Efficacy and safety of alcohol reduction pharmacotherapy according to treatment duration in patients with alcohol dependence or alcohol use disorder: A systematic review and network meta-analysis

BACKGROUND AND AIMS

Relapse is common in alcohol dependence (AD) and alcohol use disorder (AUD), so alcohol reduction therapy should be measured over as long a period as possible; however, existing reviews do not consider the duration of treatment and therefore alcohol reduction therapy may not have been appropriately evaluated. This review evaluated the efficacy and safety of alcohol reduction pharmacotherapy in patients with AD or AUD according to the duration of treatment.

METHODS

We conducted a systematic review and network meta-analysis of randomized controlled trials (RCTs) that assessed 15 pharmacological agents. MEDLINE, Embase, PsycINFO, the Cochrane Central Register of Controlled Trials, the ClinicalTrials.gov and the International Clinical Trials Registry Platform were searched for eligible trials through to May 2021. Outcomes were heavy drinking days (HDD), total alcohol consumption (TAC), any adverse event and days without drinking.

RESULTS

Fifty-five RCTs (n = 8891) were included. Nalmefene was superior to placebo for reducing HDD (standard mean difference [SMD] -0.28, 95% confidence interval [CI] -0.37, -0.18) and TAC (SMD -0.25, 95% CI -0.35, -0.16) in the long-term, but not in the short-term. Topiramate was superior to placebo for reducing HDD (SMD -0.35, 95% CI -0.59, -0.12) and days without drinking (SMD 0.46, 95% CI 0.11, 0.82), and baclofen was superior for reducing TAC (SMD -0.70, 95% CI -1.29, -0.11), in the short-term. The frequency of adverse events was higher with nalmefene and topiramate than with placebo.

CONCLUSION

Nalmefene, topiramate and baclofen may be effective as alcohol reduction pharmacotherapy; however, only nalmefene has demonstrated long-term efficacy, and nalmefene and topiramate have a significantly higher frequency of adverse events compared with placebo.

Substitution therapy for patients with alcohol dependence: Mechanisms of action and efficacy

New approaches for the treatment of alcohol dependence (AD) may improve patient outcomes. Substitution maintenance therapy is one of the most effective treatment options for opioid and nicotine use disorders. So far, there has been little attention to substitution therapy for the treatment of AD. Here, we explain the mechanistic foundations of alcohol substitution maintenance therapy. Alcohol has many primary targets in the brain (and other organs) and the physical interaction of ethanol molecules with these specific ethanol-sensitive sites on a variety of ionotropic receptors (e.g. GABA-A, NMDA, and nicotinic acetylcholine (nACh) receptors) and ion channels provides the rationale for substitution. As such, a variety of compounds can interact with those ethanol-sensitive sites and can thus substitute for some of the effects of alcohol. For some of these compounds, alcohol discrimination studies have shown their substitution potential. Accordingly, potential substitution treatments include agonists acting at GABA receptors such as sodium oxybate, baclofen and benzodiazepines, NMDA receptor antagonists such as ketamine and memantine, or nAChRs agonists such as varenicline. All these compounds are already approved for other indications and we present clinical evidence for these drugs in the treatment of alcohol withdrawal syndrome (AWS) and in the long-term treatment of AD, and outline future steps for their acceptance as substitution treatment in AD. Finally, we discuss the substitution approach of managed alcohol programs for the most severely affected homeless populations. Results showed that sodium oxybate is probably the closest to a substitution therapy for AD and is already approved for the treatment of AWS and in the long-term treatment of AD in some countries. In conclusion, we argue that better AD treatment can be provided if substitution maintenance treatments for alcohol are implemented at a similar scale as for opioid and nicotine use disorder.

Restoring GABAB receptor expression in the ventral tegmental area of methamphetamine addicted mice inhibits locomotor sensitization and drug seeking behavior

Repeated exposure to psychostimulants such as methamphetamine (METH) induces neuronal adaptations in the mesocorticolimbic dopamine system, including the ventral tegmental area (VTA). These changes lead to persistently enhanced neuronal activity causing increased dopamine release and addictive phenotypes. A factor contributing to increased dopaminergic activity in this system appears to be reduced GABAB receptor-mediated neuronal inhibition in the VTA. Dephosphorylation of serine 783 (Ser783) of the GABAB2 subunit by protein phosphatase 2A (PP2A) appears to trigger the downregulation GABAB receptors in psychostimulant-addicted rodents. Therefore, preventing the interaction of GABAB receptors with PP2A using an interfering peptide is a promising strategy to restore GABAB receptor-mediated neuronal inhibition. We have previously developed an interfering peptide (PP2A-Pep) that inhibits the GABAB receptors/PP2A interaction and thereby restores receptor expression under pathological conditions. Here, we tested the hypothesis that restoration of GABAB receptor expression in the VTA of METH addicted mice reduce addictive phenotypes. We found that the expression of GABAB receptors was significantly reduced in the VTA and nucleus accumbens but not in the hippocampus and somatosensory cortex of METH-addicted mice. Infusion of PP2A-Pep into the VTA of METH-addicted mice restored GABAB receptor expression in the VTA and inhibited METH-induced locomotor sensitization as assessed in the open field test. Moreover, administration of PP2A-Pep into the VTA also reduced drug seeking behavior in the conditioned place preference test. These observations underscore the importance of VTA GABAB receptors in controlling addictive phenotypes. Furthermore, this study illustrates the value of interfering peptides targeting diseases-related protein-protein interactions as an alternative approach for a potential development of selective therapeutic interventions.

GABAergic signaling in alcohol use disorder and withdrawal: pathological involvement and therapeutic potential

Alcohol is one of the most widely used substances. Alcohol use accounts for 5.1% of the global disease burden, contributes substantially to societal and economic costs, and leads to approximately 3 million global deaths yearly. Alcohol use disorder (AUD) includes various drinking behavior patterns that lead to short-term or long-lasting effects on health. Ethanol, the main psychoactive molecule acting in alcoholic beverages, directly impacts the GABAergic system, contributing to GABAergic dysregulations that vary depending on the intensity and duration of alcohol consumption. A small number of interventions have been developed that target the GABAergic system, but there are promising future therapeutic avenues to explore. This review provides an overview of the impact of alcohol on the GABAergic system, the current interventions available for AUD that target the GABAergic system, and the novel interventions being explored that in the future could be included among first-line therapies for the treatment of AUD.

Management of Alcohol Use Disorder in Patients With Alcoholic Liver Disease

Alcohol use disorder (AUD) is a common condition that develops on the background of heavy alcohol use and is characterised by the loss of control over alcohol use and a compulsion to use alcohol, often despite negative consequences. AUD is a leading cause for the resumption of alcohol use in patients with alcoholic liver disease (ALD) after treatment. Hence it is essential to screen all patients with ALD for the presence of AUD. Screening tools such as alcohol use disorders identification test (AUDIT) and AUDIT-C are used, following which the diagnosis and severity of AUD are determined using DSM-5 criteria. The management of AUD in patients with ALD is best carried out using an integrated approach involving psychiatrists and gastroenterologists/hepatologists. The treatment most often involves a combination of pharmacotherapy and psychosocial interventions which try to achieve and maintain abstinence. Although, there is limited evidence, Baclofen is the first line pharmacological agent for long-term management of AUD in patients with ALD. Intensive psychological interventions such as motivation enhancement therapy and cognitive behavioural therapy are also seen to be beneficial. Treatment retention and follow-up are vital and can positively influence outcomes.

The effect of GABA-B receptors in the basolateral amygdala on passive avoidance memory impairment induced by MK-801 in rats

MK-801 (dizocilpine) is a potent non-competitive N-methyl-[D]-aspartate (NMDA) receptor antagonist that affects cognitive function, learning, and memory. As we know, NMDA receptors are significantly involved in memory function, as well as GABA (Gamma-Aminobutyric acid) receptors. In this study, we aimed to discover the effect of GABA-B receptors in the basolateral amygdala (BLA) on MK-801-induced memory impairment. We used 160 male Wistar rats. The shuttle box was used to evaluate passive avoidance memory and locomotion apparatus was used to evaluate locomotor activity. MK-801 (0.125, 0.25, and 0.5 μg/rat), baclofen (GABA-B agonist, 0.0001, 0.001, and 0.01 μg/rat) and phaclofen (GABA-B antagonist, 0.0001, 0.001, and 0.01 μg/rat) were injected intra-BLA, after the training. The results showed that MK-801 at the dose of 0.5 μg/rat, baclofen at the doses of 0.001 and 0.01 μg/rat, and phaclofen at the doses of 0.001 and 0.01 μg/rat, impaired passive avoidance memory. Locomotor activity did not alter in all groups. Furthermore, the subthreshold dose of both baclofen (0.0001 μg/rat) and phaclofen (0.0001 μg/rat) restored the impairment effect of MK-801 (0.5 μg/rat) on memory. Also, both baclofen (0.0001 μg/rat) potentiated the impairment effect of MK-801 (0.125 μg/rat) and phaclofen (0.0001 μg/rat) potentiated the impairment effect of MK-801 (0.125 and 0.25 μg/rat) on passive avoidance memory. In conclusion, our results indicated that BLA GABA-B receptors can alter the effect of NMDA inactivation on passive avoidance memory.