and caudate, and increased aversive-related activation to unpleasant strawberry in the amygdala and anterior insula.

CONCLUSIONS

These findings suggest that modulation of key brain areas involved in reward processing, cognitive control and habit formation such as the dorsal anterior cingulate cortex (dACC) and caudate might underlie reduction in food intake with opioid antagonism. Furthermore we show for the first time that naltrexone can increase activations related to aversive food stimuli. These results support further investigation of opioid treatments in obesity.

Nalmefene for the treatment of alcohol dependence: a current update

To date, few pharmacotherapies have been established for the treatment of alcoholism. There is a plethora of research concerning the involvement of the opioid-endorphin system in mediating the reinforcing effects of alcohol. The opioid antagonist naltrexone has been found to be effective in alcohol treatment. In addition, the mu-opioid antagonist and partial kappa agonist nalmefene was recently approved by the European Medicines Agency for the treatment of alcoholism. The relevant studies followed a harm-reduction, 'as needed' approach and showed a reduction in alcohol consumption with nalmefene 20 mg rather than increased abstinence rates, (which was not the primary goal of the relevant studies). The available literature is reviewed and discussed. Nalmefene appears to be a safe and effective treatment for alcohol dependence.

Modeling longitudinal drinking data in clinical trials: an application to the COMBINE study

BACKGROUND

There is a lack of consensus in the literature as to how to define drinking outcomes in clinical trials. Typically, separate statistical models are fit to assess treatment effects on several summary drinking measures. These summary measures do not capture the complexity of drinking behavior. We used the COMBINE study to illustrate a statistical approach for examining treatment effects on high-resolution drinking data.

METHODS

This is a secondary data analysis of COMBINE participants randomly assigned to naltrexone, acamprosate, with medical management and/or combined behavioral intervention (CBI). Using a Poisson hurdle model, abstinence and number of drinks were simultaneously modeled as a function of treatment and covariates. An emphasis was placed on the evaluation of "risky drinking" (3 drinks/day for women and 4 for men).

RESULTS

During treatment, naltrexone increased the odds of abstinence vs placebo naltrexone (OR=1.35 [1.06, 1.65]) but receiving CBI in addition to naltrexone (vs not) obscured this effect; thus, the naltrexone effect was largest in the group not receiving CBI (OR=1.87 [1.29, 2.46]). Naltrexone vs placebo naltrexone also reduced the risk of drinking in those who resumed risky drinking (RR=0.58 [0.24, 0.93]) and increased the odds of maintaining low risk drinking (OT=1.99 [1.07, 2.90]). Both effects were strongest in the absence of CBI when only "medical management" was provided.

CONCLUSIONS

The hurdle model is an appropriate statistical tool for assessing the effect of treatment on the two part drinking process, abstinence and number of drinks. When applied to COMBINE, results bolster the use of naltrexone in promoting abstinence and reduction in risky drinking.

Acamprosate in alcohol dependence: implications of a unique mechanism of action

Acamprosate, in combination with psychosocial therapy, has been shown to be clinically effective in maintaining abstinence in alcohol dependence. Current research suggests that its mechanism of action involves functional antagonism of the ionotropic glutamate N-methyl-d-aspartate (NMDA) receptor. However, direct interactions between acamprosate and the NMDA receptor are weak, and recent findings suggest that acamprosate may modulate NMDA receptors via regulatory polyamine sites, or that it may act directly on metabotropic glutamate receptors. All of these mechanisms are novel for the treatment of alcohol dependence and have far-reaching implications for understanding relapse, as well as for the discovery of drugs with greater efficacy. Understanding the mechanism of action of acamprosate may be an important stimulus for change in the perception and treatment of alcohol dependence.

Safety and efficacy of acamprosate for the treatment of alcohol dependence

Acamprosate (calcium acetylhomotaurine) is an amino acid modulator that has displayed efficacy in some clinical trials in reducing craving and promoting abstinence in alcohol dependent patients following detoxification. While acamprosate is safe and generally well-tolerated, not all studies have demonstrated clinical efficacy that is superior to placebo. In addition, the precise neurochemical mechanisms of action of acamprosate have still not yet been identified. In this review, we summarize current clinical data on the safety, efficacy, and pharmacokinetic properties of acamprosate, as well theories on its potential mechanism of action. We also discuss tolerability and patient preference issues and conclude with a discussion of the place of acamprosate in addiction medicine and therapy.

Current progress in pharmacologic treatment strategies for alcohol dependence

Alcoholism is a progressive neurological disorder that represents one of the leading preventable causes of morbidity and mortality in the USA. Individuals with alcohol dependence may exhibit differences in their sensitivity to intoxication, the age at which they begin heavy drinking or the presentation of comorbid psychiatric illness. The heterogeneous nature of the disorder has complicated efforts to predict treatment outcomes, indicating a need for improved diagnostic and therapeutic approaches. Pharmaceutical development has focused on treating the symptoms of alcohol withdrawal, reducing consumption of and craving for alcohol, preventing relapse and treating associated psychiatric problems. Current therapies may be optimized by combining psychosocial and pharmacologic approaches to treat alcoholic patients with the most appropriate regimen to achieve the desired therapeutic outcome. This article will describe the neurobiological mechanisms of dependence on alcohol in brief and review major medications approved for the treatment of alcoholism with regard to recent clinical evidence for the therapeutic efficacy of each agent. Investigations on the use of drugs with other indications (e.g., antidepressants and anticonvulsants) to target alcohol-dependent subtypes will also be discussed.

Acamprosate: safety and tolerability in the treatment of alcohol dependence

Acamprosate, in conjunction with psychosocial treatment, has demonstrated efficacy in maintaining abstinence in alcohol-dependent patients in multiple clinical trials. Data from 13 short-term (≤26 weeks) and long-term (≥48 weeks) clinical trials were analyzed to assess the safety and tolerability of acamprosate: 4234 patients were randomized to placebo (N = 1962), acamprosate 1332 mg/d (N = 440), 1998 mg/d (N = 1749), or 3000 mg/d (N = 83). Overall incidence of treatment-emergent adverse events (AEs) was 61% for acamprosate and 56% for placebo (P < 0.01). The majority of AEs in all groups were reported as transient and considered "mild" or "moderate" in severity, and discontinuation rates due to AEs were comparable. Most common AEs were diarrhea (16% acamprosate versus 10% placebo, P < 0.01) and flatulence (3% acamprosate versus 2% placebo, P < 0.01). Patients taking concomitant medications commonly used to treat alcohol dependence reported comparable AEs between placebo- and acamprosate-treated groups.Acamprosate was shown to be safe in patients with hepatic impairment. A dose reduction is recommended in patients with renal impairment. No clinically meaningful between-group differences were reported for clinical chemistry tests or vital sign parameters. This ad hoc analysis demonstrates that acamprosate can be used safely in alcohol-dependent patients, including those taking concomitant medications, or having renal or hepatic impairment.

Delta and kappa opioid receptor polymorphisms influence the effects of naltrexone on subjective responses to alcohol

Naltrexone, one of four FDA-approved pharmacotherapies for alcohol dependence, has shown moderate efficacy in clinical trials. Pharmacogenetic effects have been reported such that allelic variation at the gene encoding the mu-opioid receptor (OPRM1, rs1799971) predicts naltrexone-induced blunting of the positively reinforcing effects of alcohol. However, naltrexone also binds, albeit to a lesser degree, to kappa and delta opioid receptors in the brain. This alternate binding presents the possibility that single nucleotide polymorphisms (SNPs) in the kappa and delta opioid receptor (OPRK1 and OPRD1) genes may contribute to naltrexone pharmacogenetics. Therefore, the goal of this exploratory study was to re-examine data from a double-blind placebo controlled laboratory trial of naltrexone for pharmacogenetic effects at kappa and delta opioid receptor tag SNPs. Participants were 40 heavy drinkers (12 female) who underwent an intravenous alcohol challenge paradigm after receiving naltrexone (50mg) or placebo in randomized and crossover fashion. Dependent variables were self-reported alcohol-induced stimulation, sedation, and craving. Multilevel models revealed a significant Naltrexone×OPRK1 Genotype (rs997917) interaction predicting alcohol-induced sedation, such that TT homozygotes reported lower naltrexone-induced alcohol sedation as compared to carriers of the C allele. Moreover, there was a significant Naltrexone×OPRD1 Genotype (rs4654327) interaction predicting alcohol-induced stimulation and craving, such that carriers of the A allele at this locus reported greater naltrexone-induced blunting of alcohol stimulation and alcohol craving compared to GG homozygotes. These findings suggest that additional pharmacogenetic effects in the opioid receptor system may account for individual differences in response to naltrexone in the human laboratory.

Design and synthesis of a bivalent ligand to explore the putative heterodimerization of the mu opioid receptor and the chemokine receptor CCR5

The bivalent ligand approach has been utilized not only to study the underlying mechanism of G protein-coupled receptors dimerization and/or oligomerization, but also to enhance ligand affinity and/or selectivity for potential treatment of a variety of diseases by targeting this process. Substance abuse and addiction have made both the prevention and the treatment of human immunodeficiency virus (HIV) infection more difficult to tackle. Morphine, a mu opioid receptor (MOR) agonist, can accelerate HIV infection through up-regulating the expression of the chemokine receptor CCR5, a well-known co-receptor for HIV invasion to the host cells and this has been extensively studied. Meanwhile, two research groups have described the putative MOR-CCR5 heterodimers in their independent studies. The purpose of this paper is to report the design and synthesis of a bivalent ligand to explore the biological and pharmacological process of the putative MOR-CCR5 dimerization phenomenon. The developed bivalent ligand thus contains two distinct pharmacophores linked through a spacer; ideally one of which will interact with the MOR and the other with the CCR5. Naltrexone and Maraviroc were selected as the pharmacophores to generate such a bivalent probe. The overall reaction route to prepare this bivalent ligand was convergent and efficient, and involved sixteen steps with moderate to good yields. The preliminary biological characterization showed that the bivalent compound 1 retained the pharmacological characteristics of both pharmacophores towards the MOR and the CCR5 respectively with relatively lower binding affinity, which tentatively validated our original molecular design.

Pharmacogenetics of naltrexone in asian americans: a randomized placebo-controlled laboratory study

Recent clinical and laboratory studies have shown that the effects of naltrexone for alcoholism may be moderated by the Asn40Asp single-nucleotide polymorphism (SNP) of the μ-opioid receptor gene (OPRM1). Allele frequencies for this polymorphism, however, have been shown to vary substantially as a function of ethnic background, such that individuals of Asian descent are more likely to carry the minor (Asp40) allele. The objective of this study is to test the naltrexone pharmacogenetic effects of the Asn40Asp SNP in a sample of Asian Americans. This study consists of a double-blinded, randomized, placebo-controlled laboratory trial of naltrexone. Participants (n=35, 10 females; 13 Asn40Asn and 22 Asp40 carriers) were non-treatment-seeking heavy drinkers recruited from the community. After taking naltrexone or placebo, participants completed an intravenous alcohol administration session. The primary outcome measures were subjective intoxication and alcohol craving. Results suggested that Asp40 carriers experienced greater alcohol-induced sedation, subjective intoxication, and lower alcohol craving on naltrexone, as compared to placebo, and to Asn40 homozygotes. There results were maintained when controlling for ALDH2 (rs671) and ADH1B (rs1229984) markers and when examining the three levels of OPRM1 genotype, thereby supporting an OPRM1 gene dose response. These findings provide a much-needed extension of previous studies of naltrexone pharmacogenetics to individuals of Asian descent, an ethnic group more likely to express the minor allele putatively associated with improved biobehavioral and clinical response to this medication. These findings help further delineate the biobehavioral mechanisms of naltrexone and its pharmacogenetics.

Critical thoughts on current rodent models for evaluating potential treatments of alcohol addiction and withdrawal

Despite years of neurobiological research that have helped to identify potential therapeutic targets, we do not have a reliable pharmacological treatment for alcoholism. There are a range of possible explanations for this failure, including arguments that alcoholism is a spectrum disorder and that different population subtypes may respond to different treatments. This view is supported by categorisations such as early- and late-onset alcoholism, whilst multifactorial genetic factors may also alter responsivity to pharmacological agents. Furthermore, experience of alcohol withdrawal may play a role in future drinking in a way that may distinguish alcoholism from other forms of addiction. Additionally, our neurobiological models, based largely upon results from rodent studies, may not mimic specific aspects of the human condition and may reflect different underlying phenomena and biological processes from the clinical pattern. As a result, potential treatments may be targeting inappropriate aspects of alcohol-related behaviours. Instead, we suggest a more profitable approach is (a) to identify well-defined intermediate behavioural phenotypes in human experimental models that reflect defined aspects of the human clinical disorder and (b) to develop animal models that are homologous with those phenotypes in terms of psychological processes and underlying neurobiological mechanisms. This review describes an array of animal models currently used in the addiction field and what they tell us about alcoholism. We will then examine how established pharmacological agents have been developed using only a limited number of these models, before describing some alternative novel approaches to achieving homology between animal and human experimental measures.

Structure selectivity relationship studies of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)carboxamido]morphinan derivatives toward the development of the mu opioid receptor antagonists

Mu opioid receptor antagonists have been applied to target a variety of diseases clinically. The current study is designed to explore the structure selectivity relationship (SSR) of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)carboxamido]morphinan (NAP), a lead compound identified as a selective mu opioid receptor antagonist based on the previous study. Among a series of NAP derivatives synthesized, compounds 6 (NMP) and 9 (NGP) maintained comparable binding affinity, selectivity and efficacy to the lead compound. Particularly, the mu opioid receptor selectivity over kappa opioid receptor of NGP was considerably enhanced compared to that of NAP. Overall, the preliminary SSR supported our original hypothesis that an alternate 'address' domain may exist in the mu opioid receptor, which favors the ligands carrying a hydrogen bond acceptor and an aromatic system to selectively recognize the mu opioid receptor.

Pharmacologically induced alcohol craving in treatment seeking alcoholics correlates with alcoholism severity, but is insensitive to acamprosate

Modulation of alcohol craving induced by challenge stimuli may predict the efficacy of new pharmacotherapies for alcoholism. We evaluated two pharmacological challenges, the α(2)-adrenergic antagonist yohimbine, which reinstates alcohol seeking in rats, and the serotonergic compound meta-chlorophenylpiperazine (mCPP), previously reported to increase alcohol craving in alcoholics. To assess the predictive validity of this approach, the approved alcoholism medication acamprosate was evaluated for its ability to modulate challenge-induced cravings. A total of 35 treatment seeking alcohol dependent inpatients in early abstinence were randomized to placebo or acamprosate (2997 mg daily). Following two weeks of medication, subjects underwent three challenge sessions with yohimbine, mCPP or saline infusion under double blind conditions, carried out in counterbalanced order, and separated by at least 5 days. Ratings of cravings and anxiety, as well as biochemical measures were obtained. In all, 25 subjects completed all three sessions and were included in the analysis. Cravings were modestly, but significantly higher following both yohimbine and mCPP challenge compared with saline infusion. The mCPP, but not yohimbine significantly increased anxiety ratings. Both challenges produced robust ACTH, cortisol and prolactin responses. There was a significant correlation between craving and the degree of alcoholism severity. Acamprosate administration did not influence craving. Both yohimbine and mCPP challenges lead to elevated alcohol craving in a clinical population of alcoholics, and these cravings correlate with alcoholism severity. Under the experimental conditions used, alcohol cravings induced by these two stimuli are not sensitive to acamprosate at clinically used doses.

Assessment of GABA-B, metabotropic glutamate, and opioid receptor involvement in an animal model of binge drinking

Drinking to intoxication or binge drinking is a hallmark characteristic of alcohol abuse. Although hard to model in rodents, the scheduled high alcohol consumption (SHAC) procedure generates high, stable ethanol intake and blood ethanol concentrations in mice to levels consistent with definitions of binge drinking. The purpose of the present studies was to determine the effects of pharmacological manipulation of the opioidergic, glutamatergic, and γ-aminobutyric acid (GABA)ergic systems on binge drinking with the SHAC procedure. Parallel manipulations were conducted in mice trained in operant self-administration of either sucrose or ethanol. For the SHAC procedure, genetically heterogeneous Withdrawal Seizure Control mice were given varying periods of fluid access, with a 30-min ethanol session every third day (total of seven). Mice were pretreated intraperitoneally with naltrexone (0, 0.6, or 1.25 mg/kg), baclofen (0, 2.5, or 5.0 mg/kg), or 2-methyl-6-(phenylethynyl)-pyridine (MPEP; 0, 3.0, or 10.0 mg/kg) before each ethanol session. For the operant self-administration procedure, separate groups of C57BL/6 mice were trained to complete a single response requirement (16 presses on the active lever) to gain 30 min of access to an ethanol or a sucrose solution. Mice received pretreatments of the same doses of naltrexone, MPEP, or baclofen before the self-administration sessions, with saline injections on intervening days. Naltrexone produced a dose-dependent decrease in binge drinking, and the highest dose also significantly decreased operant self-administration of ethanol and sucrose. Both doses of baclofen significantly decreased binge alcohol consumption, but the higher dose also tended to decrease water intake. The highest dose of baclofen also significantly decreased operant self-administration of sucrose. MPEP (10 mg/kg) significantly decreased binge alcohol consumption and sucrose self-administration. These results indicate that manipulation of the opioidergic, glutamatergic, and GABAergic systems significantly decreased binge drinking.

Nalmefene for treatment of alcohol dependence

IMPORTANCE OF THE FIELD

Alcohol use and dependence are frequent disorders. Despite numerous established psychosocial approaches, relapse to heavy drinking is common in alcohol-dependent patients after detoxification and relapse prevention remains a significant medical challenge.

AREAS COVERED IN THIS REVIEW

The opioidergic system plays a crucial role in mediating the rewarding effects of alcohol, in part by modulating dopaminergic neurotransmission in mesolimbic brain areas. This review will discuss the neurochemical basis of alcoholism with respect to the opiodergic system. Nalmefene is an alternate opioid receptor that also targets the kappa opioid receptors and thus offers a different treatment approach. The treatment studies conducted so far are discussed.

WHAT THE READER WILL GAIN

We present a comprehensive overview of the implication of the opioidergic system in mediating the rewarding effects of alcoholism and the preclinical and clinical studies conducted so far with nalmefene.

TAKE HOME MESSAGE

Although the number of clinical studies conducted with naltrexone by far exceeds the number conducted with nalmefene, the four studies on nalmefene published so far may indicate a role of this opioid antagonist in the treatment of alcoholism. Results of some ongoing studies on nalmefene will provide additional data on its use for this indication.

Acamprosate for alcohol dependence

BACKGROUND

Alcohol dependence is among the main leading health risk factors in most developed and developing countries. Therapeutic success of psychosocial programs for relapse prevention is moderate, but could potentially be increased by an adjuvant treatment with the glutamate antagonist acamprosate.

OBJECTIVES

To determine the effectiveness and tolerability of acamprosate in comparison to placebo and other pharmacological agents.

SEARCH STRATEGY

We searched the Cochrane Drugs and Alcohol Group (CDAG) Specialized Register, PubMed, EMBASE and CINAHL in January 2009 and inquired manufacturers and researchers for unpublished trials.

SELECTION CRITERIA

All double-blind randomised controlled trials (RCTs) which compare the effects of acamprosate with placebo or active control on drinking-related outcomes.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. Trial quality was assessed by one author and cross-checked by a second author. Individual patient data (IPD) meta-analyses were used to verify the primary effectiveness outcomes.

MAIN RESULTS

24 RCTs with 6915 participants fulfilled the criteria of inclusion and were included in the review. Compared to placebo, acamprosate was shown to significantly reduce the risk of any drinking RR 0.86 (95% CI 0.81 to 0.91); NNT 9.09 (95% CI 6.66 to 14.28) and to significantly increase the cumulative abstinence duration MD 10.94 (95% CI 5.08 to 16.81), while secondary outcomes (gamma-glutamyltransferase, heavy drinking) did not reach statistical significance. Diarrhea was the only side effect that was more frequently reported under acamprosate than placebo RD 0.11 (95% 0.09 to 0.13); NNTB 9.09 (95% CI 7.69 to 11.11). Effects of industry-sponsored trials RR 0.88 (95% 0.80 to 0.97) did not significantly differ from those of non-profit funded trials RR 0.88 (95% CI 0.81 to 0.96). In addition, the linear regression test did not indicate a significant risk of publication bias (p = 0.861).

AUTHORS' CONCLUSIONS

Acamprosate appears to be an effective and safe treatment strategy for supporting continuous abstinence after detoxification in alcohol dependent patients. Even though the sizes of treatment effects appear to be rather moderate in their magnitude, they should be valued against the background of the relapsing nature of alcoholism and the limited therapeutic options currently available for its treatment.

Nicotine: alcohol reward interactions

It is well established that the continued intake of drugs of abuse is reinforcing-that is repeated consumption increases preference. This has been shown in some studies to extend to other drugs of abuse; use of one increases preference for another. In particular, the present review deals with the interaction of nicotine and alcohol as it has been shown that smoking is a risk factor for alcoholism and alcohol use is a risk factor to become a smoker. The review discusses changes in the brain caused by chronic nicotine and chronic alcohol intake to approach the possible mechanisms by which one drug increases the preference for another. Chronic nicotine administration was shown to affect nicotine receptors in the brain, affecting not only receptor levels and distribution, but also receptor subunit composition, thus affecting affinity to nicotine. Other receptor systems are also affected among others catecholamine, glutamate, GABA levels and opiate and cannabinoid receptors. In addition to receptor systems and transmitters, there are endocrine, metabolic and neuropeptide changes as well induced by nicotine. Similarly chronic alcohol intake results in changes in the brain, in multiple receptors, transmitters and peptides as discussed in this overview and also illustrated in the tables. The changes are sex and age-dependent-some changes in males are different from those in females and in general adolescents are more sensitive to drug effects than adults. Although nicotine and alcohol interact-not all the changes induced by the combined intake of both are additive-some are opposing. These opposing effects include those on locomotion, acetylcholine metabolism, nicotine binding, opiate peptides, glutamate transporters and endocannabinoid content among others. The two compounds lower the negative withdrawal symptoms of each other which may contribute to the increase in preference, but the mechanism by which preference increases-most likely consists of multiple components that are not clear at the present time. As the details of induced changes of nicotine and alcohol differ, it is likely that the mechanisms of increasing nicotine preference may not be identical to that of increasing alcohol preference. Stimulation of preference of yet other drugs may again be different -representing one aspect of drug specificity of reward mechanisms.

Integrated Management of Physician-delivered Alcohol Care for Tuberculosis Patients: Design and Implementation

BACKGROUND

While the integration of alcohol screening, treatment, and referral in primary care and other medical settings in the U.S. and worldwide has been recognized as a key health care priority, it is not routinely done. In spite of the high co-occurrence and excess mortality associated with alcohol use disorders (AUDs) among individuals with tuberculosis (TB), there are no studies evaluating effectiveness of integrating alcohol care into routine treatment for this disorder.

METHODS

We designed and implemented a randomized controlled trial (RCT) to determine the effectiveness of integrating pharmacotherapy and behavioral treatments for AUDs into routine medical care for TB in the Tomsk Oblast Tuberculosis Service (TOTBS) in Tomsk, Russia. Eligible patients are diagnosed with alcohol abuse or dependence, are newly diagnosed with TB, and initiating treatment in the TOTBS with Directly Observed Therapy-Short Course (DOTS) for TB. Utilizing a factorial design, the Integrated Management of Physician-delivered Alcohol Care for Tuberculosis Patients (IMPACT) study randomizes eligible patients who sign informed consent into 1 of 4 study arms: (1) Oral Naltrexone + Brief Behavioral Compliance Enhancement Therapy (BBCET) + treatment as usual (TAU), (2) Brief Counseling Intervention (BCI) + TAU, (3) Naltrexone + BBCET + BCI + TAU, or (4) TAU alone.

RESULTS

Utilizing an iterative, collaborative approach, a multi-disciplinary U.S. and Russian team has implemented a model of alcohol management that is culturally appropriate to the patient and TB physician community in Russia. Implementation to date has achieved the integration of routine alcohol screening into TB care in Tomsk; an ethnographic assessment of knowledge, attitudes, and practices of AUD management among TB physicians in Tomsk; translation and cultural adaptation of the BCI to Russia and the TB setting; and training and certification of TB physicians to deliver oral naltrexone and brief counseling interventions for alcohol abuse and dependence as part of routine TB care. The study is successfully enrolling eligible subjects in the RCT to evaluate the relationship of integrating effective pharmacotherapy and brief behavioral intervention on TB and alcohol outcomes, as well as reduction in HIV risk behaviors.

CONCLUSIONS

The IMPACT study utilizes an innovative approach to adapt 2 effective therapies for treatment of alcohol use disorders to the TB clinical services setting in the Tomsk Oblast, Siberia, Russia, and to train TB physicians to deliver state of the art alcohol pharmacotherapy and behavioral treatments as an integrated part of routine TB care. The proposed treatment strategy could be applied elsewhere in Russia and in other settings where TB control is jeopardized by AUDs. If demonstrated to be effective, this model of integrating alcohol interventions into routine TB care has the potential for expanded applicability to other chronic co-occurring infectious and other medical conditions seen in medical care settings.

Binge drinking upregulates accumbens mGluR5-Homer2-PI3K signaling: functional implications for alcoholism

The glutamate receptor-associated protein Homer2 regulates alcohol-induced neuroplasticity within the nucleus accumbens (NAC), but the precise intracellular signaling cascades involved are not known. This study examined the role for NAC metabotropic glutamate receptor (mGluR)-Homer2-phosphatidylinositol 3-kinase (PI3K) signaling in regulating excessive alcohol consumption within the context of the scheduled high alcohol consumption (SHAC) model of binge alcohol drinking. Repeated bouts of binge drinking ( approximately 1.5 g/kg per 30 min) elevated NAC Homer2a/b expression and increased PI3K activity in this region. Virus-mediated knockdown of NAC Homer2b expression attenuated alcohol intake, as did an intra-NAC infusion of the mGluR5 antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine hydrochloride] (0.1-1 microg/side) and the PI3K antagonist wortmannin (50 ng/side), supporting necessary roles for mGluR5/Homer2/PI3K in binge alcohol drinking. Moreover, when compared with wild-type littermates, transgenic mice with an F1128R point mutation in mGluR5 that markedly reduces Homer binding exhibited a 50% reduction in binge alcohol drinking, which was related to reduced NAC basal PI3K activity. Consistent with the hypothesis that mGluR5-Homer-PI3K signaling may be a mechanism governing excessive alcohol intake, the "anti-binge" effects of MPEP and wortmannin were not additive, nor were they observed in the mGluR5(F1128R) transgenic mice. Finally, mice genetically selected for a high versus low SHAC phenotype differed in NAC mGluR, Homer2, and PI3K activity, consistent with the hypothesis that augmented NAC mGluR5-Homer2-PI3K signaling predisposes a high binge alcohol-drinking phenotype. Together, these data point to an important role for NAC mGluR5-Homer2-PI3K signaling in regulating binge-like alcohol consumption that has relevance for our understanding of the neurobiology of alcoholism and its pharmacotherapy.

The effect of 12-week open-label memantine treatment on cognitive function improvement in patients with alcohol-related dementia

There is compelling evidence that alcohol-induced neurotoxicity is related to glutamate excitotoxicity. It was hypothesized that the low-affinity NMDA receptor antagonist memantine would improve the cognitive function of patients with alcoholic dementia. The aim of this study was to test this hypothesis and to evaluate the effect of memantine on the cognitive improvement of patients with alcohol-related dementia (ARD). The study was designed as a 12-wk open-label study investigating the efficacy of 20 mg memantine, a low-affinity NMDA receptor antagonist, as a treatment for cognitive and behavioural problems in 19 patients with probable ARD according to the criteria for ARD proposed by Oslin and colleagues. The CERAD-K (Consortium to Establish a Registry for Alzheimer's Disease - Korean version) and several clinical assessment scales were completed before and after the 12-wk memantine treatment period. Significant improvements in the mean scores from baseline to final assessment were observed in the Global Deterioration Scale (p<0.05), Brief Psychiatric Rating Scale (p<0.01), Geriatric Quality of Life - Dementia scale (p<0.01) and Neuropsychiatric Inventory (p<0.01) at the end of week 12. The CERAD-K subscales of word list recall (p<0.05), word list recognition (p<0.05), time orientation (p<0.01), drawing an interlocking pentagon (p<0.05), and the total MMSE-K (Mini Mental State Examination - Korean version) scores (p<0.01) of the patients all showed significant improvement following the memantine trial. In this open-label study, patients with ARD treated with 20 mg/d memantine for 12 wk showed improvement on global cognition, quality of life and behavioural symptoms. The result of this study suggests the possible usefulness of memantine for the treatment of ARD. As this was an open-label study, the possibility that participants improved cognitively on their own due to protracted abstinence from alcohol cannot be discounted.

Acute effects of acamprosate and MPEP on ethanol Drinking-in-the-Dark in male C57BL/6J mice

BACKGROUND

Recently, a simple procedure in mice, Drinking-in-the-Dark (DID), was hypothesized to have value for medication development for human alcoholism. In DID, mice are offered intermittent, limited access to ethanol over a series of days during the dark phase that results in rapid drinking to intoxication in predisposed genotypes.

METHODS

We measured the effects of acamprosate or MPEP, metabotropic glutamate 5 receptor (mGluR5) antagonist, on intake of 20% ethanol, plain tap water or 10% sugar water using the DID procedure in male C57BL/6J mice.

RESULTS

Acamprosate (100, 200, 300, or 400 mg/kg) dose dependently decreased ethanol drinking with 300 mg/kg reducing ethanol intake by approximately 20% without affecting intake of plain water or 10% sugar water. MPEP (1, 3, 5, 10, 20, or 40 mg/kg) was more potent than acamprosate with 20 mg/kg reducing ethanol intake by approximately 20% and for longer duration without affecting intake of plain water or 10% sugar water.

CONCLUSIONS

These results support the hypothesis that mGluR5 signaling plays a role in excessive ethanol intake in DID and suggest DID may have value for screening novel compounds that reduce overactive glutamate signaling for potential pharmaceutical treatment of excessive ethanol drinking behavior.

Topiramate attenuates the stress-induced increase in alcohol consumption and preference in male C57BL/6J mice

Stress increases the risk for alcohol abuse and relapse behaviors. However, there are hardly any medications to counteract stress-induced alcoholism and relapse behaviors. The present study examined the effects of topiramate (intraperitoneal injections of 10, 20, and 30 mg/kg) in its ability to attenuate alcohol consumption on exposure to restraint stress in C57BL/6J mice on a 2-choice test procedure. Mice were either restrained for 1h/day for 5 successive days or left unrestrained. Subsequently, the effects of topiramate were studied in post-restraint days. Results showed that restrained animals increased alcohol consumption and alcohol preference significantly compared to control group on day 5. On post-restraint days, topiramate reduced alcohol consumption and alcohol preference on days 2-5 compared to saline. This experiment suggests that one mechanism of topiramate in reducing alcohol consumption and alcohol preference may involve an interaction with stress.

Hepatitis infection in the treatment of opioid dependence and abuse

Many new and existing cases of viral hepatitis infections are related to injection drug use. Transmission of these infections can result directly from the use of injection equipment that is contaminated with blood containing the hepatitis B or C virus or through sexual contact with an infected individual. In the latter case, drug use can indirectly contribute to hepatitis transmission through the dis-inhibited at-risk behavior, that is, unprotected sex with an infected partner. Individuals who inject drugs are at-risk for infection from different hepatitis viruses, hepatitis A, B, or C. Those with chronic hepatitis B virus infection also face additional risk should they become co-infected with hepatitis D virus. Protection from the transmission of hepatitis viruses A and B is best achieved by vaccination. For those with a history of or who currently inject drugs, the medical management of viral hepatitis infection comprising screening, testing, counseling and providing care and treatment is evolving. Components of the medical management of hepatitis infection, for persons considering, initiating, or receiving pharmacologic therapy for opioid addiction include: testing for hepatitis B and C infections; education and counseling regarding at-risk behavior and hepatitis transmission, acute and chronic hepatitis infection, liver disease and its care and treatment; vaccination against hepatitis A and B infection; and integrative primary care as part of the comprehensive treatment approach for recovery from opioid abuse and dependence. In addition, participation in a peer support group as part of integrated medical care enhances treatment outcomes. Liver disease is highly prevalent in patient populations seeking recovery from opioid addiction or who are currently receiving pharmacotherapy for opioid addiction. Pharmacotherapy for opioid addiction is not a contraindication to evaluation, care, or treatment of liver disease due to hepatitis virus infection. Successful pharmacotherapy for opioid addiction stabilizes patients and improves patient compliance to care and treatment regimens as well as promotes good patient outcomes. Implementation and integration of effective hepatitis prevention programs, care programs, and treatment regimens in concert with the pharmacological therapy of opioid addiction can reduce the public health burdens of hepatitis and injection drug use.

Effects of acamprosate on neuronal receptors and ion channels expressed in Xenopus oocytes

BACKGROUND

Acamprosate (calcium acetylhomotaurinate) has proven to be a moderately effective pharmacological adjunct for the treatment of alcoholism. However, the central nervous system mechanism by which acamprosate reduces alcohol relapse remains unclear. Here we survey a number of metabotropic receptors, ligand-gated ion channels, and voltage-gated ion channels, to determine if acamprosate has actions at these sites in the central nervous system.

METHODS

Xenopus oocytes were injected with cDNAs or cRNAs encoding metabotropic glutamate receptors 1 and 5, M1 muscarinic receptors, glycine alpha1 homomeric and alpha1beta1 heteromeric receptors, gamma-aminobutyric acid A (GABA(A)alpha4beta3delta, alpha4beta3gamma2s, and alpha1beta2gamma2s) receptors, vanilloid receptor 1, and various combinations of alpha and beta subunits of voltage-gated Na+ channels. Electrophysiological responses were measured using two-electrode voltage clamp parameters after activation with agonists or voltage steps (for the voltage-gated channels). Acamprosate (0.1 to 100 microM) was pre-applied for 1 minute, followed by co-application with agonist. Acamprosate was also applied with ethanol to determine if it altered ethanol responses at some of these receptors and channels.

RESULTS

None of the receptors or ion channels responded to acamprosate alone. Acamprosate also failed to alter the activation of receptors or channels by agonists or after activation of voltage-gated channels. There was no effect of acamprosate on ethanol responses at GABA(A)alpha1beta2gamma2s receptors or Na+ channels.

CONCLUSIONS

Acamprosate does not significantly modulate the function of these receptors and ion channels at clinically relevant concentrations. Thus, the clinical effectiveness of acamprosate in the treatment of alcoholism is not likely due to direct effects on these receptors or ion channels.

A microdialysis study of extracellular levels of acamprosate and naltrexone in the rat brain following acute and repeated administration

Acamprosate and naltrexone are widely used in the treatment of alcoholism. However, numerous studies in rodents have shown differential effects of these compounds on alcohol consumption and/or relapse-like behavior following acute versus repeated administration. In order to determine if these differential behavioral effects could be attributable to changes in extracellular levels of these compounds, we used in vivo microdialysis to monitor extracellular levels of acamprosate and naltrexone in the rat medial prefrontal cortex following acute and repeated intraperitoneal administration. For acute treatment, animals received a single administration of acamprosate (100 or 300 mg/kg) or naltrexone (1 or 3 mg/kg). For repeated treatment, animals received once daily treatment with saline, acamprosate (300 mg/kg) or naltrexone (3 mg/kg) for 10 days before a subsequent challenge with the compound according to their respective pretreatment group. Dialysate levels of acamprosate and naltrexone were analyzed by liquid chromatography-tandem mass spectrometry and high performance liquid chromatography, respectively. Following acute administration, peak dialysate concentrations of each compound were dose-dependent, observed within 1 hour of administration, and were found to be in the low micromolar range for acamprosate and in the low to mid-nanomolar range for naltrexone. Pretreatment with acamprosate, but not naltrexone, for 10 days resulted in higher dialysate concentrations of the compound relative to saline-pretreated controls. Thus, repeated administration of acamprosate, but not naltrexone, results in augmented extracellular levels of the compound in the brain relative to saline-pretreated controls, which may explain the need for repeated administration of acamprosate in order to observe effects on alcohol consumption and/or relapse.

The effect of acamprosate on alcohol and food craving in patients with alcohol dependence

INTRODUCTION

The balance between inhibitory (gamma aminobutyric acid; GABAergic) and excitatory (glutamatergic) neurotransmission is thought to be associated with craving for alcohol and food. The anticraving effect of acamprosate is thought to be mediated through modifying the balance of GABA and glutamate. Recent studies in animals have suggested that acamprosate may have non-selective effects on craving for both alcohol and food.

METHODS

The influence of acamprosate for reducing craving for alcohol and food was assessed in 204 in-patients with alcohol dependence (96 patients treated with acamprosate, PWA; 108 patients were not treated PNA) was assessed at baseline and following 1, 2, and 4 weeks of treatment.

RESULTS

There was a significant reduction in craving for alcohol over 4 weeks of treatment in both PWA and PNA groups, but without significant group differences. In contrast, a reduction in food craving was observed only in the PWA group. In addition, there was a significant increase of body mass index (BMI) in the PNA group but not the PWA group over the 4-week period.

DISCUSSION

These results demonstrate acamprosate nonselective effects on craving for drinking and eating in alcoholic patients.

Acamprosate in the treatment of alcohol dependence: clinical and economic considerations

Acamprosate has been commercially available in the USA since 2004 to treat alcohol dependence. Its safety and efficacy have been demonstrated in a number of clinical trials worldwide, which overall have shown significant improvements in abstinence compared with placebo. As with all alcoholism pharmacotherapies, acamprosate is used in conjunction with psychosocial interventions. One frequently described mechanism stipulates that acamprosate supports abstinence by normalizing the often protracted dysregulation of NMDA-mediated glutamatergic neurotransmission that follows chronic heavy alcohol use and withdrawal. This article reviews the clinical safety and efficacy of acamprosate, as well as results from recent pharmacoeconomic and human laboratory studies. These data elucidate the economic benefits of acamprosate, as well as its effects on cognition and alcohol-related sleep disturbances.