Combined pharmacotherapies for the management of alcoholism: rationale and evidence to date

Neuroimmune modulators as novel pharmacotherapies for substance use disorders

One promising avenue of research is the use of neuroimmune modulators to treat substance use disorders (SUDs). Neuroimmune modulators target the interactions between the nervous system and immune system, which have been found to play a crucial role in the development and maintenance of SUDs. Multiple classes of substances produce alterations to neuroimmune signaling and peripheral immune function, including alcohol, opioids, and psychostimulants Preclinical studies have shown that neuroimmune modulators can reduce drug-seeking behavior and prevent relapse in animal models of SUDs. Additionally, early-phase clinical trials have demonstrated the safety and feasibility of using neuroimmune modulators as a treatment for SUDs in humans. These therapeutics can be used as stand-alone treatments or as adjunctive. This review summarizes the current state of the field and provides future directions with a specific focus on personalized medicine.

Efficacy of Combining Varenicline and Naltrexone for Smoking Cessation and Drinking Reduction: A Randomized Clinical Trial

OBJECTIVE

Pharmacological treatments that can concomitantly address cigarette smoking and heavy drinking stand to improve health care delivery for these highly prevalent co-occurring conditions. This superiority trial compared the combination of varenicline and naltrexone against varenicline alone for smoking cessation and drinking reduction among heavy-drinking smokers.

METHODS

This was a phase 2 randomized double-blind clinical trial. Participants (N=165) who were daily smokers and drank heavily received either 2 mg/day of varenicline plus 50 mg/day of naltrexone or 2 mg/day of varenicline plus matched placebo pills for 12 weeks. Primary outcomes were 7-day point prevalence of nicotine abstinence (bioverified by a breath CO reading ≤5 ppm) at the 26-week follow-up and number of drinks per drinking day during the 12-week treatment phase.

RESULTS

Smoking abstinence at week 26 was significantly higher in the varenicline plus placebo condition than in the varenicline plus naltrexone condition (N=37 [45.1%] compared with N=22 [26.5%]). For drinks per drinking day, there was a medication effect favoring the combination of varenicline and naltrexone over varenicline alone across the 12-week treatment phase, although it did not meet the significance threshold.

CONCLUSIONS

These findings suggest that smoking cessation and drinking reduction can be concomitantly targeted with pharmacotherapy and that while varenicline alone may be sufficient as a smoking cessation aid in heavy-drinking smokers, the combination of varenicline and naltrexone may confer benefits with regard to drinking outcomes, particularly during the 12-week period of active medication treatment.

Topiramate-phentermine combinations reduce cocaine self-administration in humans

RATIONALE

Cocaine use disorder is an unrelenting public health concern. Despite nearly four decades of research, an FDA approved medication is not yet available.

OBJECTIVES

The objective of this human laboratory study was to demonstrate the initial efficacy, safety and tolerability of topiramate-phentermine combinations for cocaine use disorder.

METHODS

Thirty-one (31) participants with cocaine use disorder completed this mixed-model inpatient laboratory study. Participants were maintained on topiramate (0 [N = 11], 50 [N = 9] or 100 [N = 11] mg/day). Each topiramate group was concurrently maintained on phentermine (0, 15, 30 mg). Drug self-administration, subjective responses and cardiovascular effects following acute doses of intranasal cocaine (0, 40, 80 mg) were determined during separate experimental sessions after at least seven (7) days of maintenance on each condition.

RESULTS

The three groups of participants were well matched demographically and generally did not differ significantly in their responses to a range of doses of intranasal cocaine (0, 10, 20, 40, 80 mg) during a medical safety session. Maintenance on topiramate and phentermine alone significantly decreased cocaine self-administration although these effects were modest in magnitude. Combining topiramate and phentermine robustly decreased cocaine self-administration. Topiramate and phentermine were well tolerated alone and combined, as well as in conjunction with cocaine.

CONCLUSIONS

The results of the present study support advancing topiramate-phentermine combinations as a putative pharmacotherapeutic for cocaine use disorder.

Comparing and Combining Topiramate and Aripiprazole on Alcohol-Related Outcomes in a Human Laboratory Study

Aims

The goal of this study was to evaluate the efficacy of topiramate up to 200 mg/day and of aripiprazole up to 15 mg/day, alone and combined, in reducing alcohol-related outcomes in a human laboratory study.

Method

This was a 5 week, between-subject, double-blind, placebo-controlled human laboratory study with topiramate [0 mg/day (placebo), 100 mg/day, 200 mg/day] and aripiprazole [0 mg/day (placebo), 7.5 mg/day, 15 mg/day] in 90 non-treatment seeking, heavy drinking, alcohol-dependent individuals. Main outcomes were the efficacy of 200 mg/day topiramate and 15 mg/day aripiprazole, alone and combined, in reducing drinks consumed during an alcohol self-administration procedure (human laboratory phase) and while receiving the study medications prior to the laboratory session (naturalistic drinking phase). Other outcomes in the laboratory phase included alcohol craving, and alcohol biphasic effects.

Results

In the human laboratory phase, topiramate 200 mg/day reduced alcohol craving [**P < 0.01] and amplified alcohol-induced stimulation [*P < 0.05], but did not reduce the number of drinks consumed. Topiramate 200 mg/day was also effective in reducing drinking days [*P < 0.05], and alcohol craving [*P < 0.05], in the naturalistic drinking phase. No significant findings were found for aripiprazole for any of the outcomes analyzed.

Conclusion

Participants receiving 200 mg/day topiramate reported reduced alcohol drinking and craving, and increased alcohol-related stimulation. These findings provide further support for the role of topiramate as a pharmacological treatment for AUD.

ClinicalTrial.gov Identifier

NCT00884884.

Short Summary

This study tested topiramate and aripiprazole alone and in combination. The results replicate past findings and suggest that topiramate may be an effective treatment for alcohol use disorder. The present results suggest that the combination of topiramate and aripiprazole do not warrant further evaluation.

Effects of cannabidiol plus naltrexone on motivation and ethanol consumption

BACKGROUND AND PURPOSE

The aim of this study was to explore if the administration of naltrexone together with cannabidiol (CBD) may improve the efficacy in reducing alcohol consumption and motivation rather than any of the drugs given separately.

EXPERIMENTAL APPROACH

The effects of low doses of naltrexone (0.7 mg·kg^-1 , p.o.) and/or CBD (20 mg·kg^-1 ·day^-1 , s.c.) on ethanol consumption and motivation to drink were evaluated in the oral-ethanol self-administration paradigm in C57BL/6 mice. Gene expression analyses of the opioid μ receptor (Oprm1) in the nucleus accumbens (NAc), tyrosine hydroxylase (TH) in the ventral tegmental area (VTA) and the 5-HT_1A receptor in the dorsal raphe nucleus (DR) were carried out by real-time PCR. The role of 5-HT_1A receptors in the ethanol reduction induced by the administration of CBD + naltrexone was analysed by using the 5-HT_1A receptor antagonist WAY100635 (0.3 mg·kg^-1 , i.p.).

KEY RESULTS

The administration of CBD + naltrexone significantly reduced motivation and ethanol intake in the oral self-administration procedure in a greater proportion than the drugs given alone. Only the combination of both drugs significantly reduced Oprm1, TH and 5-HT_1A gene expressions in the NAc, VTA and DR respectively. Interestingly, the administration of WAY100635 significantly blocked the actions of CBD + naltrexone but had no effects by itself.

CONCLUSION AND IMPLICATIONS

The combination of low doses of CBD plus naltrexone were more effective than either CBD or naltrexone alone at reducing ethanol consumption and the motivation to drink. These effects appear to be mediated, at least in part, by 5-HT_1A receptors.

Systematic Review of Combined Pharmacotherapy for the Treatment of Alcohol Use Disorder in Patients Without Comorbid Conditions

BACKGROUND

Previous reviews have examined the use of theoretically supported combinations of drugs for the treatment of alcohol use disorder. This review seeks to examine the strengths and limitations of current clinical evidence for the use of combined pharmacological interventions intended to treat alcohol use disorder.

OBJECTIVES

The objective of this review was to identify combinations of pharmacological treatments for alcohol use disorder, and assess the strength of clinical evidence for these treatments.

METHODS

We conducted searches using PubMed, EMBASE^® through Ovid^® (1974 to present), MEDLINE^® through Ovid^® (1946 to present), and Psychinfo^® through Ovid^® (1806 to present). Our primary search included the terms "alcoholism" and "drug therapy, combination". Search results were restricted to human subjects and English language. Search criteria were not restricted based on study design or patient age. Studies were evaluated for randomization, blinding, group similarity, power determination, outcome reporting, and number of patients analyzed.

RESULTS

Nine hundred and eighty-four publications were initially screened for inclusion after duplicates were removed. The search identified 16 publications evaluating drug combinations for the treatment of alcohol use disorder. The majority of published trials included naltrexone combined with one of the following: gabapentin, ondansetron, acamprosate, gamma-hydroxybutyrate, sertraline, quetiapine, or escitalopram plus gamma-hydroxybutyrate. Other combinations included 5-hydroxytryptophan with carbidopa/levodopa, gamma-hydroxybutyrate with disulfiram, acamprosate with disulfiram, and mirtazapine with quetiapine. Interpretation of results across studies was limited by low statistical power, and heterogeneity of drug combinations and outcome measures. Drug combination effect sizes were comparable to those observed in single-agent trials.

CONCLUSIONS

No significant benefit for the use of combinations over single agents was observed. However, benefit may be observed when combined pharmacological interventions address specific symptoms of alcohol use disorder known to be influenced by combination components, or when combinations are used in specific subpopulations in which combination components demonstrate benefit.

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.

Nutrition and Muscle in Cirrhosis

As the cirrhosis progresses, development of complication like ascites, hepatic encephalopathy, variceal bleeding, kidney dysfunction, and hepatocellular carcinoma signify increasing risk of short term mortality. Malnutrition and muscle wasting (sarcopenia) is yet other complications that negatively impact survival, quality of life, and response to stressors, such as infection and surgery in patients with cirrhosis. Conventionally, these are not routinely looked for, because nutritional assessment can be a difficult especially if there is associated fluid retention and/or obesity. Patients with cirrhosis may have a combination of loss of skeletal muscle and gain of adipose tissue, culminating in the condition of "sarcopenic obesity." Sarcopenia in cirrhotic patients has been associated with increased mortality, sepsis complications, hyperammonemia, overt hepatic encephalopathy, and increased length of stay after liver transplantation. Assessment of muscles with cross-sectional imaging studies has become an attractive index of nutritional status evaluation in cirrhosis, as sarcopenia, the major component of malnutrition, is primarily responsible for the adverse clinical consequences seen in patients with liver disease. Cirrhosis is a state of accelerated starvation, with increased gluconeogenesis that requires amino acid diversion from other metabolic functions. Protein homeostasis is disturbed in cirrhosis due to several factors such as hyperammonemia, hormonal, and cytokine abnormalities, physical inactivity and direct effects of ethanol and its metabolites. New approaches to manage sarcopenia are being evolved. Branched chain amino acid supplementation, Myostatin inhibitors, and mitochondrial protective agents are currently in various stages of evaluation in preclinical studies to prevent and reverse sarcopenia, in cirrhosis.

Sarcopenia in Alcoholic Liver Disease: Clinical and Molecular Advances

Despite advances in treatment of alcohol use disorders that focus on increasing abstinence and reducing recidivism, alcoholic liver disease (ALD) is projected to be the major cause of cirrhosis and its complications. Malnutrition is recognized as the most frequent complication in ALD, and despite the high clinical significance, there are no effective therapies to reverse malnutrition in ALD. Malnutrition is a relatively imprecise term, and sarcopenia or skeletal muscle loss, the major component of malnutrition, is primarily responsible for the adverse clinical consequences in patients with liver disease. It is, therefore, critical to define the specific abnormality (sarcopenia) rather than malnutrition in ALD, so that therapies targeting sarcopenia can be developed. Skeletal muscle mass is maintained by a balance between protein synthesis and proteolysis. Both direct effects of ethanol (EtOH) and its metabolites on the skeletal muscle and the consequences of liver disease result in disturbed proteostasis (protein homeostasis) and consequent sarcopenia. Once cirrhosis develops in patients with ALD, abstinence is unlikely to be effective in completely reversing sarcopenia, as other contributors including hyperammonemia, hormonal, and cytokine abnormalities aggravate sarcopenia and maintain a state of anabolic resistance initiated by EtOH. Cirrhosis is also a state of accelerated starvation, with increased gluconeogenesis that requires amino acid diversion from signaling and substrate functions. Novel therapeutic options are being recognized that are likely to supplant the current "deficiency replacement" approach and instead focus on specific molecular perturbations, given the increasing availability of small molecules that can target specific signaling components. Myostatin antagonists, leucine supplementation, and mitochondrial protective agents are currently in various stages of evaluation in preclinical studies to prevent and reverse sarcopenia, in cirrhosis in general, and ALD, specifically. Translation of these data to human studies and clinical application requires priority for allocation of resources.

Sodium oxybate plus nalmefene for the treatment of alcohol use disorder: A case series

The treatment of alcohol use disorder still remains a challenge. The efficacy of the combined pharmacological treatment for alcohol use disorder has been widely investigated with controversial results. The aim of our case series was to investigate the effect of nalmefene in patients not responding to sodium oxybate therapy. We describe seven cases of consecutive patients affected by alcohol use disorder, and treated with sodium oxybate (50 mg/kg per day) who did not achieve complete alcohol abstinence after at least one month of pharmacological treatment. Then, in partial- and non-responder patients to sodium oxybate treatment, administration of nalmefene, 18 mg as needed, was commenced. Our data show that, during the first month of the combined treatment of sodium oxybate plus nalmefene, patients were able to achieve alcohol abstinence (two patients), to suppress (five cases) or reduce (two patients) episodes of heavy drinking days, and to suppress the onset of craving for sodium oxybate (one patient). Likely, nalmefene may act in modulating the excessive reward effect of sodium oxybate, which may be responsible for the persistence of alcohol intake and for the onset of craving for sodium oxybate. However, controlled clinical trials to confirm the safety and efficacy of sodium oxybate plus nalmefene in treating alcohol use disorder are warranted.

Management of Alcohol Use Disorder in Patients Requiring Liver Transplant

Alcoholic liver disease is the second most common indication for orthotopic liver transplantation in western countries. The majority of patients with alcoholic liver disease, however, are not referred for transplant evaluation. If evaluated, a 6 month period of sobriety is required before waitlisting for transplant. The consequences of relapse to alcohol use in patients on the waitlist are usually removal from the list. Therefore, identification and treatment of alcohol use disorder in patients with end-stage liver disease greatly impacts quality of life, treatment options and survival in patients’ course with this grave illness. Psychosocial and behavioral interventions prior to transplant appear to reduce drinking in the period before the surgery as well as reduce relapse rates post-transplant. Only one of the three medications approved by the Food and Drug Administration, acamprosate, seems feasible for use in patients with end-stage liver disease, while several other medications currently under investigation for the treatment of alcohol use disorder can be considered for use in this population. While only baclofen has been formally studied in alcoholic patients with end-stage liver disease with positive results for safety and efficacy, other medications also hold promise to treat alcohol use disorder in this population. Transplant programs with addictions specialists who function as an integral part of the treatment team may offer better outcomes to patients in terms of success of maintaining sobriety both pre- and post-transplant.

Investigational therapies for the pharmacological treatment of alcoholism

Introduction: Alcohol dependence is one of the most important psychiatric disorders leading to enormous harm in individuals and indeed within society. Yet, although alcohol dependence is a disease of significant importance, the availability of efficacious pharmacological treatment is still limited. Areas covered: The current review focuses on neurobiological pathways that are the rationale for recent preclinical and clinical studies testing novel compounds that could be used as treatments for alcohol dependence. These neurobiological mechanisms include the: glutamatergic, dopaminergic and GABA mediated pathways as well as neuroendocrine systems. There is also an interest in the approaches for influencing chromatin structure. Expert opinion: There are several compounds in Phase I and Phase II clinical studies that have produced potentially useful results for the treating alcoholism. Further evaluation is still necessary, and the implementation of Phase III studies will help to elucidate the usefulness of these compounds. It is important that personalized approaches (e.g., pharmacogenomics) are investigated in these later studies, as the efficacy of different compounds may vary substantially between subgroups of patients.