Naltrexone's Effect on Cue-Elicited Craving Among Alcoholics in Treatment

Testing pharmacotherapies for alcohol use disorder with cue exposure paradigms: A systematic review and quantitative synthesis of human laboratory trial methodology

Alcohol cue exposure is a widely used experimental paradigm for screening pharmacotherapies for alcohol use disorder (AUD). Medication-related reductions in cue-reactivity signal early efficacy and inform medications development. Yet, across trials, the design of cue exposure, parameter testing, and outcome reporting is heterogeneous. This systematic review is a quantitative synthesis of trial methodologies and effect size estimation for AUD medication-related craving and psychophysiological outcomes under the cue exposure paradigm. A PubMed search was conducted on January 3, 2022 based on identified pharmacotherapies for peer-reviewed articles reported in English. Study-level characteristics, including sample descriptors, paradigm design, analytic approach, and Cochrane Risk of Bias, along with descriptive statistics for cue-exposure outcomes, were coded by two independent raters. Study-level effect sizes were estimated for craving and psychophysiological outcomes separately and sample-level effect sizes were calculated for each medication. Thirty-six trials, comprising 1640 participants and testing 19 different medications satisfied eligibility criteria. All studies reported on biological sex (71% male participants on average). The exposure paradigms implemented used in vivo (n = 26), visual (n = 8), and audio script (n = 2) cues. Some trials included means for craving by medication condition in text (k = 7) or figures (k = 18). The quantitative synthesis included 63 effect sizes (craving kes  = 47; psychophysiological kes  = 16) from 28 unique randomized trials testing 15 medications for effects on cue reactivity. For cue-induced craving, eight medications (kes range: 1-12) demonstrated small-to-medium effects (Cohen's d range: |0.24-0.64|) compared to placebo, with individuals randomized to receive medication reporting lower craving following cue exposure. Recommendations are provided to promote further consilience, so that the utility of cue exposure paradigms can be maximized in the development of effective AUD pharmacotherapies. Future work should explore the predictive utility of medication-related reductions in cue-reactivity on clinical outcomes.

Effects of Alcohol Cue Reactivity on Subsequent Treatment Outcomes Among Treatment-Seeking Individuals with Alcohol Use Disorder: A Multisite Randomized, Double-Blind, Placebo-Controlled Clinical Trial of Varenicline

BACKGROUND

The alcohol cue reactivity paradigm is increasingly used to screen medications for the treatment of alcohol use disorder (AUD) and other substance use disorders. Yet, its prospective association with craving and naturalistic drinking outcomes in clinical trials remains unknown. This study embedded repeated human laboratory assessments of alcohol cue reactivity within the context of a randomized controlled trial to examine the effects of varenicline tartrate (Chantix® ), a partial agonist of α4β2 nicotinic acetylcholine receptors, on alcohol craving among treatment-seeking heavy drinkers with AUD. Our main objectives were to test whether varenicline, as compared to placebo, blunts alcohol cue-elicited craving and test whether alcohol cue reactivity observed in the human laboratory predicts subsequent alcohol craving and use during the remainder of the trial.

DESIGN AND METHODS

This double-blind, randomized, 2-site study compared the effects of varenicline (up to 2 mg/d) and placebo on responses to in vivo alcohol cue and affective picture cue exposure in the human laboratory. Forty-seven volunteers (18 females, 29 males), ages 23 to 67 years (M = 43.7, SD = 11.5), were recruited from the community via advertisements to participate in a clinical trial designed to study the effects of varenicline on alcohol use. Participants were randomized to either varenicline or placebo for 6 weeks.

RESULTS

Varenicline did not attenuate cue-induced alcohol craving relative to placebo, but craving captured during the cue reactivity paradigm significantly predicted subsequent alcohol use in real-world settings during the clinical trial. Higher craving predicted heavier alcohol use.

CONCLUSIONS

Our results are among the first to show alcohol cue-induced craving captured during a human laboratory paradigm predicts drinking outcomes in the context of a clinical trial.

Examining the Relationship Between Self-Reported Drinking and In-Laboratory Drinking and Craving: Is There Concordance?

BACKGROUND

In-laboratory drinking sessions that allow direct assessment of drinking and craving are an emerging method for testing novel pharmacotherapy compounds and behavioral interventions for alcohol use disorders. Despite wide implementation, limited evidence supports the concordance between drinking in the laboratory and in a natural setting. This study examined the relationship between self-reports of drinking prior to and drinking and craving during an alcohol drinking paradigm (ADP).

METHODS

Participants were adult heavy drinkers (N = 64) who participated in a pharmacotherapy study. Participants completed self-report alcohol assessments and a baseline ADP session prior to any medication administration. Alcohol craving was assessed during priming and ad lib ADP phases. Outcomes were the associations of total drinks consumed in-laboratory and summary drinking measures for the 30 days prior to the ADP and reports of maximum drinks (past year and lifetime). Additional outcomes were the association of self-reported drinking and alcohol craving during the ADP and the concordance between self-report and ADP World Health Organization (WHO) drinking classifications.

RESULTS

Number of drinking days, average drinks per drinking occasion, and lifetime and past-year maximum drinks were all related to drinking in the laboratory. Heavy drinking days were not related to drinking in the laboratory but were associated with ADP craving. Alcohol craving was also associated with other measures of self-reported drinking. There was also a significant association between WHO drinking risk classification and in-laboratory drinking.

CONCLUSIONS

The observed relationships between self-reported drinking and drinking in-laboratory across drinking indices suggest that in-laboratory alcohol consumption may reflect participants' real-world alcohol consumption, supporting the value of laboratory-based drinking paradigms. The demonstrated relationship with self-reported drinking and ADP alcohol craving further supports the value of such paradigms to model key drinking predictors. These results provide support for the validity of laboratory-based paradigms to accurately reflect participants' recent drinking levels.

Serum Insulin Levels Are Reduced by Intravenous Ghrelin Administration but Do Not Correlate with Alcohol Craving in Alcohol-Dependent Individuals

BACKGROUND

Increasing evidence supports a role for appetite-regulating pathways like ghrelin, insulin, and leptin in alcoholism. We previously reported that intravenous (i.v.) exogenous ghrelin increases alcohol craving. We also reported i.v. ghrelin reduces endogenous serum leptin, whose levels, in turn, negatively correlated with alcohol craving. Exogenous ghrelin administration decreases insulin secretion both in vitro and in vivo experiments. This study tested the hypothesis that i.v. ghrelin may also decrease endogenous serum insulin levels in alcoholic individuals. Additionally, we explored possible correlations between serum insulin and alcohol craving, since a correlation between insulin and alcohol craving was previously reported.

METHODS

This was a double-blind, placebo-controlled human laboratory study ( n =43). Non-treatment-seeking, alcohol-dependent, heavy drinkers were randomized to receive i.v. ghrelin or placebo, followed by an alcohol cue-reactivity procedure.

RESULTS

There was a main effect for i.v. ghrelin, compared to placebo in reducing serum insulin ( P <.05). There was also a time effect ( P <.001) but not ghrelin x time interaction ( P >.05). We did not find a correlation between the reduction of serum insulin and alcohol craving ( P >.05). The change in serum insulin was consistent with a parallel reduction in serum connective-peptide in the ghrelin group compared with placebo, although this difference did not reach statistical significance ( P =.076). No similar effects were found for other glucose-regulating hormones analyzed i.e. glucagon, glucagon-like peptide-1, and gastric inhibitory peptide ( P s>.05).

CONCLUSIONS

These findings indicate i.v. ghrelin administration has an effect on reducing serum insulin in alcohol-dependent individuals; however, the reduction of insulin did not correlate with changes in alcohol cue-elicited craving. We speculate that, unlike for leptin, the interactions between ghrelin and insulin relationship are limited at the peripheral level. However, mechanistic studies are needed to investigate this hypothesis.

Cravings as a mediator and moderator of drinking outcomes in the COMBINE study

AIMS

Investigators of the COMBINE (Combining Medications and Behavioral Interventions for Alcoholism) study examined whether combining medications with a behavioral intervention would improve outcomes over monotherapies. Unexpectedly, the combination did not offer any advantage over either treatment alone. This study aimed to explain the lack of incremental benefit offered by the combination over either monotherapy by assessing the role of cravings as a treatment mediator and moderator.

DESIGN

Secondary mediation and moderation analyses of COMBINE study data.

SETTING

Eleven United States academic sites.

PARTICIPANTS

A total of 863 patients randomized to one of four treatment groups: naltrexone (100 mg/day; n = 209), the combined behavioral intervention (CBI, n = 236), naltrexone and CBI combined (n = 213) and placebo naltrexone (n = 205).

MEASUREMENTS

Percentage of days abstinent (PDA) measured between 13 and 16 weeks post-baseline. Cravings, the potential mediator/moderator, were measured at baseline, weeks 4 and 12 using the Obsessive-Compulsive Drinking Scale.

FINDINGS

Compared with placebo, naltrexone, CBI and the combination all increased PDA by an additional 6-10 percentage points for those with high cravings (P < 0.05 for all three treatment groups). None had significant effects on PDA for those with low cravings. The effects of all three treatments were mediated at least partially by cravings; craving reduction explained 48-53% of treatment effects (P < 0.05 for all three treatment groups). Furthermore, naltrexone appeared to reduce cravings at 4 weeks, while CBI did not reduce cravings until 12 weeks.

CONCLUSIONS

The Combining Medications and Behavioral Interventions for Alcoholism (COMBINE) naltrexone + CBI combination may not be more beneficial than either monotherapy because craving reduction is a common mechanism of both.

Does naltrexone affect craving in abstinent opioid-dependent patients?

Naltrexone blocks the opioid receptors that modulate the release of dopamine in the brain reward system and therefore blocks the rewarding effects of heroin and alcohol. It is generally assumed that naltrexone leads to reduction of craving, but few studies have been performed to prove this. The purpose of the present study was to examine the effect of the administration of naltrexone on craving level after rapid opioid detoxification induced by naltrexone. A naturalistic study was carried out in which patients were followed during 10 months after rapid detoxification. Data about abstinence, relapse, and naltrexone use were collected by means of urine specimens. Craving was measured by the visual analogue scale craving, the Obsessive Compulsive Drug Use Scale, and the Desires for Drug Questionnaire. Results showed that patients who relapsed in opioid use experienced obviously more craving than abstinent people. Patients who took naltrexone did not experience significant less craving than those who did not. These results suggest that the use of opioids is associated with increased craving and that abstinence for opioids is associated with less craving, independent of the use of naltrexone. This is in contrast to the general opinion. Because of the naturalistic design of the study, no firm conclusions can be drawn, but the results grounded the needs of an experimental study.

Preclinical and clinical pharmacology of alcohol dependence

In recent years, advances in neuroscience led to the development of new medications to treat alcohol dependence and especially to prevent alcohol relapse after detoxification. Whereas the earliest medications against alcohol dependence were fortuitously discovered, recently developed drugs are increasingly based on alcohol's neurobiological mechanisms of action. This review discusses the most recent developments in alcohol pharmacotherapy and emphasizes the neurobiological basis of anti-alcohol medications. There are currently three approved drugs for the treatment of alcohol dependence with quite different mechanisms of action. Disulfiram is an inhibitor of the enzyme aldehyde dehydrogenase and acts as an alcohol-deterrent drug. Naltrexone, an opiate antagonist, reduces alcohol craving and relapse in heavy drinking, probably via a modulation of the mesolimbic dopamine activity. Finally, acamprosate helps maintaining alcohol abstinence, probably through a normalization of the chronic alcohol-induced hyperglutamatergic state. In addition to these approved medications, many other drugs have been suggested for preventing alcohol consumption on the basis of preclinical studies. Some of these drugs remain promising, whereas others have produced disappointing results in preliminary clinical studies. These new drugs in the field of alcohol pharmacotherapy are also discussed, together with their mechanisms of action.

Genetic moderators of naltrexone's effects on alcohol cue reactivity

BACKGROUND

Naltrexone (NTX) reduces drinking and craving in alcoholic individuals in treatment and also in heavy drinkers. Polymorphisms in the D4 dopamine receptor (DRD4) gene and mu-opiate receptor gene (OPRM1) may moderate NTX's effects on craving. This study examined these candidate genes as moderators of the effects of NTX on cue-elicited urge to drink in non-treatment-seeking heavy drinkers.

METHOD

Data from the subset of 93 participants who consented for genetic testing in a larger study of medication effects were used to examine pharmacogenetic hypotheses. The non-treatment-seeking male and female heavy drinkers (62% alcohol dependent) were genotyped for the variable number of tandem repeats polymorphism in the DRD4 gene [L=7 or more (n=34), S=less than 7 (n=56)] and Asn40Asp single-nucleotide polymorphism in the OPRM1 gene [29 aspartate (Asp) carriers and 59 asparagine (Asn) homozygotes]. Ten days after randomization to NTX (50 mg) or placebo, participants completed an alcohol cue reactivity assessment.

RESULTS

Any medication effects were all accounted for by interaction with genotype. Naltrexone increased urge for alcohol in Asp carriers across alcohol and neutral beverage cue trials and had no effect on homozygous Asn carriers. Asp40 carriers on either medication had greater decreases (from resting baseline) in mean arterial blood pressure across all beverage cue trials compared with Asn carriers. For DRD4, no differential medication effects by DRD4 polymorphism were found. Alcohol dependence diagnosis did not moderate the effects of gene and medication on cue-elicited measures.

DISCUSSION

The differential responses to NTX due to variation in the OPRM1 gene may help explain conflicting results in clinical trials and suggest directions for patient-treatment matching.

Genetically selected Marchigian Sardinian alcohol-preferring (msP) rats: an animal model to study the neurobiology of alcoholism

The present article provides an up-to-date review summarizing almost 18 years of research in genetically selected Marchigian Sardinian alcohol-preferring (msP) rats. The results of this work demonstrate that msP rats have natural preference for ethanol characterized by a spontaneous binge-type of drinking that leads to pharmacologically significant blood ethanol levels. This rat line is highly vulnerable to relapse and presentation of stimuli predictive of alcohol availability or foot-shock stress can reinstate extinguished drug-seeking up to 8 months from the last alcohol experience. The msP rat is highly sensitive to stress, shows an anxious phenotype and has depressive-like symptoms that recover following ethanol drinking. Interestingly, these animals have an up-regulated corticotrophin releasing factor (CRF) receptor 1 system. Clinical studies have shown that alcoholic patients often drink ethanol in the attempt to self-medicate from negative affective states and to search for anxiety relief. We propose that msP rats represent an animal model that largely mimics the human alcoholic population that due to poor ability to engage in stress-coping strategies drink ethanol as a tension relief strategy and for self-medication purposes.

The effects of naltrexone on alcohol consumption and affect reactivity to daily interpersonal events among heavy drinkers

The authors examined whether the associations among daily positive and negative interpersonal events, alcohol consumption, and affect varied as a function of naltrexone or placebo administered in a targeted (in anticipation of or in response to high-risk drinking situations) or daily fashion. Heavy drinkers (N = 149) received 4 sessions of brief coping skills counseling in addition to 8 weeks of naltrexone treatment. They recorded for 8 weeks in structured nightly diaries their interpersonal interactions, affect, and alcohol consumption. The authors predicted that participants receiving naltrexone, compared with those taking placebo, would drink less in response to interpersonal encounters and that naltrexone administration would attenuate the link between positive interpersonal events and positive affective states. Results indicated that both positive and negative interpersonal interactions were associated with an increased probability of engaging in any drinking and that positive daily social celebratory events were associated with an increased probability of engaging in heavy drinking. Participants taking naltrexone in a targeted fashion showed the strongest positive association between the number of positive social celebratory events and drinking. Although this finding was inconsistent with the overall reduction in drinking that has been generally reported for those treated with naltrexone, positive social celebratory events occurred on only a minority of days. Participants taking naltrexone, compared with those taking placebo, showed weaker associations between positive social celebratory events and positive and negative affective states. Findings are discussed in terms of naltrexone's dampening effects on the rewarding properties of alcohol use and certain positively valenced stimuli.

Reward craving and withdrawal relief craving: assessment of different motivational pathways to alcohol intake

AIMS

Craving for the rewarding effects of alcohol may be evoked by conditioned alcohol-like effects whereas conditioned compensatory responses may induce withdrawal relief craving. We tested the hypothesis that drinking in positive emotional states is associated with appetitive reactions to alcohol-associated cues and contributes to reward craving, while conditioned withdrawal is associated with drinking in negative situations and distressful, obsessive preoccupations with alcohol.

METHODS

In 38 detoxified alcoholics, the Obsessive Compulsive Drinking Scale was used to assess the craving factors 'impaired control', 'interference with social functioning' and 'obsession'. Affective responses to alcohol-associated visual stimuli were measured with the affect-modulated eyeblink startle reflex, positive and negative drinking situations with the Inventory of Drinking Situations (IDS) and withdrawal-like symptoms preceding alcohol intake with the revised Clinical Institute Assessment for Alcohol Scale (CIWA-Ar).

RESULTS

Appetitive reactions to alcohol-associated cues correlated positively with drinking in positive situations and contributed significantly to the craving factor 'interference' with social and work functioning. The severity of withdrawal-like symptoms preceding alcohol intake contributed to the craving factor 'obsession'; however, contrary to our hypothesis, this measure of conditioned withdrawal correlated with drinking not only in negative but also in positive situations.

CONCLUSIONS

Drinking in positive and negative situations, appetitive reactions to alcohol and withdrawal-like symptoms contributed differentially to the craving factors 'obsession' and 'interference', supporting the notion of different craving factors with separate underlying mechanisms.

Coping and social skills training for alcohol and cocaine dependence

Coping and Social Skills Training (CSST) has been in the forefront of the addictions literature for over two decades. In this review, we provide an outline of empirically validated CSST assessment measures and treatment protocols for alcohol dependence and cocaine dependence. Key elements covered in CSST include communication skills training, cue exposure treatment with urge coping skills, and cocaine-specific coping skills training. We conclude with a summary of the research to date in support of CSSt and future directions for the treatment of addictive behaviors.