Defining the role of baclofen for the treatment of alcohol dependence: a systematic review of the evidence

Prolonged Exposure to Cocaine Self-Administration Results in a Continued Progression of Alterations in Functional Activity in a Nonhuman Primate Model

Background

Studies of nonhuman primates with exposures of up to 100 days of cocaine self-administration (SA) have provided evidence that the central effects of cocaine progress over time. These durations of cocaine exposure, however, may be insufficient to capture the extent of the neurobiological alterations observed in cocaine users, many of whom use the drug for years. The goal of the present study was to determine whether 1.5 years of cocaine SA would result in further progression of alterations in functional brain activity.

Methods

Adult male rhesus monkeys were exposed to 300 sessions of high-dose cocaine SA over 1.5 years. Following the final session rates of local cerebral glucose utilization (LCGU) were assessed with the 2-[¹⁴C]-deoxyglucose method and compared to rates of LCGU in control monkeys who responded for food reinforcement. In addition, LCGU in these animals was compared to a previously published group of monkeys that had self-administered cocaine or food for 100 sessions over a 4-5 month period.

Results

Compared to 100 days of exposure, 300 days of cocaine SA further reduced LCGU in the post-commissural striatum and produced reductions in areas unaffected by the shorter duration of exposure, such as the hypothalamus, all of the amygdala, and large expanses of cortex.

Conclusions

These findings demonstrate a clear progression of the impact of cocaine on functional activity with increasing durations of drug experience and have important implications for the development of potential strategies for the treatment of cocaine use disorder.

GABAB receptors in prelimbic cortex and basolateral amygdala differentially influence intertemporal decision making and decline with age

The ability to decide adaptively between immediate vs. delayed gratification (intertemporal choice) is critical for well-being and is associated with a range of factors that influence quality of life. In contrast to young adults, many older adults show enhanced preference for delayed gratification; however, the neural mechanisms underlying this age difference in intertemporal choice are largely un-studied. Changes in signaling through GABA_B receptors (GABA_BRs) mediate several age-associated differences in cognitive processes linked to intertemporal choice. The current study used a rat model to determine how GABA_BRs in two brain regions known to regulate intertemporal choice (prelimbic cortex; PrL and basolateral amygdala; BLA) contribute to age differences in this form of decision making in male rats. As in humans, aged rats showed enhanced preference for large, delayed over small, immediate rewards during performance in an intertemporal choice task in operant test chambers. Activation of PrL GABA_BRs via microinfusion of the agonist baclofen increased choice of large, delayed rewards in young adult rats but did not influence choice in aged rats. Conversely, infusion of baclofen into the BLA strongly reduced choice of large, delayed rewards in both young adult and aged rats. Aged rats further showed a significant reduction in expression of GABA_BR1 subunit isoforms in the prefrontal cortex, a discovery that is consonant with the null effect of intra-PrL baclofen on intertemporal choice in aged rats. In contrast, expression of GABA_BR subunits was generally conserved with age in the BLA. Jointly, these findings elucidate a role for GABA_BRs in intertemporal choice and identify fundamental features of brain maturation and aging that mediate an improved ability to delay gratification.

Evaluation of spin in the abstracts of systematic reviews and meta-analyses focused on treatments of alcohol use disorder

Background: With 14.4 million U.S. adults diagnosed with alcohol use disorder (AUD) annually, effective treatments for combatting this condition are essential. Clinicians are often guided by systematic reviews and meta-analyses - considered the gold standard of research. Spin, a biased way of reporting results, may lead to misinterpretation of research findings, resulting in suboptimal patient care.Objective: Our primary objective was to investigate the presence of spin in the abstracts of systematic reviews of AUD treatments.Methods: After systematically searching MEDLINE and Embase for systematic reviews of AUD treatments, abstracts were evaluated for the nine most severe types of spin. Additional article characteristics were concurrently extracted and study quality was evaluated. Descriptive statistics of spin were calculated and associations between spin and study characteristics were determined through Fisher's exact and logistic regression.Results: Among 79 included systematic reviews, 44 instances of spin were identified spanning 43% of our sample (34/79). Of the nine forms of spin, eight were found with a majority of instances being "selective reporting of or overemphasis on efficacy outcomes" (13/44, 29.5% of cases). The majority of articles were rated as critically low quality (51/79, 64.6%). No association was found between the presence of spin and extracted study characteristics.Conclusions: Spin was found in more than 40% of systematic review abstracts that evaluated pharmacotherapies in the treatment of AUD. Coupled with the finding that the majority of systematic reviews on the subject were of low quality, increased awareness of spin among physicians may be warranted.

The influence of anxiety symptoms on clinical outcomes during baclofen treatment of alcohol use disorder: A systematic review and meta-analysis

Given the high coexistence of anxiety symptoms in people with alcohol use disorder (AUD), we aimed to determine the influence of anxiety symptoms on outcomes in patients with AUD treated with the GABA_B receptor agonist baclofen. A meta-analysis of 13 comparisons (published 2010-2020) including baseline and outcome data on alcohol consumption and anxiety after 12 weeks was undertaken. There were significantly higher rates of abstinent days in patients treated with baclofen compared to placebo (p = 0.004; high certainty evidence); specifically in those with higher baseline anxiety levels (p < 0.00001; high certainty evidence) compared to those with lower baseline anxiety levels (p = 0.20; moderate certainty evidence). The change in anxiety ratings over 12 weeks did not differ between those treated with baclofen or placebo (p = 0.84; moderate certainty evidence). This may be due to different anxiety constructs being measured by scales not validated in this patient group, or that anxiety is not a biobehavioral mechanism by which baclofen may reduce alcohol drinking. Given the prevalence of anxiety symptoms in AUD all these factors warrant further research.

Baclofen: its effectiveness in reducing harmful drinking, craving, and negative mood. A meta-analysis

BACKGROUND AND AIMS

There are a limited number of pharmacotherapies licensed for alcohol use disorders (AUDs). Baclofen is a γ-aminobutyric acid B (GABA-B) agonist which is used increasingly as an off-label treatment. A meta-analysis of randomized controlled trials (RCTs) was conducted to determine the efficacy of baclofen in reducing drinking behaviour, craving, depression and anxiety compared with placebo.

METHODS

Random-effects meta-analyses were computed on outcome data from 12 RCTs comparing baclofen with placebo. Included RCTs provided data on at least one of the primary outcome measures (drinking-related: heavy drinking days, abstinent days, abstinence rates) or secondary outcome measures (craving, anxiety, depression).

RESULTS

Baclofen had a significant effect on abstinence rates when using intention-to-treat analysis [total n baclofen = 307, total n control = 283: odds ratio (OR) = 2.67, 95% confidence interval (CI) = 1.03, 6.93; Z = 2.01, P = 0.04, I²  = 76%, number needed to treat = 8]. No other significant effects of treatment efficacy [e.g. heavy drinking days: standardized mean differences (SMD) = -0.26, 95% CI = -0.68, 0.15; Z = 1.24, P = 0.21, I²  = 95%] or mechanism of action (e.g. craving: SMD = -0.13, 95% CI = -0.36, 0.09; Z = 1.18, P = 0.24, I²  = 87%) were observed. There was substantial heterogeneity in effect sizes across each analysis.

CONCLUSIONS

As a treatment for alcohol use disorders, baclofen is associated with higher rates of abstinence than placebo. However, there is no superior effect of baclofen on increasing number of abstinent days, or decreasing heavy drinking, craving, anxiety or depression. These results suggest that the current increasing use of baclofen as a treatment for alcohol use disorders is premature.

Analgesic effect of ADX71441, a positive allosteric modulator (PAM) of GABAB receptor in a rat model of bladder pain

Therapeutic use of GABA_B receptor agonists for conditions like chronic abdominal pain, overactive bladder (OAB) and gastroesophageal reflux disease (GERD) is severely affected by poor blood-brain barrier permeability and potential side effects. ADX71441 is a novel positive allosteric modulator (PAM) of the GABA_B receptor that has shown encouraging results in pre-clinical models of anxiety, pain, OAB and alcohol addiction. The present study investigates the analgesic effect of ADX71441 to noxious stimulation of the urinary bladder and colon in rats. In female Sprague-Dawley rats, systemic (i.p), but not intrathecal (i.t), administration of ADX71441 produced a dose-dependent decrease in viscero-motor response (VMR) to graded urinary bladder distension (UBD) and colorectal distension (CRD). Additionally, intra-cerebroventricular (i.c.v.) administration of ADX71441 significantly decreased the VMRs to noxious UBD. In electrophysiology experiments, the drug did not attenuate the responses of UBD-sensitive pelvic nerve afferent (PNA) fibers to UBD. In contrast, ADX71441 significantly decreased the responses of UBD-responsive lumbosacral (LS) spinal neurons in spinal intact rats. However, ADX71441 did not attenuate these LS neurons in cervical (C1-C2) spinal transected rats. During cystometrogram (CMG) recordings, ADX71441 (i.p.) significantly decreased the VMR to slow infusion without affecting the number of voiding contraction. These results indicate that ADX71441 modulate bladder nociception via its effect at the supra-spinal sites without affecting the normal bladder motility and micturition reflex in naïve adult rats.

Effects of acute administration of the GABA(B) receptor agonist baclofen on behavioral flexibility in rats

RATIONALE

The ability to adjust response strategies when faced with changes in the environment is critical for normal adaptive behavior. Such behavioral flexibility is compromised by experimental disruption of cortical GABAergic signaling, as well as in conditions such as schizophrenia and normal aging that are characterized by cortical hyperexcitability. The current studies were designed to determine whether stimulation of GABAergic signaling using the GABA(B) receptor agonist baclofen can facilitate behavioral flexibility.

METHODS

Male Fischer 344 rats were trained in a set-shifting task in which they learned to discriminate between two response levers to obtain a food reward. Correct levers were signaled in accordance with two distinct response rules (rule 1: correct lever signaled by a cue light; rule 2: correct lever signaled by its left/right position). The order of rule presentation varied, but they were always presented sequentially, with the trials and errors to reach criterion performance on the second (set shift) rule providing the measure of behavioral flexibility. Experiments determined the effects of the GABA(B) receptor agonist baclofen (intraperitoneal, 0, 1.0, 2.5, and 4.0 mg/kg) administered acutely before the shift to the second rule.

RESULTS

Baclofen enhanced set-shifting performance. Control experiments demonstrated that this enhancement was not simply due to improved discrimination learning, nor was it due to impaired recall of the initial discrimination rule.

CONCLUSIONS

The results demonstrate that baclofen can facilitate behavioral flexibility, suggesting that GABA(B) receptor agonists may have utility for treating behavioral dysfunction in neuropsychiatric disorders.

Alcohol-induced dysregulation of stress-related circuitry: The search for novel targets and implications for interventions across the sexes

While the ability to process fermented fruits and alcohols was once an adaptive trait that improved nutrition and quality of life, the availability and prevalence of high potency alcoholic drinks has contributed to alcohol abuse disorders in a vulnerable portion of the population. Although the neural reward systems take part in the initial response to alcohol, negative reinforcement and stress, which are normally adaptive responses, can intersect to promote continued alcohol use at all stages of the addiction cycle. Eventually a point is reached where these once adaptive responses become dysregulated resulting in uncontrolled intake that constitutes a clinically important condition termed alcohol use disorder (AUD). Current research is targeted at both the behavioral and molecular adaptations in AUDs in an effort to better develop novel approaches to intervention. In this review, historical context is provided demonstrating the societal burden of alcohol use and abuse disorders. The importance of gender in the mechanism of action of alcohol is discussed. Finally, the impact of alcohol on stress-related circuitry, uncovered by preclinical research, is outlined to provide insight into potential novel pharmacological approaches to the treatment of AUD.

Dexmedetomidine for acute baclofen withdrawal

BACKGROUND

Intrathecal baclofen is widely accepted as a treatment option for severe spasticity through its γ-Aminobutyric acid-B (GABAB ) agonist properties. Abrupt cessation can lead to severe and life-threatening withdrawal characterized by altered mental status, autonomic dysreflexia, rigidity, and seizures. This symptomatic presentation is similar to alcohol withdrawal, which is mediated by modification of GABAA expression. Use of the α2-adrenergic agonist dexmedetomidine for the treatment of ethanol withdrawal has been widely reported, raising the question of its potential role in baclofen withdrawal. We present a case of the successful treatment of acute severe baclofen withdrawal with a dexmedetomidine infusion.

METHODS

A 15-year-old patient with spastic quadriparesis and cerebral palsy underwent unexpected removal of his baclofen pump due to an infection that was encountered during a planned pump revision. Following removal, he was placed on high dose enteral baclofen every 6 h. Despite further benzodiazepine supplementation, he had progressive hemodynamic instability, severe rebound spasticity, and intermittent spontaneous clonus consistent with baclofen withdrawal. A dexmedetomidine infusion was titrated to a peak dose of 16 mcg per hour with successful treatment of withdrawal symptoms.

RESULTS

The patient became normotensive without tachycardia. Tone and agitation improved.

CONCLUSION

Dexmedetomidine is to our knowledge a previously unreported option for treatment of acute severe baclofen withdrawal. We report a case of safe and efficacious use in a patient with spastic quadriparesis on chronic intrathecal baclofen. Scientifically rigorous comparison with other options remains to be performed.

Correlates of Baclofen Effectiveness in Alcohol Dependence

Alcohol dependence is a global concern. Baclofen has shown promise as an anti-craving agent but its efficiency remains to be settled. We reviewed 549 male cases diagnosed with alcohol dependence who received Acamprosate (201) or Baclofen (348). 'Time to first drink' was compared between two groups and multiple regression analysis was done in baclofen group to identify correlates of effectiveness. There was a significant difference in outcome measure between Baclofen (M = 4.44, SD = 3.75) and Acamprosate group (M = 3.73, SD = 2.19); t (547) = 2.45, P = 0.01. Initial regression analysis with six predictor variables (average daily alcohol units, current age, age at onset of dependence, family history, duration of dependence and dose of baclofen in mg/day) showed significant correlation of outcome variable with only two predictor variables - dose of baclofen and average daily intake. Using the hierarchical method it was found that 'dose of baclofen' and 'average alcohol intake' explain a significant amount of variance in 'time to first drink'. [F (1, 345) = 182.8, P < 0.001, R2 = 0.52, R2adjusted = 0.51]. This information can be used to select patients in long term longitudinal studies and may explain variable results seen in clinical trials of baclofen done earlier.

Pharmacotherapy for alcohol addiction in a patient with alcoholic cirrhosis and massive upper gastrointestinal bleed: A case study

Alcohol use causes a substantial burden of morbidity and mortality worldwide. The pharmacologic treatment of alcohol dependence has been increasingly studied and proven to improve outcomes in individuals with alcohol use disorder. However, the treatment of alcohol use disorder is often challenging in the context of patients with hepatic impairment as many medications to treat alcohol use disorder are hepatically metabolised or may cause liver toxicity in some instances. We present a case history of an individual with significant medical complications from alcohol use disorder and explore the dilemma faced in prescribing pharmacologic treatment of alcohol use disorder in patients with significant liver dysfunction.

Systematic review of the pharmacological treatment of alcohol use disorders in individuals infected with hepatitis C

Treating alcohol use disorders (AUD) is critical in individuals suffering from hepatitis C infection (HCV). Aside from psychosocial interventions, pharmacological treatment is effective for decreasing alcohol consumption and promoting abstinence. However, unique factors belonging to HCV-infected individuals, such as baseline hepatic vulnerability and possible ongoing hepatitis C treatment, complicate AUD drug therapy. The goal of this review is to systematically identify, summarize, and evaluate the existing evidence on the pharmacological management of AUD in HCV-infected individuals. MEDLINE, Embase, PsycINFO, and the Cochrane Central Register of Controlled Trials were searched for English- and French-language articles published from 1993 to December 2013. The search criteria focused on clinical trials and observational studies assessing the efficacy and/or safety of pharmacological management of AUD in patients infected with HCV. Of 421 identified studies, three were included for analysis. Two were observational studies assessing the safety of disulfiram. One was a randomized controlled trial assessing the efficacy and safety of baclofen. There is paucity of data regarding the efficacy and safety of pharmacological treatment of AUD in HCV-infected individuals, with studies being small series and showing significant heterogeneity. No strong recommendations can be made based on the current studies as to which pharmacological option should be preferred in this sub-population.

Acetaldehyde in asymmetric organocatalytic transformations

This review summarize both the recent developments in the organocatalysed use of acetaldehyde as a substrate in various organic transformations and its application in the synthesis of bioactive molecules.

Efficacy of baclofen on abstinence and craving in alcohol-dependent patients: a meta-analysis of randomized controlled trials

PURPOSE

We conducted a meta-analysis in order to estimate the efficacy of baclofen on the maintenance of abstinence and the decrease of craving in alcohol-dependent patients.

METHODS

All randomized controlled clinical trials assessing baclofen for at least four weeks' treatment duration versus placebo or other comparators were included. The primary outcome measure was the percentage of patients who had not consumed alcohol at the end of the treatment. Measures of cumulative abstinence and indexes of craving were also assessed.

RESULTS

Compared to placebo, baclofen was associated with a significant increase of 179% in the percentage of abstinent patients at the end of the trial, without heterogeneity. For secondary outcome measures, based on a random-effect model, no significant effect of baclofen was observed compared to placebo.

CONCLUSIONS

Our meta-analysis brings weak support towards an efficacy of low dosages of baclofen on the maintenance of abstinence in alcohol-dependent patients.

Baclofen for alcohol dependence in France: incidence of treated patients and prescription patterns--a cohort study

Recently, baclofen has been widely promoted for treatment of alcohol dependence in France. Our aim was firstly to describe the incidence of patients newly treated with baclofen for alcohol dependence in France from 2007 to 2011, and secondly to describe baclofen prescription patterns and prescribers. A retrospective cohort study of patients newly treated with baclofen was conducted using the "Echantillon Généraliste des Bénéficiaires" database (EGB). Patients with a first dispensation of baclofen between 01/01/2007 and 31/12/2011, followed by a second in the next 120 days, were included. Patients were considered treated with baclofen for neurological conditions if at least one of the following conditions was found to be true: (1) presence of a neurological condition for which baclofen could be prescribed, (2) dispensation of dantrolene, another anti-spastic drug, or (3) hospitalization for a neurological condition for which baclofen could be prescribed. We assumed that all the remaining patients were treated for alcohol dependence. During the 5-year period, 676 patients were incident users. While the annual incidence rate of patients newly treated with baclofen for neurological conditions remained stable, the annual incidence rate of patients newly treated with baclofen for alcohol dependence increased by a factor of 2.9 between 2007 (0.09/1000 person-years) and 2011 (0.26/1000 person-years). In the alcohol dependence group, median duration of baclofen treatment was 143.5 [74.0; 377.0] days; median daily dose was 24.4 [14.8; 39.5] mg. This study demonstrated the rapidly increasing use of baclofen in France for treatment of alcohol dependence.

Assessing alcohol versus baclofen withdrawal syndrome in patients treated with baclofen for alcohol use disorder

Baclofen is a γ-aminobutyric acid B (GABA-B) receptor agonist that is approved for spasticity. Recently, the off-label use of baclofen for alcohol use disorder (AUD) has increased. However, baclofen is known to induce a neuroadaptation process, which may be identified by the occurrence of a specific baclofen withdrawal syndrome (BWS), that is, confusion, agitation, seizures, and delirium. The same set of symptoms characterizes alcohol withdrawal syndrome (AWS), which could lead to mistaking BWS for AWS in some situations. We report the cases of 3 patients under a chronic baclofen treatment for AUD. The patients emergently presented with a clinical state of confusion that was initially diagnosed and treated as AWS, with limited effect of benzodiazepines. Retrospectively, using a validated algorithm for assessing drug-induced withdrawal, we determined that all of these clinical cases were consistent with BWS. Both AWS and BWS should be considered in the case of acute confusion or delirium occurring in patients treated with baclofen for AUD. Moreover, further research should investigate to what extent GABA-A and GABA-B induce shared or distinct neuroadaptation processes and withdrawal syndromes.

Neural bases of pharmacological treatment of nicotine dependence - insights from functional brain imaging: a systematic review

BACKGROUND

Nicotine dependence is difficult to treat, and the biological mechanisms that are involved are not entirely clear. There is an urgent need to develop better drugs and more effective treatments for clinical practice. A critical step towards accelerating progress in medication development is to understand the neurobehavioral effects of pharmacotherapies on clinical characteristics associated with nicotine dependence.

OBJECTIVES

This review sought to summarize the functional magnetic resonance imaging (fMRI) literature on smoking cessation with the aim to better understand the neural processes underlying the effects of nicotinic and non-nicotinic pharmacological smoking cessation treatments on specific symptoms of nicotine dependence and withdrawal.

DATA SOURCES

We conducted a search in Pubmed, Web of Science and PsycINFO databases with the keywords 'fMRI' or 'functional magnetic resonance imaging' and 'tobacco' or 'nicotine' or 'smok*'. The date of the most recent search was May 2012.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS

The original studies that were included were those of smokers or nicotine-dependent individuals, published in the English language, with pharmacological treatment for nicotine dependence and use of fMRI with blood oxygen level-dependent (BOLD) imaging or continuous arterial spin labelling (CASL). No date limit was applied.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two of the authors read the abstracts of all studies found in the search (n = 1,260). The inclusion and exclusion criteria were applied, and 1,224 articles were excluded. In a second step, the same authors read the remaining 36 studies. Nineteen of the 36 articles were excluded. The results were tabulated by the number of individuals and their mean age, the main sample characteristics, smoking status, study type and methodology, and the main fMRI findings.

RESULTS

Seventeen original fMRI studies involving pharmacological treatment of smokers were selected. The anterior and posterior cingulate cortex, medial and lateral orbitofrontal cortex, ventral striatum, amygdala, thalamus and insula are heavily involved in the maintenance of smoking and nicotine withdrawal. The effects of varenicline and bupropion in alleviating withdrawal symptoms and decreasing smoking correlated with modulation of the activities of these areas. Nicotine replacement therapy seems to improve cognitive symptoms related to withdrawal especially by modulating activities of the default-network regions; however, nicotine replacement does not necessarily alter the activities of neural circuits, such as the cingulate cortices, that are associated with nicotine addiction.

LIMITATIONS

The risk of bias in individual studies, and across studies, was not assessed, and no method of handling data and combining results of studies was carried out. Most importantly, positron emission tomography (PET) studies were not included in this review.

CONCLUSIONS AND IMPLICATION OF KEY FINDINGS

fMRI studies delineate brain systems that contribute to cognitive deficits and reactivity to stimuli that generate the desire to smoke. Nicotinic and non-nicotinic pharmacotherapy may reduce smoking via distinct neural mechanisms of action. These findings should contribute to the development of new medications and discovery of early markers of the therapeutic response of cigarette smokers.

Clinical effectiveness of baclofen for the treatment of alcohol dependence: a review

Baclofen, an agonist at the B subunit of gaba-aminobutyric acid receptor, possesses pharmacologic properties that may confer utility for the treatment of alcohol dependence. Research suggests that not only can it be useful in promoting maintenance of alcohol abstinence but also it may play a key role in decreasing alcohol cravings and anxiety often associated with alcohol dependence. To assess the benefit of baclofen for alcohol dependence, a review of the literature was conducted to identify published data investigating this off-label treatment. Four randomized controlled trials to date have been published and were included in this review. Although primary outcomes differ between studies, patients randomized to baclofen experience higher rates of abstinence from alcohol than those taking placebo in two of the trials. Secondary analyses indicate that baclofen is safe in patients with alcohol dependence, including those with moderate to severe liver cirrhosis, and may provide beneficial anxiolytic effects. Despite some positive data, the largest available randomized controlled trial failed to find any differences between baclofen and placebo. In all studies, individuals with severe medical comorbidities, seizure disorders, and psychiatric disorders were excluded from trials, which may limit external validity. In summary, there may be beneficial effects from using baclofen for the treatment of alcohol dependence; however, limited conclusions can be drawn from the small number of studies currently available for review. Larger well-designed trials are needed to further define baclofen’s role for the treatment of alcohol dependence.

Management of alcohol dependence in patients with liver disease

Alcohol dependence represents a chronic and relapsing disease affecting nearly 10 % of the general population both in the USA and in Europe, with a widespread burden of morbidity and mortality. Alcohol dependence represents the most common cause of liver damage in the Western world. Although alcoholic liver disease is associated primarily with heavy drinking, continued alcohol consumption, even in low doses after the onset of liver disease, increases the risk of severe consequences, including mortality. Consequently, the ideal treatment of patients affected by alcohol dependence and alcoholic liver disease should aim at achieving long-term total alcohol abstinence and preventing relapse. The aim of the present review is to provide an update on the management of alcohol dependence in patients with alcoholic liver disease. Increasing evidence suggests the usefulness of psychosocial interventions and medications combined in order to reduce alcohol intake, promote abstinence and prevent relapse in alcohol-dependent patients. Disulfiram, naltrexone and acamprosate have been approved for this indication; gamma-hydroxybutyric acid (GHB) is approved in Italy and Austria. However, these drugs have not been tested in patients with advanced liver disease. Amongst other emerging pharmacotherapies for alcoholism, topiramate, ondansetron, and baclofen seem the most promising ones. Both topiramate and ondansetron have a safe profile in alcoholic patients; however, none of them has been tested in alcoholic patients with advanced liver disease. To date, baclofen represents the only anti-craving medication formally tested in a randomized clinical trial in alcoholic patients affected by liver cirrhosis, although additional confirmatory studies are warranted.

Efficacy and tolerability of baclofen in substance use disorders: a systematic review

BACKGROUND

It has been reported that baclofen, a drug used in the treatment of spasticity, reduces the severity of withdrawal symptoms and substance use disorders (SUDs) for some psychoactive drugs.

AIMS AND METHODS

To evaluate the effectiveness and safety of baclofen in the treatment of withdrawal syndrome and/or SUDs, providing (1) an outline of its pharmacological features; (2) a summary of studies that have suggested its possible effectiveness in the treatment of SUDs, and (3) a review of randomized, controlled trials (RCTs) on baclofen and SUDs.

RESULTS

Baclofen tolerability is generally considered to be good. Eleven RCTs investigated its effectiveness in the treatment of SUDs. Of these, 5 RCTs found that baclofen is effective, 5 RCTs found that it is ineffective and the results of 1 RCT were not appreciable because it did not achieve the preplanned level of participation.

CONCLUSIONS

The number of RCTs on baclofen and SUDs is still low, and their results are divergent. Further RCTs should be undertaken, particularly with higher doses of baclofen. Its administration may be suggested in patients who fail to respond to other approved drugs or who are affected by liver disease that prevents their administration, or in patients affected by SUDs for which no approved drugs are available. Treatment should be conducted under strict medical supervision.

GABA(B) receptor agonist only reduces ethanol drinking in light-drinking mice

Baclofen, a GABA(B) agonist, reduces ethanol intake in animals and humans, but the contrary or no effect was also reported. Our previous study demonstrated that mice characterized as "loss of control over ethanol intake" had different Gabbr1 and Gabbr2 transcription levels, which express, respectively, the GABA(B1) and GABA(B2) subunits in brain areas related to addictive behavior. In the present study, we tested baclofen on ethanol intake in mice exposed to the free-choice paradigm. Adult male Swiss mice, individually housed, had free access to three bottles: ethanol (5% and 10%) and water. The protocol had four phases: acquisition (AC, 10 weeks), withdrawal (W, 4 cycles during 2 weeks of 2 day-free-choice and 2 day-only-water), reexposure (RE, 2 weeks), and adulteration of ethanol solutions with quinine (AD, 2 weeks). Mice characterized as "loss of control" (A, n=11, preference for ethanol in AC and maintenance of ethanol intake levels in AD), heavy (H, n=11, preference for ethanol in AC and reduction of ethanol intake levels in AD), and light (L, n=16, preference for water in all phases) drinkers were randomly distributed into two subgroups receiving either intraperitoneal injections of all doses of baclofen (1.25, 2.5, and 5.0mg/kg, given each dose twice in consecutive days) or saline, being exposed to free-choice. Fluid consumption was measured 24h later. Baclofen reduced ethanol intake in group L. In group H a reduction compared to AC was observed. Group A maintained their high ethanol intake even after baclofen treatment. Activation of the GABA(B) receptor depends on the precise balance between the GABA(B1) and GABA(B2) subunits, so the disproportionate transcription levels, we reported in group A, could explain this lack of response to baclofen. These data highlight the importance to test baclofen in individuals with different ethanol drinking profiles, including humans.

A transcriptional study in mice with different ethanol-drinking profiles: possible involvement of the GABA(B) receptor

Previous studies have suggested that γ-aminobutyric acid-B (GABA(B)) receptor agonists effectively reduce ethanol intake. The quantification using real-time polymerase chain reaction of Gabbr1 and Gabbr2 mRNA from the prefrontal cortex, hypothalamus, hippocampus, and striatum in mice exposed to an animal model of the addiction developed in our laboratory was performed to evaluate the involvement of the GABA(B) receptor in ethanol consumption. We used outbred, Swiss mice exposed to a three-bottle free-choice model (water, 5% v/v ethanol, and 10% v/v ethanol) that consisted of four phases: acquisition (AC), withdrawal (W), reexposure (RE), and quinine-adulteration (AD). Based on individual ethanol intake, the mice were classified into three groups: "addicted" (A group; preference for ethanol and persistent consumption during all phases), "heavy" (H group; preference for ethanol and a reduction in ethanol intake in the AD phase compared to AC phase), and "light" (L group; preference for water during all phases). In the prefrontal cortex in the A group, we found high Gabbr1 and Gabbr2 transcription levels, with significantly higher Gabbr1 transcription levels compared with the C (ethanol-naive control mice), L, and H groups. In the hippocampus in the A group, Gabbr2 mRNA levels were significantly lower compared with the C, L, and H groups. In the striatum, we found a significant increase in Gabbr1 transcription levels compared with the C, L, and H groups. No differences in Gabbr1 or Gabbr2 transcription levels were observed in the hypothalamus among groups. In summary, Gabbr1 and Gabbr2 transcription levels were altered in cerebral areas related to drug taking only in mice behaviorally classified as "addicted" drinkers, suggesting that these genes may contribute to high and persistent ethanol consumption.

Comparison of the effect of the GABAΒ receptor agonist, baclofen, and the positive allosteric modulator of the GABAB receptor, GS39783, on alcohol self-administration in 3 different lines of alcohol-preferring rats

BACKGROUND

Administration of the GABA(B) receptor agonist, baclofen, and positive allosteric modulator, GS39783, has been repeatedly reported to suppress multiple alcohol-related behaviors, including operant oral alcohol self-administration, in rats. This study was designed to compare the effect of baclofen and GS39783 on alcohol self-administration in 3 lines of selectively bred, alcohol-preferring rats: Indiana alcohol-preferring (P), Sardinian alcohol-preferring (sP), and Alko Alcohol (AA).

METHODS

Rats of each line were initially trained to respond on a lever, on a fixed ratio (FR) 4 (FR4) schedule of reinforcement, to orally self-administer alcohol (15%, v/v) in daily 30-minute sessions. Once responding reached stable levels, rats were exposed to a sequence of experiments testing baclofen (0, 1, 1.7, and 3 mg/kg; i.p.) and GS39783 (0, 25, 50, and 100 mg/kg; i.g.) on FR4 and progressive ratio (PR) schedules of reinforcement. Finally, to assess the specificity of baclofen and GS39783 action, rats were slightly food-deprived and trained to lever-respond for food pellets.

RESULTS

The rank of order of the reinforcing and motivational properties of alcohol was P>sP>AA rats. Under both FR and PR schedules of reinforcement, the rank of order of potency and efficacy of baclofen and GS39783 in suppressing alcohol self-administration was P>sP>AA rats. Only the highest dose of baclofen reduced lever-responding for food pellets; this effect was common to all 3 rat lines. Conversely, no dose of GS39783 altered lever-responding for food in any rat line.

CONCLUSIONS

These results suggest that: (i) the strength of the reinforcing and motivational properties of alcohol differ among P, sP, and AA rats; (ii) the reinforcing and motivational properties of alcohol in P, sP, and AA rats are differentially sensitive to treatment with baclofen and GS39783; (iii) the heterogeneity in sensitivity to baclofen and GS39783 of alcohol self-administration in P, sP, and AA rats may resemble the differential effectiveness of pharmacotherapies among the different typologies of human alcoholics; and (iv) the GABA(B) receptor is part of the neural substrate mediating the reinforcing and motivational properties of alcohol.