Clinical and biological moderators of response to naltrexone in alcohol dependence: a systematic review of the evidence

Integrated and collaborative care across the spectrum of alcohol-associated liver disease and alcohol use disorder

The public health impact of alcohol-associated liver disease (ALD), a serious consequence of problematic alcohol use, and alcohol use disorder (AUD) is growing, with ALD becoming a major cause of alcohol-associated death overall and the leading indication for liver transplantation in the United States. Comprehensive care for ALD often requires treatment of AUD. Although there is a growing body of evidence showing that AUD treatment is associated with reductions in liver-related morbidity and mortality, only a minority of patients with ALD and AUD receive this care. Integrated and collaborative models that streamline both ALD and AUD care for patients with ALD and AUD are promising approaches to bridge this treatment gap and rely on multidisciplinary and interprofessional teams and partnerships. Here, we review the role of AUD care in ALD treatment, the effects of AUD treatment on liver-related outcomes, the impact of comorbid conditions such as other substance use disorders, obesity, and metabolic syndrome, and the current landscape of integrated and collaborative care for ALD and AUD in various treatment settings. We further review knowledge gaps and unmet needs that remain, including the role of precision medicine, the application of harm reduction approaches, the impact of health disparities, and the need for additional AUD treatment options, as well as further efforts to support implementation and dissemination.

Current Understanding of Compulsive Sexual Behavior Disorder and Co-occurring Conditions: What Clinicians Should Know about Pharmacological Options

Compulsive sexual behavior disorder (CSBD) has recently been recognized as a psychiatric disorder. Pharmacological treatments for CSBD have received little study and thus have limited empirical support. The main objective of the present work is to review existing literature on the efficacy of different drugs on the symptomatology of CSBD, including the subtype of problematic pornography use (PPU). The main pharmacological approaches to treating CSBD have included opioid antagonists (naltrexone and nalmefene), selective serotonin reuptake inhibitors (paroxetine, citalopram, fluoxetine, and sertraline), mood stabilizers (topiramate), tricyclic antidepressants (clomipramine), serotonin antagonist and reuptake inhibitors (nefazodone), and N-acetylcysteine. Since people with CSBD may experience different co-occurring disorders, these should be considered when choosing the best pharmacological treatment. Pharmacological therapy for CSBD/PPU has been suggested as an adjunct to psychological therapies, which, for the moment, have the most empirical evidence. However, to evaluate the efficacy of most of the drugs presented in this narrative review, data to date have only been available from case studies. Thus, empirical support is scant and generalizability of results is limited, highlighting the need for more research in this area.

Obesity: a gender-view

PURPOSE

There is a growing awareness of the importance of understanding gender differences in obesity. The aim of this short review was to revise the current evidence on anthropometric characteristics and nutritional and pharmacological aspects of obesity from a gender perspective.

METHODS

A literature search within PubMed was performed. Selected publications related to obesity and gender differences were reviewed.

RESULTS

The prevalence of obesity among men is higher than in women, but women have a higher percentage of body fat content compared to men, and gender appears to be an important factor in the manifestation of central (android) or peripheral (gynoid) obesity. In addition, while in most clinical trials, women are still underrepresented, in clinical registration trials of anti-obesity drugs, women are commonly up-represented and gender-specific analysis is uncommon. Considering that adipose tissue is one of the factors affecting the volume of distribution of many drugs, mainly lipophilic drugs, gender differences might be expected in the pharmacokinetics and pharmacodynamics of anti-obesity drugs. Indeed, although Liraglutide 3 mg, a long-acting glucagon-like peptide-1 receptor agonist, and naltrexone/bupropion display lipophilic properties, currently, a gender-dose adjustment for both these drugs administration is not recommended. In addition, despite that predicted responders to treatment offer substantial opportunities for efficient use, especially of expensive new therapies, such as anti-obesity drugs, data on gender differences to identify early responders to both these have not yet been investigated. Finally, bariatric surgery gender disparity reflects healthcare practices. Weight loss similar, but differing effects: women need more correction and face psychology challenges; men have worse physiology and fewer comorbidity improvements.

CONCLUSION

Gender differences exist in obesity prevalence and phenotype, body fat distribution, drug efficacy, clinical trial representation, and different secondary effects of bariatric surgery. Gender is an important variable in obesity analysis.

Naltrexone engages a brain reward network in the presence of reward-predictive distractor stimuli in males

The non-selective opioid receptor antagonist, naltrexone is one of the most prescribed medications for treating alcohol and opioid addiction. Despite decades of clinical use, the mechanism(s) by which naltrexone reduces addictive behavior remains unclear. Pharmaco-fMRI studies to date have largely focused on naltrexone's impact on brain and behavioral responses to drug or alcohol cues or on decision-making circuitry. We hypothesized that naltrexone's effects on reward-associated brain regions would associate with reduced attentional bias (AB) to non-drug, reward-conditioned cues. Twenty-three adult males, including heavy and light drinkers, completed a two-session, placebo-controlled, double-blind study testing the effects of acute naltrexone (50 mg) on AB to reward-conditioned cues and neural correlates of such bias measured via fMRI during a reward-driven AB task. While we detected significant AB to reward-conditioned cues, naltrexone did not reduce this bias in all participants. A whole-brain analysis found that naltrexone significantly altered activity in regions associated with visuomotor control regardless of whether a reward-conditioned distractor was present. A region-of-interest analysis of reward-associated areas found that acute naltrexone increased BOLD signal in the striatum and pallidum. Moreover, naltrexone effects in the pallidum and putamen predicted individual reduction in AB to reward-conditioned distractors. These findings suggest that naltrexone's effects on AB primarily reflect not reward processing per se, but rather top-down control of attention. Our results suggest that the therapeutic actions of endogenous opioid blockade may reflect changes in basal ganglia function enabling resistance to distraction by attractive environmental cues, which could explain some variance in naltrexone's therapeutic efficacy.

Mifepristone as a pharmacological intervention for stress-Induced alcohol craving: a translational crossover randomized trial

Preclinical and clinical work suggests that mifepristone (glucocorticoid receptor antagonist), may be a viable treatment for alcohol use disorder (AUD). The aim of this work was to translate our preclinical mifepristone study using yohimbine (α2 receptor antagonist) stress-induced reinstatement of alcohol-seeking to a clinical setting. This was a Phase 1/2, outpatient, cross-over, randomized, double-blind, placebo-controlled trial with non-treatment-seeking individuals with AUD ( N =32). We investigated the safety, alcohol craving and consumption after oral administration of mifepristone (600mg daily for a week) in a human laboratory study comprised of administration of yohimbine in a cue-reactivity procedure and alcohol self-administration. Outcomes were assessed using Generalized Estimating Equations and mediation and moderation analyses assessed mechanisms of action and precision medicine targets. We did not observe serious adverse events related to the study drugs or study procedure and mild to moderate non-serious adverse events were reported by both study conditions. Also, there was no statistically-significant difference between the mifepristone and placebo in the hemodynamic response, alcohol subjective effects and pharmacokinetics parameters. Mifepristone significantly reduced alcohol craving and increased cortisol levels. Mifepristone-induced cortisol increase was not a mediator of alcohol craving. Moderation analysis with family history density of AUD (FHDA) and mifepristone, suggested that reduced craving was present in individuals with low , but not high FHDA. Mifepristone, compared to placebo, did not reduce alcohol consumption in the laboratory or in a naturalistic setting. This study successfully translated a preclinical paradigm to a human laboratory study confirming safety, tolerability and efficacy of mifepristone in an alcohol paradigm. Mediation analysis showed that the effect of mifepristone on craving was not related to mifepristone-induced increases in cortisol and moderation of FHDA suggested the importance of evaluating AUD endophenotypes for pharmacotherapies.

Clinical trial registration

Clinicaltrials.gov ; NCT02243709.

IND/FDA

121984, mifepristone and yohimbine (Holder: Haass-Koffler).

Hazardous drinking and alcohol use disorders

Alcohol is one of the most widely consumed psychoactive drugs globally. Hazardous drinking, defined by quantity and frequency of consumption, is associated with acute and chronic morbidity. Alcohol use disorders (AUDs) are psychiatric syndromes characterized by impaired control over drinking and other symptoms. Contemporary aetiological perspectives on AUDs apply a biopsychosocial framework that emphasizes the interplay of genetics, neurobiology, psychology, and an individual's social and societal context. There is strong evidence that AUDs are genetically influenced, but with a complex polygenic architecture. Likewise, there is robust evidence for environmental influences, such as adverse childhood exposures and maladaptive developmental trajectories. Well-established biological and psychological determinants of AUDs include neuroadaptive changes following persistent use, differences in brain structure and function, and motivational determinants including overvaluation of alcohol reinforcement, acute effects of environmental triggers and stress, elevations in multiple facets of impulsivity, and lack of alternative reinforcers. Social factors include bidirectional roles of social networks and sociocultural influences, such as public health control strategies and social determinants of health. An array of evidence-based approaches for reducing alcohol harms are available, including screening, pharmacotherapies, psychological interventions and policy strategies, but are substantially underused. Priorities for the field include translating advances in basic biobehavioural research into novel clinical applications and, in turn, promoting widespread implementation of evidence-based clinical approaches in practice and health-care systems.

Clinical moderators of response to nalmefene in a randomized-controlled trial for alcohol dependence: An exploratory analysis

BACKGROUND

Nalmefene is the only medication marketed to reduce the consumption of alcohol in patients with alcohol dependence, but it remains unclear which patients could most benefit from it. This study aimed to identify clinical moderators that affect treatment response to nalmefene in patients with alcohol dependence.

METHODS

In a multicenter, randomized, controlled, double-blind, phase 3 study of nalmefene on Japanese patients with alcohol dependence, the relationship between the reduction of heavy drinking days (HDD) and total alcohol consumption (TAC) at 12 and 24 weeks of treatment and baseline variables of the participants were analyzed in a linear regression and multiple adjusted analysis.

RESULTS

Age < 65, no family history of problem drinking, age at onset of problem drinking ≥ 25, and not currently smoking were possible positive moderators. Nalmefene showed a significant HDD reduction in patients with age < 65 or no family history of problem drinking, and a significant TAC reduction in patients with age at onset of problem drinking ≥ 25 or who were not currently smoking. After multiple adjusted analyses, age < 65 (p = .028), no family history of problem drinking (p = .047), and age at onset of problem drinking ≥ 25 (p = .030) were statistically significant. Not currently smoking (p = .071) was marginally significant. In combination, these moderators indicated synergistic effects.

CONCLUSIONS

Alcohol-dependent patients with favorable prognostic factors such as non-smoking status, no family history of problem drinking, and a late-onset of problem drinking selectively benefit from nalmefene. Further research is needed to validate these exploratory results.

Using machine learning to predict heavy drinking during outpatient alcohol treatment

BACKGROUND

Accurate clinical prediction supports the effective treatment of alcohol use disorder (AUD) and other psychiatric disorders. Traditional statistical techniques have identified patient characteristics associated with treatment outcomes. However, less work has focused on systematically leveraging these associations to create optimal predictive models. The current study demonstrates how machine learning can be used to predict clinical outcomes in people completing outpatient AUD treatment.

METHOD

We used data from the COMBINE multisite clinical trial (n = 1383) to develop and test predictive models. We identified three priority prediction targets, including (1) heavy drinking during the first month of treatment, (2) heavy drinking during the last month of treatment, and (3) heavy drinking between weekly/bi-weekly sessions. Models were generated using the random forest algorithm. We used "leave sites out" partitioning to externally validate the models in trial sites that were not included in the model training. Stratified model development was used to test for sex differences in the relative importance of predictive features.

RESULTS

Models predicting heavy alcohol use during the first and last months of treatment showed internal cross-validation area under the curve (AUC) scores ranging from 0.67 to 0.74. AUC was comparable in the external validation using data from held-out sites (AUC range = 0.69 to 0.72). The model predicting between-session heavy drinking showed strong classification accuracy in internal cross-validation (AUC = 0.89) and external test samples (AUC range = 0.80 to 0.87). Stratified analyses showed substantial sex differences in optimal feature sets.

CONCLUSION

Machine learning techniques can predict alcohol treatment outcomes using routinely collected clinical data. This technique has the potential to greatly improve clinical prediction accuracy without requiring expensive or invasive assessment methods. More research is needed to understand how best to deploy these models.

Genetic contributions to alcohol use disorder treatment outcomes: a genome-wide pharmacogenomics study

Naltrexone can aid in reducing alcohol consumption, while acamprosate supports abstinence; however, not all patients with alcohol use disorder (AUD) benefit from these treatments. Here we present the first genome-wide association study of AUD treatment outcomes based on data from the COMBINE and PREDICT studies of acamprosate and naltrexone, and the Mayo Clinic CITA study of acamprosate. Primary analyses focused on treatment outcomes regardless of pharmacological intervention and were followed by drug-stratified analyses to identify treatment-specific pharmacogenomic predictors of acamprosate and naltrexone response. Treatment outcomes were defined as: (1) time until relapse to any drinking (TR) and (2) time until relapse to heavy drinking (THR; ≥ 5 drinks for men, ≥4 drinks for women in a day), during the first 3 months of treatment. Analyses were performed within each dataset, followed by meta-analysis across the studies (N = 1083 European ancestry participants). Single nucleotide polymorphisms (SNPs) in the BRE gene were associated with THR (min p = 1.6E-8) in the entire sample, while two intergenic SNPs were associated with medication-specific outcomes (naltrexone THR: rs12749274, p = 3.9E-8; acamprosate TR: rs77583603, p = 3.1E-9). The top association signal for TR (p = 7.7E-8) and second strongest signal in the THR (p = 6.1E-8) analysis of naltrexone-treated patients maps to PTPRD, a gene previously implicated in addiction phenotypes in human and animal studies. Leave-one-out polygenic risk score analyses showed significant associations with TR (p = 3.7E-4) and THR (p = 2.6E-4). This study provides the first evidence of a polygenic effect on AUD treatment response, and identifies genetic variants associated with potentially medication-specific effects on AUD treatment response.

Exploring the Role of Alcohol Metabolizing Genotypes in a 12-Week Clinical Trial of Naltrexone for Alcohol Use Disorder

Background: The efficacy of naltrexone in the treatment of alcohol use disorder (AUD) has been associated with a set of variables not directly related with the expression of opioid receptors. All the variables have been found to be highly associated with AUD itself or more severe clinical levels of AUD. Objectives: Given the high association between alcohol metabolizing enzymes (AME) and the outcome of AUD, the present study aims to investigate the role of AME genotype variants in the treatment of AUD with naltrexone. Methods: We carried out a 12-week longitudinal clinical trial based on the treatment of AUD patients with naltrexone (N = 101), stratified by different alcohol metabolization genotypes. Genotyping was performed after the inclusion of the patients in the study, based on the individual presence of single nucleotide polymorphisms (SNPs) in the ADH (alcohol dehydrogenase)1B (ADH1B*2 and ADH1B*3), ADH1C (ADHC*1) and ALDH (aldehyde dehydrogenase) 2 (ALDH2*2) genes. The outcome of alcohol use has been monitored employing the timeline follow-back during the treatment. Results: The ADH1C*1 (Ile350Val, rs698) and ALDH2*2 (Glu504Lys, rs671) polymorphisms were associated with a better response to naltrexone treatment, whereas the ADH1B*3 (Arg370Cys, rs2066702) allelic variant showed a negative outcome. Conclusions: The present study explores a genomic setting for the treatment of AUD with naltrexone. According to our findings, the association between ADH1C*1 and ALDH2*2 variants and better outcomes suggests a successful treatment, whereas the ADH1B*3 mutated allele might lead to an unsuccessful treatment. Further studies should be performed to investigate the relationship between alcohol metabolizing genotypes, the family history of alcohol use disorders and the effect of naltrexone on the outcomes. Genotyping may be a valuable tool for precision-medicine and individualized approach, especially in the context of alcohol use disorders. The small number of subjects was the main limitation of the present study.

Participants' Treatment Perspectives on a Clinical Trial on the Use of Extended-Release Naltrexone for Substance Use Disorders: Considerations for Future Clinical Research

OBJECTIVES

We undertook this study to understand participants' perceptions of their assigned treatment in a randomized control trial examining the use of extended-release naltrexone versus treatment as usual for substance use disorders.

METHODS

Semi-structured qualitative interviews among 22 prospective and actual participants in a larger clinical trial examining the feasibility of extended-release naltrexone for both opioid and alcohol use disorders among people living with HIV. Interviews were transcribed, coded, and analyzed thematically.

RESULTS

Participants described their study experience as mostly positive, but also concurrently held or developed study medication apprehensions and misperceptions. First, some participants described apprehension, lack of control, and uneasiness regarding their assigned treatment. Second, some participants perceived their treatment as "placebos" and/or were convinced that their treatment was ineffective, shaping perceptions of impact on their substance use. Third, some participants perceived study treatments as cure-alls for substance use disorders.

CONCLUSIONS

Participant perceptions of trial interventions may frame their experience and participation in clinical studies. These findings demonstrate the need for researchers and clinicians to consider how apprehension and a lack of medication receptivity may impact enrollment and participant autonomy. They also identify opportunities for greater community engagement in trial design and implementation in order to improve participant education about the nature of interventions and the potential of ongoing consent processes integrated throughout studies to promote participant understandings of study purposes and objectives.

Occupancy of the kappa opioid receptor by naltrexone predicts reduction in drinking and craving

The efficacy of naltrexone to treat alcohol use disorder (AUD) is modest. A better understanding of the neurobiology underlying naltrexone effects could optimize treatments. We evaluated the occupancy of the kappa opioid receptor (KOR) by naltrexone measured with [¹¹C]-LY2795050 positron emission tomography (PET) as a predictor of response to naltrexone. Response to naltrexone was defined as the difference in craving and the difference between the number of drinks consumed during an alcohol drinking paradigm (ADP) before and after 1 week of supervised 100 mg daily oral naltrexone. Forty-four (14 F) nontreatment seeking heavy drinkers meeting criteria for AUD were enrolled. Participants drank 47 ± 16 drinks per week and were balanced in family history of alcoholism (FH, 26 positive). High KOR occupancy (92 ± 1%) was achieved. Occupancy was negatively associated with number of years drinking (YOD) in FH positive, but not FH negative, participants (t_3,42 = 4.00, p = 0.0003). Higher KOR occupancy by naltrexone was associated with higher alcohol craving during the ADP (F_1,81 = 4.88, p = 0.030). The reduction in drinking after naltrexone was negatively associated with KOR occupancy, with significant effects of FH status (t_1,43 = -2.08, p = 0.044). A logistic regression model including KOR occupancy, YOD, and FH variables achieved an 84% prediction accuracy for ≥50% reduction in drinking. These results confirm that naltrexone binds at the KOR site and suggest that KOR occupancy by naltrexone may be related to clinical response. Based on our results, we propose that differential affinities for the mu and KOR could explain why lower doses of naltrexone can have greater clinical efficacy.

Machine learning prediction of blood alcohol concentration: a digital signature of smart-breathalyzer behavior

Excess alcohol use is an important determinant of death and disability. Machine learning (ML)-driven interventions leveraging smart-breathalyzer data may help reduce these harms. We developed a digital phenotype of long-term smart-breathalyzer behavior to predict individuals' breath alcohol concentration (BrAC) levels trained on data from a smart breathalyzer. We analyzed roughly one million datapoints from 33,452 users of a commercial smart-breathalyzer device, collected between 2013 and 2017. For validation, we analyzed the associations between state-level observed smart-breathalyzer BrAC levels and impaired-driving motor vehicle death rates. Behavioral, geolocation-based, and time-series-derived features were fed to an ML algorithm using training (70% of the cohort), development (10% of the cohort), and test (20% of the cohort) sets to predict the likelihood of a BrAC exceeding the legal driving limit (0.08 g/dL). States with higher average BrAC levels had significantly higher alcohol-related driving death rates, adjusted for the number of users per state B (SE) = 91.38 (15.16), p < 0.01. In the independent test set, the ML algorithm predicted the likelihood of a given user-initiated BrAC sample exceeding BrAC ≥ 0.08 g/dL, with an area under the curve (AUC) of 85%. Highly predictive features included users' prior BrAC trends, subjective estimation of their BrAC (or AUC = 82% without the self-estimate), engagement and self-monitoring, time since the last measure, and hour of the day. In conclusion, an ML algorithm successfully quantified a digital phenotype of behavior, predicting naturalistic BrAC levels exceeding 0.08 g/dL (a threshold associated with alcohol-related harm) with good discrimination capability. This result establishes a foundation for future research on precision behavioral medicine digital health interventions using smart breathalyzers and passive monitoring approaches.

A Critical Review of Alcohol Administration Guidelines in Laboratory Medication Screening Research: Is It Time to Include Treatment Seekers?

Human laboratory studies play an important role in alcohol use disorder (AUD) medication development. Medications that are found to be safe and effective during human laboratory screening will then move to more expensive clinical trials in patient populations. Given the gatekeeping role of human laboratory studies in the medication development pipeline, it is critical that these studies accurately forecast how pharmacotherapies will perform under true-to-life clinical conditions. On the other hand, the design of these studies also must adhere to ethical guidelines: certain aspects of clinical reality cannot be incorporated into screening studies because doing so might place the participant at risk for harm or breach other ethical guidelines. Conventions exist that guide the resolution of these conflicting ideals. This article considers the practice of recruiting non-treatment-seeking heavy drinkers to participate in laboratory screening studies. By convention, volunteers are excluded from laboratory screening studies that involve alcohol administration if they are deemed "treatment seeking," meaning that they recently stopped drinking or are motivated to do so. Although this common practice may reduce risk to participants, findings may not accurately predict medication effects on treatment seekers. Indeed, there is empirical evidence that treatment seekers differ from nontreatment seekers in their responses to medications (Neuropsychopharmacology 2017a; 42: 1776; Am J Drug Alcohol Abuse 2017b; 43: 703; J Psychiatr Res 2006; 40: 383). Here, we argue for the importance of recruiting treatment seekers for this research due to their qualitative difference from nontreatment seekers. We argue that these individuals should be the default population in human laboratory medication screening studies. We conclude by discussing 2 case examples of medication experiments led by our research groups that involved administering medications to treatment seekers.

Effects of ethanol, naltrexone, nicotine and varenicline in an ethanol and nicotine co-use model in Sprague-Dawley rats

BACKGROUND

As alcohol and nicotine use disorders are entwined, it may be possible to develop a single medication to treat both. We previously developed a model for ethanol (EtOH) and nicotine co-use in female selectively bred alcohol-preferring (P) rats. To model co-use in a genetically diverse population, we adapted the model to outbred Sprague-Dawley rats of both sexes and assessed the effect of drug pretreatments.

METHODS

In phase 1, rats were trained in a 2-bottle choice between water and a sweetened or unsweetened EtOH solution in operant chambers. In phase 2, rats were trained in nicotine self-administration under an increasing fixed ratio (FR) schedule with 2 bottles containing water or saccharin-sweetened EtOH also available. In phase 3, rats were pretreated with EtOH (0.5, 1.5 g/kg), naltrexone (0.3 mg/kg), nicotine (0.2, 0.6 mg/kg), varenicline (3.0 mg/kg) or vehicle before the session.

RESULTS

Sweetening the EtOH solution was required to obtain pharmacologically relevant levels of consumption in Phase 1, with males showing increased sweetened EtOH preference compared to females. In Phase 2, increasing the FR requirement for nicotine decreased nicotine infusions, but increased EtOH consumption. In Phase 3, EtOH, naltrexone, and nicotine failed to alter EtOH consumption; however, varenicline decreased both EtOH and nicotine intake.

CONCLUSIONS

The co-use model was successfully adapted to Sprague-Dawley rats by adding saccharin to the EtOH solution. In contrast to previous results in P rats, varenicline reduced both EtOH and nicotine intake, indicating it may be a useful monotherapy for co-use in a genetically diverse population.

Naltrexone Use in Treating Hypersexuality Induced by Dopamine Replacement Therapy: Impact of OPRM1 A/G Polymorphism on Its Effectiveness

Hypersexuality is a well-known adverse side effect of dopamine replacement therapy (DRT), and anti-craving drugs could be an effective therapeutic option. Our aim was to update the knowledge on this issue, particularly on the influence of an Opioid Receptor Mu 1 (OPRM1) genetic polymorphism. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We also analyzed a case of iatrogenic hypersexuality that occurred in a patient treated with DRT. An analysis of the OPRM1 gene was performed on said patient. Our search identified 597 publications, of which only 7 were included in the final data synthesis. All seven publications involved naltrexone use. Five of them were case reports. None of the publications mentioned DRT side effects, nor did they report genetic data. Regarding our case report, the introduction of naltrexone corresponded with the resolution of the patient’s hypersexuality. Moreover, the patient carried the A/G genotype, which has been reported to be associated with a stronger response to naltrexone for patients with an alcohol use disorder. Although studies are inconclusive so far, naltrexone could be an interesting therapeutic option for resistant hypersexuality due to DRT. Carrying the A/G genotype could help explain a good response to treatment.

OPRM1 Moderates Daily Associations of Naltrexone Adherence With Alcohol Consumption: Preliminary Evidence From a Mobile Health Trial

BACKGROUND

Initial evidence that OPRM1 genotype moderates the clinical response to naltrexone has not been replicated in prospective clinical trials. However, the use of traditional statistical analyses and clinical endpoints might limit sensitivity for studying pharmacogenetic associations, whereas the use of intensive daily assessments and person-centered analytic methods might increase sensitivity. This study leveraged person-centered analyses and daily measures of alcohol use, craving, and medication adherence to investigate OPRM1 as a moderator of changes in clinical outcomes during naltrexone treatment.

METHODS

Treatment-seeking participants with alcohol use disorder (n = 58; M_age  = 38 years; 71% male) provided daily cell phone reports of craving and consumption while taking naltrexone as part of a mobile health trial. Daily medication adherence was measured remotely using electronic pill cap recordings. Multilevel modeling and multilevel structural equation modeling analyses evaluated the hypotheses that OPRM1 genotype would moderate prospective reductions in daily alcohol use and craving, and would also moderate within-person associations of daily adherence with same-day craving and consumption.

RESULTS

OPRM1 genotype moderated the association of daily adherence with reduced same-day consumption (p = 0.007) and craving (p = 0.06), with these associations being stronger for participants with the 118G variant. OPRM1 genotype did not moderate changes in craving and consumption over time.

CONCLUSIONS

These findings suggest that high-density assessments and person-centered analytic approaches, including modeling within-person variation in medication adherence, could be advantageous for pharmacogenetic studies.

Mobile alcohol biosensors and pharmacotherapy development research

Recent advances in biosensor technology herald a major shift in the way alcohol use will be tracked in humans. Wearable biosensors can passively and continuously monitor wearers' alcohol consumption in real time. An important application of these biosensors is to improve the way medication for alcohol use disorder (AUD) is tested in clinical research. Both laboratory-based screening paradigms and clinical trials have methodological problems that impact their efficiency and predictive validity. Medication screening using laboratory-based methods is a resource-intensive assessment of a single episode of behavior in a non-representative setting. Clinical trials rely on participant self-report to document medication-induced changes in drinking behavior. This review describes how mobile biosensors can be leveraged to improve AUD medication development research. We first review the current state of alcohol biosensor technology with a focus on strengths and limitations of the devices. We describe how multiple biosensors can be combined to create a far more detailed record of drinking compared to single biosensor platforms. We then discuss each phase of the medication development pipeline in turn (i.e., phases 1-4) and describe how mobile biosensors can be incorporated in standard medication testing paradigms to improve efficiency and predictive validity. We conclude with discussion of challenges associated with using currently available biosensors for medication testing and recommendations for researchers wishing to incorporate alcohol biosensors into their own research.

The effects of nalmefene on emotion processing in alcohol use disorder - A randomized, controlled fMRI study

Nalmefene is a µ- and δ-opioid receptor antagonist and a partial κ-opioid receptor agonist. The drug is suggested to reduce the craving for, and the consumption of alcohol effectively, also alleviating anxiety and anhedonia. The present fMRI study is the first to investigate the processing of emotions as a possible mechanism of action of nalmefene in humans. Fifteen non-treatment-seeking participants suffering from alcohol use disorder (AUD) (24-66 years; 5 females) finished this randomized, placebo controlled, double blind study. Following a cross over design, participants received either a single dose nalmefene or a placebo, with an interval of one week between sessions. Using fMRI, we investigated neural reactivity during the presentation of emotional faces picture sets. Additionally, we performed a visual dot-probe task to detect nalmefene's effects on attentional bias. We detected an increase in the response to emotional faces in the supramarginal gyrus, the angular gyrus as well as the putamen in the nalmefene vs. placebo condition. However, contradictory to our initial hypotheses, amygdala activation was not altered significantly in the placebo condition - a limitation, which might be associated with a lack of activation in the placebo condition maybe due to the small sample size. Attentional bias analyses revealed an interaction effect by trend, which was driven by a significant effect in a sub-analysis showing increased attentional shift towards happy compared to fearful facial expressions under nalmefene. Nalmefene increased brain activation in areas responsible for empathy, social cognition and behavior, which might help alleviating the reinforcing properties of alcohol.

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 effects on subjective responses to alcohol in the human laboratory: A systematic review and meta-analysis

Naltrexone (NTX) has been widely studied for the treatment of alcohol use disorder with overall support for its efficacy. The mechanisms of action of naltrexone are thought to involve attenuation of the hedonic effects of alcohol and potentiation of its aversive effects. In order to provide a quantitative estimate of the effects of naltrexone on subjective response to alcohol, the aims of this meta-analytic review are to examine the effects of naltrexone across four domains of subjective response. Meta-analyses of naltrexone effects on alcohol craving (k = 16, N = 686), stimulation (k = 15, N = 675), sedation (k = 18, N = 777), and negative mood (k = 9, N = 281) suggested that under laboratory conditions and compared with placebo, naltrexone reduces craving (Hedges g = -0.252; SE = 0.054; 95% CI, -0.375 to -0.130; P < 0.01), reduces stimulation (g = -0.223; SE = 0.067; 95% CI, -0.372 to -0.074; P < 0.01), increases sedation (g = 0.251; SE = 0.064; 95% CI, 0.112-0.389; P < 0.01), and increases negative mood (g = 0.227; SE = 0.047; 95% CI, 0.100-0.354; P < 0.01). Results were robust when drinks per month and alcohol dose were added to the models as covariates. The effects of naltrexone varied by severity of alcohol use with medication effects on craving and stimulation being observed in sample of both heavy drinkers and AUD individuals. These results are consistent with the hypothesized mechanisms of action of NTX, although the effects are of small magnitude. This meta-analysis aggregates across multiple human laboratory studies of NTX's effects on subjective response to alcohol, providing a comprehensive summary of a key mechanism of NTX efficacy, namely, alteration of the subjective experience of alcohol.

Advances in the science and treatment of alcohol use disorder

Alcohol is a major contributor to global disease and a leading cause of preventable death, causing approximately 88,000 deaths annually in the United States alone. Alcohol use disorder is one of the most common psychiatric disorders, with nearly one-third of U.S. adults experiencing alcohol use disorder at some point during their lives. Alcohol use disorder also has economic consequences, costing the United States at least $249 billion annually. Current pharmaceutical and behavioral treatments may assist patients in reducing alcohol use or facilitating alcohol abstinence. Although recent research has expanded understanding of alcohol use disorder, more research is needed to identify the neurobiological, genetic and epigenetic, psychological, social, and environmental factors most critical in the etiology and treatment of this disease. Implementation of this knowledge in clinical practice and training of health care providers is also needed to ensure appropriate diagnosis and treatment of individuals suffering from alcohol use disorder.

Naltrexone Acutely Enhances Connectivity Between the Ventromedial Prefrontal Cortex and a Left Frontoparietal Network

BACKGROUND

Naltrexone, an opioid receptor antagonist that is Food and Drug Administration approved for treating alcohol use disorder (AUD), reduces alcohol craving and intake. Despite known pharmacological properties, little is known regarding the effects of naltrexone on neural circuit function. Thus, a data-driven examination of the neural effects of naltrexone in human subjects may offer novel insight into its treatment mechanisms.

METHODS

Twenty-one alcohol using males (22 to 39) participated in a double-blind, placebo-controlled crossover study of the effects of naltrexone on brain voxel-wise functional connectivity (FC) using intersubject FC correlation mapping. We first cross-correlated the time series from each gray matter voxel to produce a 6,356 × 6,356 FC matrix for each subject and session. We then subtracted the placebo FC matrix from the naltrexone FC matrix. To identify brain regions demonstrating significant reconfiguration of whole-brain FC patterns following naltrexone treatment, we statistically quantified the consistency of patterns of voxel FC changes across subjects. Permutation testing identified significant clusters of voxels undergoing significant reconfiguration. Using the identified clusters in a seed-based FC analysis, we then compared the FC patterns of affected brain areas on placebo versus naltrexone in a paired t-test. Ridge regression analyses identified self-report measures, including substance use, that significantly predicted individual differences in FC among naltrexone-modulated regions.

RESULTS

Two clusters in the rostral anterior cingulate cortex (rACC)/ventromedial prefrontal cortex (vmPFC) demonstrated significant modulation of FC by naltrexone. Using these 2 proximal clusters as a single seed, specific FC changes were identified in regions associated with a left frontoparietal network (increasing), as well as visual and motor regions (decreasing). Stronger FC between the rACC/vmPFC and this set of regions on placebo was associated with more external locus of control, whereas weaker connectivity was associated with greater substance use problems. Naltrexone strengthened these connections most among individuals who reported greater drinking to cope.

CONCLUSIONS

Enhancing connectivity between the rACC/vmPFC, implicated in alcohol craving, and components of a left frontoparietal network involved in executive control may represent an effective strategy for the treatment of AUD.

Gender-related issues in the pharmacology of new anti-obesity drugs

Four new medicines-liraglutide, lorcaserin, bupropion/naltrexone, and phentermine/topiramate-have been recently added to the pharmacological arsenal for obesity treatment and could represent important tools to manage this epidemic disease. To achieve satisfactory anti-obesity goals, the use of these new medicines should be optimized and tailored to specific patient subpopulations also by applying dose adjustments if needed. In the present review, we posit that gender could be among the factors influencing the activity of the new obesity drugs both because of pharmacokinetic and pharmacodynamic factors. Although evidence from premarketing clinical studies suggested that no dose adjustment by gender is necessary for any of these new medicines, these studies were not specifically designed to identify gender-related differences. This observation, together with the strong theoretical background supporting the hypothesis of a gender-dimorphic response, strongly call upon an urgent need of new real-life data on gender-related difference in the pharmacology of these new obesity drugs.

Efficacy of Extended-Release Naltrexone on HIV-Related and Drinking Outcomes Among HIV-Positive Patients: A Randomized-Controlled Trial

We sought to test the efficacy of extended-release naltrexone (XR-NTX) on HIV-related and drinking outcomes. From April 2011-February 2015, we conducted a 4-site randomized double-blind placebo controlled clinical trial involving 51 HIV-positive patients with heavy drinking and < 95% antiretroviral (ART) adherence. All participants received counseling. The primary outcome was proportion with ≥ 95% ART adherence. Secondary outcomes included HIV biomarkers, VACS Index score, and past 30-day heavy drinking days. Based on receipt of ≥ 5 injections, 23 participants were retained at 24 weeks. We did not detect an effect of XR-NTX on ART adherence (p = 0.38); undetectable HIV viral load (p = 0.26); CD4 cell count (p = 0.75) or VACS Index score (p = 0.70). XR-NTX was associated with fewer heavy drinking days (p = 0.03). While XR-NTX decreases heavy drinking days, we did not detect improvements in ART adherence or HIV outcomes. Strategies to improve retention in alcohol treatment and HIV-related outcomes among heavy drinking HIV-positive patients are needed.

Medication Development for Alcohol Use Disorder: A Focus on Clinical Studies

Compared to other medical disorders, including other brain diseases, the number of medications approved for alcohol use disorder (AUD) is very small. Disulfiram, naltrexone (oral and long-acting), and acamprosate are approved by the US Food and Drug Administration (FDA) to treat patients with AUD. These medications are also approved in other countries, including in Europe, where the European Medicines Agency (EMA) also approved nalmefene for AUD. Furthermore, baclofen was recently approved for AUD in France. These approved medications have small effect sizes, which are probably the consequence of the fact that they only work for some patients, yet a personalized approach to match the right medication with the right patient is still in its infancy. Therefore, research is needed to expand the armamentarium of medications that clinicians can use to treat their patients, as well as to better develop personalized approaches. This book chapter reviews other medications, beyond those approved by the FDA, that have shown efficacy in clinical trials, as well as medications which are still in the early stages of evaluation in human studies.

Real-time assessment of alcohol craving and naltrexone treatment responsiveness in a randomized clinical trial

INTRODUCTION

This secondary data analysis examined whether and how the dopamine receptor D₄ gene (DRD4) influenced naltrexone treatment responsiveness in a randomized clinical trial. We leveraged intensive experience sampling methods to test the hypothesis that craving recorded at drinking and non-drinking moments would mediate naltrexone effects on the likelihood of heavy drinking, but only among carriers of the DRD4 long (DRD4-L) allele.

METHODS

Participants (M_age=29.8years, SD=12.1) were non-treatment seeking heavy drinkers (n=104, 54.8% female, 61.5% alcohol dependent) randomized to 3weeks of daily naltrexone (50mg) or placebo. During these 3weeks, participants used handheld electronic devices to complete real-time reports of alcohol use and craving multiple times per day in their natural environments. This approach afforded intensive repeated assessment of focal variables and provided in-the-moment data to test whether craving when not drinking or early in drinking episodes explained naltrexone effects on drinking.

RESULTS

Moderated-mediation multilevel structural equation models showed that craving during non-drinking moments mediated the treatment effect of naltrexone on heavy drinking but only among carriers of the DRD4-L allele. The same pattern of associations was not shown when evaluating craving while participants were consuming alcoholic beverages.

CONCLUSIONS

Findings provide the first in vivo evidence that, among carriers of the DRD4-L allele, naltrexone blunts craving in real-world settings, and this effect in turn reduces the likelihood of heavy drinking. This work highlights the utility of EMA methods for elucidating how treatments work and further demonstrates the importance of genetic factors for understanding individual differences in pharmacotherapy responsiveness.

[Diagnosis, differential diagnosis and therapy of substance use disorders in general hospital (general section)]

Substance use disorders are becoming an increasingly significant problem in general hospitals and hence play a key role in consultation- and liaison psychiatry. Diverse psychotropic effects of various substances mimic psychiatric disorders. An alcohol intoxication can present depressive or manic symptoms, a cannabis delirium can present as a psychosis while stimulants use can suggest the diagnosis of an anxiety disorder. Obtaining dual diagnoses by identifying substance-induced and non-substance-induced psychopathologies is clinically challenging.The aim of this article is to systematically describe the psychopathology, pathophysiology and therapeutic options of substance-use disorders particularly relevant for consultation and liaison psychiatry.

Focusing on the Opioid System for Addiction Biomarker Discovery

Substance use disorders (SUD) and behavioral addictions are devastating conditions that impose a severe burden on all societies, and represent difficult challenges for clinicians. Therefore, biomarkers are urgently needed to help predict vulnerability, clinical course, and response to treatment. Here, we elaborate on the potential for addiction biomarker discovery of the opioid system, particularly within the emerging framework aiming to probe opioid function in peripheral tissues. Mu, delta, and kappa opioid receptors all critically regulate neurobiological and behavioral processes that define addiction, and are also targeted by major pharmacotherapies used in the management of patients with SUD. We propose that opioid biomarkers may have the potential to improve and guide diagnosis and therapeutic decisions in the addiction field.

Advances in Pharmacotherapy Development: Human Clinical Studies

For more than 25 years, researchers have made advances in developing medications to treat alcohol use disorder (AUD), highlighted by the US Food and Drug Administration's (FDA's) approval of disulfiram, naltrexone (oral and long-acting), and acamprosate. These medications are also approved in Europe, where the European Medicines Agency (EMA) recently added a fourth medication, nalmefene, for AUD. Despite these advances, today's medications have a small effect size, showing efficacy for only a limited number of individuals with AUD. However, a host of new medications, which act on variety of pharmacologic targets, are in the pipeline and have been evaluated in numerous human studies. This article reviews the efficacy and safety of medications currently being tested in human trials and looks at ongoing efforts to identify candidate compounds in human studies. As mentioned in the National Institute on Alcohol Abuse and Alcoholism's Strategic Plan 2017-2021 ( https://www.niaaa.nih.gov/sites/default/files/StrategicPlan_NIAAA_optimized_2017-2020.pdf ), medications development remains a high priority. By developing more effective and safe medications, and identifying those patients who will benefit the most from these treatments, we can provide clinicians with the tools they need to treat this devastating disorder, providing relief for patients and their families and markedly improving public health and safety.

Reward and relief dimensions of temptation to drink: construct validity and role in predicting differential benefit from acamprosate and naltrexone

Researchers have sought to distinguish between individuals whose alcohol use disorder (AUD) is maintained by drinking to relieve negative affect ('relief drinkers') and those whose AUD is maintained by the rewarding effects of alcohol ('reward drinkers'). As an opioid receptor antagonist, naltrexone may be particularly effective for reward drinkers. Acamprosate, which has been shown to down-regulate the glutamatergic system, may be particularly effective for relief drinkers. This study sought to replicate and extend prior work (PREDICT study; Glöckner-Rist et al. ) by examining dimensions of reward and relief temptation to drink and subtypes of individuals with distinct patterns of reward/relief temptation. We utilized data from two randomized clinical trials for AUD (Project MATCH, n = 1726 and COMBINE study, n = 1383). We also tested whether classes of reward/relief temptation would predict differential response to naltrexone and acamprosate in COMBINE. Results replicated prior work by identifying reward and relief temptation factors, which had excellent reliability and construct validity. Using factor mixture modeling, we identified five distinct classes of reward/relief temptation that replicated across studies. In COMBINE, we found a significant class-by-acamprosate interaction effect. Among those most likely classified in the high relief/moderate reward temptation class, individuals had better drinking outcomes if assigned to acamprosate versus placebo. We did not find a significant class-by-naltrexone interaction effect. Our study questions the orthogonal classification of drinkers into only two types (reward or relief drinkers) and adds to the body of research on moderators of acamprosate, which may inform clinical decision making in the treatment of AUD.

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 Double-Blind Randomized Placebo-Controlled Trial of Oral Naltrexone for Heavy-Drinking Smokers Seeking Smoking Cessation Treatment

BACKGROUND

Post hoc analyses of 2 randomized controlled trials suggest naltrexone may reduce alcohol use and improve smoking cessation outcomes among heavy drinkers receiving smoking cessation treatment. However, no studies have been conducted specifically to examine naltrexone for this purpose or to test whether naltrexone has benefit when added to smoking cessation counseling that explicitly addresses heavy drinking.

METHODS

We recruited heavy-drinking smokers from the community and randomized them to receive 10 weeks of either (i) 50 mg naltrexone (n = 75) or (ii) placebo (n = 75) daily. Participants received 6 weeks of transdermal nicotine patch and 6 sessions of counseling that addressed both heavy drinking and smoking. Participants were followed for 26 weeks after their target quit smoking date.

RESULTS

Across medication conditions, there were substantial reductions at follow-up in percent heavy drinking days (primary outcome) and average drinks per week (secondary outcome). However, participants receiving naltrexone did not differ significantly from those receiving placebo on percent heavy drinking days (effect size d = -0.04, 95% CI [-0.30, 0.22], p = 0.76) or average drinks per week (d = -0.09, 95% CI [-0.35, 0.18], p = 0.54) during follow-up. Naltrexone compared to placebo was not associated with a significant increase in smoking abstinence rates during follow-up, odds ratio = 0.93, 95% CI [0.46, 1.86], p = 0.83. The effect of naltrexone on these outcomes was not significantly moderated by current alcohol dependence or gender.

CONCLUSIONS

Results indicate that heavy-drinking smokers, including those with current alcohol dependence, can make substantial reductions in drinking in the context of smoking cessation treatment. However, this study provided no evidence that naltrexone is efficacious for enhancing reductions in drinking or improving smoking cessation in this population. Limitations of this study included lower-than-desired sample size and modest adherence to study medication.

A Systematic Review of Naltrexone for Attenuating Alcohol Consumption in Women with Alcohol Use Disorders

Several clinical trials have evaluated naltrexone as a treatment for alcohol use disorders (AUDs), but few have focused on women. The aim of this review was to systematically review and summarize the evidence regarding the impact of naltrexone compared to placebo for attenuating alcohol consumption in women with an AUD. A systematic review was conducted using PubMed, Cochrane, Web of Science, CINAHL, and Alcohol Studies Database to identify relevant peer-reviewed randomized controlled trials (RCTs) published between January 1990 and August 2016. Seven published trials have evaluated the impact of naltrexone on drinking outcomes in women distinct from men; 903 alcohol-dependent or heavy drinking women were randomized to receive once daily oral or depot (injectable) naltrexone or placebo with/without behavioral intervention. Two studies examining the quantity of drinks per day observed trends toward reduction in drinking quantity among women who received naltrexone versus placebo. The 4 studies examining the frequency of drinking had mixed results, with 1 study showing a trend that favored naltrexone, 2 showing a trend that favored placebo, and 1 that showed no difference. Two of the 3 studies examining time to relapse observed trends that tended to favor naltrexone for time to any drinking and time to heavy drinking among women who received naltrexone versus placebo. While the growing body of evidence suggests a variety of approaches to treat AUD, the impact of naltrexone to combat AUD in women is understudied. Taken together, the results suggest that naltrexone may lead to modest reductions in quantity of drinking and time to relapse, but not on the frequency of drinking in women. Future research should incorporate sophisticated study designs that examine gender differences and treatment effectiveness among those diagnosed with an AUD and present data separately for men and women.

Posttraumatic Stress Disorder and Alcohol Use Disorder: A Critical Review of Pharmacologic Treatments

Treatment of alcohol use disorder (AUD) is complicated by the presence of psychiatric comorbidity including posttraumatic stress disorder (PTSD). This is a critical review of the literature to date on pharmacotherapy treatments of AUD and PTSD. A systematic literature search using PubMed MESH terms for alcohol and substance use disorders, PTSD, and treatment was undertaken to identify relevant randomized controlled trials (RCTs). The studies were independently evaluated (ILP and TLS) and those that evaluated the efficacy of a pharmacotherapy for individuals diagnosed with AUD and PTSD and were RCTs were selected. Studies were grouped in 3 categories: (i) those that evaluated first-line treatments for PTSD, (ii) those that evaluated medications to target AUD, and (iii) those that evaluated medications hypothesized to be effective in targeting alcohol consumption as well as PTSD symptoms. Nine RCTs were identified; 3 focused on medications to treat PTSD, 4 focused on AUD, and 3 to target both. One study included both a medication to treat PTSD and 1 to treat AUD so was discussed twice. All but 1 of the studies found that PTSD symptoms and drinking outcomes improved significantly over time. There is not 1 agent with clear evidence of efficacy in this comorbid group. The results for medications to treat PTSD are inconclusive because of contradictory results. There was weak evidence to support the use of medications to treat AUD among those with comorbidity with PTSD. Findings for medications that were hypothesized to treat both disorders were also contradictory. Most studies provided a combination of interventions to treat both disorders. Despite the contradictory results, this review suggests that individuals with AUD and comorbid PTSD can safely be prescribed medications used in noncomorbid populations and patients improve with treatment.

Primary Care Providers' Interest in Using a Genetic Test to Guide Alcohol Use Disorder Treatment

BACKGROUND

Efforts to identify genetic moderators of pharmacotherapy response have generated interest in clinical applications of pharmacogenetic tests in alcohol use disorder (AUD) treatment. To date, no research on providers' interest in using pharmacogenetic tests in the context of AUD treatment has been reported. We conducted qualitative interviews with primary care providers from 5 clinics in the Veterans Health Administration (VA) to assess their interest in using a hypothetical genetic test to inform treatment of AUD with pharmacotherapy.

METHODS

Key contacts were used to recruit 24 providers from 5 primary care clinics associated with a single large VA medical facility. Participants completed 30-minute in-person semi-structured interviews focused on barriers and facilitators to provision of pharmacotherapy for AUD. Interviews included a hypothetical scenario regarding the availability of a genetic test to inform AUD pharmacotherapy provision and/or selection. Provider responses to the hypothetical scenario were recorded, transcribed and analyzed qualitatively using inductive content analysis. Data were independently coded by three investigators, and themes were identified via consensus.

RESULTS

Participants were generally interested in a genetic test to aid in AUD treatment planning. Five common themes were identified, including: perceived benefits of a pharmacogenetic test (e.g., aiding with therapeutic choice, positively impacting patient motivation for and engagement with AUD treatment), perceived drawbacks (e.g., limiting potential benefits of pharmacotherapy by reducing the target population for its receipt, adverse impacts of "negative" results), caveats to clinical utility (e.g., utility would depend on prognostic accuracy and/or medication characteristics), uncertainty as to whether such a test would impact clinical decision-making, and pragmatic barriers to use (costs and other resources, such as laboratory facilities).

CONCLUSIONS

Primary care providers in this study generally believed a genetic test to aid in AUD treatment planning would be useful, due to its potential to hone treatment choice as well as to influence patient motivation and adherence to treatment. However, providers acknowledged that a test's utility would depend on the strength of its prognostic characteristics, its other benefits relative to standard care, and lack of pragmatic barriers.

Reductions in Alcohol Craving Following Naltrexone Treatment for Heavy Drinking

AIMS

The role of craving for alcohol as a response to alcohol treatment is not well understood. We examined daily diary ratings of craving over the course of 28 days among individuals participating in an inpatient substance abuse treatment program.

METHODS

Participants were alcohol dependent patients (n = 100) in the Hazelden residential treatment program who were offered and agreed to take naltrexone and an age- and gender-matched comparison group (n = 100) of alcohol-dependent patients in the same program who declined the offer of treatment with naltrexone. Changes in craving over time were compared between the two groups.

RESULTS

The naltrexone-treated group reported a more rapid decrease in craving than the usual care group.

CONCLUSIONS

The change in the trajectory of craving is consistent with prior reports suggesting that craving reduction is a mechanism of naltrexone's efficacy in treating alcohol dependence. Providing naltrexone to individuals seeking treatment for alcohol dependence may accelerate a reduction in their craving, consistent with a primary target of many addiction treatment programs.

SHORT SUMMARY

Craving ratings by 100 residential patients taking naltrexone for alcohol dependence were compared to ratings by 100 patients who did not take naltrexone. Craving for alcohol decreased more rapidly in the patients taking naltrexone. Providing naltrexone to individuals seeking treatment for alcohol dependence may accelerate a reduction in craving, which may benefit treatment efforts.

Discovery, Development, and Adoption of Medications to Treat Alcohol Use Disorder: Goals for the Phases of Medications Development

For more than 25 years, advances have been made in developing medications to treat alcohol use disorder (AUD), highlighted by the U.S. Food and Drug Administration's approval of naltrexone (oral and long-acting) and acamprosate. Despite this progress, more work remains to be done in this area because these medications, although effective for some people, do not work for everyone. A high priority for the National Institute on Alcohol Abuse and Alcohol is to put into place a solid infrastructure to aid in the development of medications that are more effective than those currently available and with few side effects. Medication development, especially for a disorder as complex as AUD, is challenging and involves multiple phases, including discovery of "druggable" targets, preclinical studies, human clinical trials, and the adoption and implementation of the new medication into mainstream medicine. A successful medications development program requires clearly established goals for each phase to ensure that a candidate compound is not trapped in one particular phase, a condition known as "the valley of death." In this article, the phases of medication development are described as they apply to AUD, and specific goals of each phase are identified for the next decade. In addition, several important crosscutting themes are outlined for each phase, all of which are essential for advancing medications development. These include identifying and validating screening models and druggable targets, making use of precision medicine, and establishing partnerships among key stakeholders. Our goal in writing this article is to provide a guide on medications development that will aid the alcohol research community in planning, testing, and developing medications for AUD.

A gene-by-sex interaction for nicotine reward: evidence from humanized mice and epidemiology

It has been proposed that vulnerability to nicotine addiction is moderated by variation at the μ-opioid receptor locus (OPRM1), but results from human studies vary and prospective studies based on genotype are lacking. We have developed a humanized mouse model of the most common functional OPRM1 polymorphism rs1799971_A>G (A118G). Here we use this model system together with a cohort of German youth to examine the role of the OPRM1 A118G variation on nicotine reward. Nicotine reinforcement was examined in the humanized mouse model using i.v. self-administration. Male (n=17) and female (n=26) mice homozygous either for the major human A allele (AA) or the minor G allele (GG) underwent eight daily 2 h sessions of nicotine self-administration. Furthermore, male (n=104) and female (n=118) subjects homozygous for the A allele or carrying the G allele from the Mannheim Study of Children at Risk were evaluated for pleasurable and unpleasant experiences during their initial smoking experience. A significant sex-by-genotype effect was observed for nicotine self-administration. Male 118GG mice demonstrated higher nicotine intake than male 118AA mice, suggesting increased nicotine reinforcement. In contrast, there was no genotype effect in female mice. Human male G allele carriers reported increased pleasurable effects from their first smoking experience, as compared to male homozygous A, female G and female homozygous A allele carriers. The 118G allele appears to confer greater sensitivity to nicotine reinforcement in males, but not females.

Social network moderators of naltrexone and behavioral treatment effects on heavy drinking in the COMBINE study

BACKGROUND

Oral naltrexone is an efficacious medication for treatment of alcohol dependence, but small effect sizes and variability in outcomes suggest the presence of person-level moderators of naltrexone response. Identification of contextual or psychosocial moderators may assist in guiding clinical recommendations. Given the established importance of social networks in drinking outcomes, as well as the potential effects of naltrexone in reducing cue reactivity which may be especially important among those with more heavy drinkers and more alcohol cues in their networks, we examined pretreatment social network variables as potential moderators of naltrexone treatment effects in the COMBINE study.

METHODS

The sample included all COMBINE study participants in medication conditions with full data on the Important People Inventory (IPI) and covariates at intake (N = 1,197). The intake IPI assessed whether participants had any frequent drinkers in their network and the average frequency of contact with these drinkers. The effects of treatment condition, pretreatment network variables, and their interactions on percent heavy drinking days were tested in hierarchical linear models, controlling for demographics and baseline clinical covariates.

RESULTS

In treatment conditions involving medical management and combined behavioral intervention (CBI), the effects of active naltrexone on heavy drinking were significantly greater for individuals with frequent drinkers in their network (z = -2.66, p < 0.01) and greater frequency of contact with those drinkers (z = -3.19, p < 0.01). These network variables did not moderate the effects of active naltrexone without CBI.

CONCLUSIONS

When delivered in conjunction with behavioral interventions, naltrexone can be more potent for alcohol-dependent adults who have greater contact with frequent drinkers prior to treatment, which may indicate patterns of environmental exposure to alcohol. Contextual, social risk factors are a potential avenue to guide personalized treatment of alcohol dependence.

Evaluation of N-substituent structural variations in opioid receptor profile of LP1

The benzomorphan scaffold has great potential as lead structure and the nature of the N-substituent is able to influence affinity, potency, and efficacy at all three opioid receptors. Building upon these considerations, we synthesized a new series of LP1 analogues by introducing naphthyl or heteroaromatic rings in propanamide side chain of its N-substituent (9-15). In vitro competition-binding assays in HEK293 cells stably expressing MOR, DOR or KOR showed that in compound 9 the 1-naphthyl ring led to the retention of MOR affinity (Ki(MOR)=38±4nM) displaying good selectivity versus DOR and KOR. In the electrically stimulated GPI, compound 9 was inactive as agonist but produced an antagonist potency value (pA2) of 8.6 in presence of MOR agonist DAMGO. Moreover, subcutaneously administered it antagonized the antinociceptive effects of morphine with an AD50=2.0mg/kg in mouse-tail flick test. Modeling studies on MOR revealed that compound 9 fit very well in the binding pocket but in a different way in respect to the agonist LP1. Probably the replacement of its N-substituent on the III, IV and V TM domains reflects an antagonist behavior. Therefore, compound 9 could represent a potential lead to further develop antagonists as valid therapeutic agents and useful pharmacological tools to study opioid receptor function.

Prairie Voles as a Model to Screen Medications for the Treatment of Alcoholism and Addictions

Most preclinical studies of medications to treat addictions are performed in mice and rats. These two rodent species belong to one phylogenetic subfamily, which narrows the likelihood of identifying potential mechanisms regulating addictions in other species, ie, humans. Expanding the genetic diversity of organisms modeling alcohol and drug abuse enhances our ability to screen for medications to treat addiction. Recently, research laboratories adapted the prairie vole model to study mechanisms of alcohol and drugs of abuse. This development not only expanded the diversity of genotypes used to screen medications, but also enhanced capabilities of such screens. Prairie voles belong to 3-5% of mammalian species exhibiting social monogamy. This unusual trait is reflected in their ability to form lasting long-term affiliations between adult individuals. The prairie vole animal model has high predictive validity for mechanisms regulating human social behaviors. In addition, these animals exhibit high alcohol intake and preference. In laboratory settings, prairie voles are used to model social influences on drug reward and alcohol consumption as well as effects of addictive substances on social bonding. As a result, this species can be adapted to screen medications whose effectiveness could be (a) resistant to social influences promoting excessive drug taking, (b) dependent on the presence of social support, and (c) medications affecting harmful social consequences of alcohol and drug abuse. This report reviews the literature on studies of alcohol and psychostimulants in prairie voles and discusses capabilities of this animal model as a screen for novel medications to treat alcoholism and addictions.

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.

The Need for Treatment Responsive Translational Biomarkers in Alcoholism Research

Over the past two decades, major advances have been made in the basic neuroscience of alcohol addiction. However, few of these have been translated into clinically useful treatments, which remain limited. In the past decade, psychiatric drug development in general has been stalled, with many preclinically validated mechanisms failing in clinical development. Despite the existence of appealing preclinical models in the area of addictive disorders, drug development for these conditions has been impacted by the exodus of major pharma from psychiatric neuroscience. Here, we discuss translational biomarker strategies that may help turn this tide. Following an approach patterned on an endophenotype approach to complex behavioral traits, we hypothesize that relatively simple biological measures should be sought that can be obtained both in experimental animals and in humans, and that may be responsive to alcoholism medications. These biomarkers have to be tailored to the specific mechanism targeted by candidate medications and may in fact also help identify biologically more homogeneous subpopulations of patients. We introduce as examples alcohol-induced dopamine (DA) release, measures of central glutamate levels, and network connectivity, and discuss our experience to date with these biomarker strategies.