Posttreatment effects of topiramate treatment for heavy drinking

Post-treatment effects of topiramate on alcohol-related outcomes: A combined analysis of two placebo-controlled trials

Topiramate reduces drinking and alcohol-related problems and is increasingly being used to treat alcohol use disorder (AUD). In a randomized controlled trial (RCT) of topiramate, rs2832407, a single nucleotide polymorphism (SNP) in the GRIK1 gene moderated topiramate's effects (Study 1). However, a second RCT (Study 2) did not replicate the SNP's moderating effect during treatment. The current analysis combines data from these two studies to examine topiramate's effects on alcohol-related outcomes and on its pharmacogenetic moderation during a 6-month post-treatment period. This analysis includes 308 individuals with problematic alcohol use (67% male; mean age = 51.1; topiramate: 49%, placebo: 51%). It uses generalized linear mixed models to examine changes in self-reported alcohol consumption and alcohol-related problems and concentrations of the liver enzyme γ-glutamyltransferase. The report combines published 3- and 6-month follow-up data from Study 1 with similar, unpublished data from Study 2. Despite robust effects of topiramate on drinking during treatment, the overall multivariate medication effects on outcomes during 3- and 6-month follow-up were not significant (p = 0.08 and p = 0.26, respectively). The moderating effect of the SNP on primary treatment outcomes was also not significant during either follow-up period (p = 0.13 and p = 0.16, respectively). However, during the 3-month post-treatment period, drinks per day was significantly lower in the topiramate group than the placebo group in the rs2832407*CC-genotype group. The robust effects of topiramate on alcohol-related outcomes during treatment diminish substantially once the medication is discontinued. Research is needed both to determine the optimal treatment duration and to identify clinically useful pharmacogenetic moderators of topiramate for treating AUD.

Pharmacogenetics of Addiction Therapy

Drug addiction is a serious relapsing disease that has high costs to society and to the individual addicts. Treatment of these addictions is still in its nascency, with only a few examples of successful therapies. Therapeutic response depends upon genetic, biological, social, and environmental components. A role for genetic makeup in the response to treatment has been shown for several addiction pharmacotherapies with response to treatment based on individual genetic makeup. In this chapter, we will discuss the role of genetics in pharmacotherapies, specifically for cocaine, alcohol, and opioid dependences. The continued elucidation of the role of genetics should aid in the development of new treatments and increase the efficacy of existing treatments.

Antagonism of GluK1-containing kainate receptors reduces ethanol consumption by modulating ethanol reward and withdrawal

Alcohol use disorder (AUD) is a neuropsychiatric condition affecting millions of people worldwide. Topiramate (TPM) is an antiepileptic drug that has been shown to reduce ethanol drinking in humans. However, TPM is associated with a variety of adverse effects due to its interaction with many receptor systems and intracellular pathways. GluK1-containing kainate receptors (GluK1*KARs) are non-selectively inhibited by TPM, and genetic association studies suggest that this receptor system could be targeted to reduce drinking in AUD patients. We examined the efficacy of LY466195, a selective inhibitor of GluK1*KAR, in reducing ethanol consumption in the intermittent two-bottle choice paradigm in mice. The effect of LY466195 on various ethanol-related phenotypes was investigated by quantification of alcohol intake, physical signs of withdrawal, conditioned place preference (CPP) and in vivo microdialysis in the nucleus accumbens. Selective GluK1*KAR inhibition reduced ethanol intake and preference in a dose-dependent manner. LY466195 treatment attenuated the physical manifestations of ethanol withdrawal and influenced the rewarding properties of ethanol. Interestingly, LY466195 injection also normalized changes in dopamine levels in response to acute ethanol in ethanol-dependent mice, but had no effect in ethanol-naïve mice, suggesting ethanol state-dependent effects. The data point to GluK1*KARs as an attractive pharmacological target for the treatment of AUD.

Use of Topiramate in the Spectrum of Addictive and Eating Disorders: A Systematic Review Comparing Treatment Schemes, Efficacy, and Safety Features

BACKGROUND AND OBJECTIVE

Topiramate has been approved by the US Food and Drug Administration for the treatment of epilepsy since the 1990s, and it has also been used off-label in the treatment of many types of addictive disorders. To date, no systematic review has embraced the entire field of addiction, both substance use and behavioral addictions, including eating disorders, to compare topiramate-based protocols and the related level of evidence in each addictive disorder. Our objective is to fill this gap.

METHODS

A systematic search was conducted using the MEDLINE, PsycINFO, and Cochrane databases without a date or language limit. All trials and meta-analyses assessing the efficacy of topiramate in alcohol use disorder; cocaine use disorder; methamphetamine, nicotine, cannabis, opiate, and benzodiazepine use disorders; binge eating disorder; bulimia; and pathological gambling were analyzed. The quality of the studies was rated using the Cochrane Risk-of-Bias tool for randomized trials (ROB-2), the Risk of Bias In Nonrandomized Studies (ROBINS-I), or the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, depending on the study design. Safety features were assessed based on a wider non-systematic review.

RESULTS

Sixty-two articles were reviewed. Treatment protocols were relatively homogenous across addictive disorders, with slow dose titration schemes and a maximum dose range of 200-400 mg per day. The most supportive evidence for topiramate efficacy was found in alcohol use disorder for drinking reduction parameters only. To a lesser extent, topiramate could be a promising therapeutic option for binge eating disorder and cocaine use disorder. Evidence was weak for other addictive disorders. No major tolerability issues were found, provided that basic safety rules were followed. Adverse drug reactions could lead to early treatment discontinuation.

DISCUSSION

Though off-label, addiction specialists should consider topiramate as a second-line option for drinking reduction in alcohol use disorder, as well as for binge eating disorder or cocaine use disorder.

Induced pluripotent stem cell reprogramming-associated methylation at the GABRA2 promoter and chr4p12 GABAA subunit gene expression in the context of alcohol use disorder

Twin studies indicate that there is a significant genetic contribution to the risk of developing alcohol use disorder (AUD). With the exception of coding variants in ADH1B and ALDH2, little is known about the molecular effects of AUD-associated loci. We previously reported that the AUD-associated synonymous polymorphism rs279858 within the GABAA α2 receptor subunit gene, GABRA2, was associated with gene expression of the chr4p12 GABAA subunit gene cluster in induced pluripotent stem cell (iPSC)-derived neural cultures. Based on this and other studies that showed changes in GABRA2 DNA methylation associated with schizophrenia and aging, we examined methylation in GABRA2. Specifically, using 69 iPSC lines and neural cultures derived from 47 of them, we examined whether GABRA2 rs279858 genotype predicted methylation levels and whether methylation was related to GABAA receptor subunit gene expression. We found that the GABRA2 CpG island undergoes random stochastic methylation during reprogramming and that methylation is associated with decreased GABRA2 gene expression, an effect that extends to the GABRB1 gene over 600 kb distal to GABRA2. Further, we identified additive effects of GABRA2 CpG methylation and GABRA2 rs279858 genotype on expression of the GABRB1 subunit gene in iPSC-derived neural cultures.

Molecular Correlates of Topiramate and GRIK1 rs2832407 Genotype in Pluripotent Stem Cell-Derived Neural Cultures

BACKGROUND

There is growing evidence that the anticonvulsant topiramate is efficacious in reducing alcohol consumption. Further, an intronic single nucleotide polymorphism (rs2832407, C A) in the GRIK1 gene, which encodes the GluK1 subunit of the excitatory kainate receptor, predicted topiramate's effectiveness in reducing heavy drinking in a clinical trial. The molecular correlates of GRIK1 genotype that may relate to topiramate's ability to reduce drinking remain unknown.

METHODS

We differentiated induced pluripotent stem cells (iPSCs) characterized by GRIK1 rs2832407 genotype from 8 A/A and 8 C/C donors into forebrain-lineage neural cultures. Our differentiation protocol yielded mixed neural cultures enriched for glutamatergic neurons. Basal mRNA expression of the GRIK1 locus was examined via quantitative polymerase chain reaction (qPCR). The effects of acute topiramate exposure on excitatory spontaneous synaptic activity were examined via whole-cell patch-clamp electrophysiology. Results were compared and contrasted between iPSC donor genotypes.

RESULTS

Although characterization of the GRIK1 locus revealed no effect of rs2832407 genotype on GRIK1 isoform mRNA expression, a significant difference was observed on GRIK1 antisense-2 expression, which was greater in C/C neural cultures. Differential effects of acute exposure to 5 μM topiramate were observed on spontaneous synaptic activity in A/A versus C/C neurons, with a smaller reduction in excitatory event frequency observed in C/C donor neurons.

CONCLUSIONS

This work highlights the use of iPSC technologies to study pharmacogenetic treatment effects in psychiatric disorders and furthers our understanding of the molecular effects of topiramate exposure in human neural cells.

Topiramate Pharmacotherapy for Alcohol Use Disorder and Other Addictions: A Narrative Review

: Topiramate is a non-benzodiazepine anticonvulsant medication with multi-faceted pharmacologic action. It has emerged as an efficacious pharmacotherapeutic option for the treatment of addiction, especially alcohol use disorder (AUD). We present a broad narrative review of the putative mechanism of action and clinical utility of topiramate with regard to AUD and other substance use disorders. Collective evidence suggests topiramate is an effective treatment option in AUD, with notable efficacy in reducing harmful drinking patterns in AUD. Though not currently approved by the United States Food and Drug Administration for the indication of AUD, topiramate should be considered as a pharmacological treatment option with high utility among AUD patients. Early pharmacogenetic studies raise the intriguing possibility of identifying patients likely to respond to topiramate using genetic testing, and initial studies show that topiramate may also be useful in treating cocaine use disorder, smoking cessation and behavioral addictions. However, further research is needed in all these areas.

Clinical Trials for Stimulant Use Disorders: Addressing Heterogeneities That May Undermine Treatment Outcomes

In recent years, use of cocaine and amphetamines and deaths associated with stimulants have been on the rise, and there are still no FDA-approved medications for stimulant use disorders. One contributing factor may involve heterogeneity. At the neurobiological level, dual dopamine dysfunction may be undermining medication efficacy, suggesting a need for combination pharmacotherapies. At the population level, individual variability is expressed in a number of ways and, if left unaddressed, may interfere with medication efficacy. This chapter reviews studies investigating medications to address dopamine dysfunction, and it also identifies several prominent heterogeneities associated with stimulant (and other substance) use disorders. The chapter has implications for improving interventions to treat stimulant use disorders, and the theme of individual heterogeneity may have broader application across substance use disorders.

On the path towards personalized medicine: Implications of pharmacogenetic studies of alcohol use disorder medications

Introduction

The heritability of alcohol use disorder (AUD) is estimated to be ~50%; however, the genetic basis of the disease is still poorly understood. The genetic variants identified thus far only explain a small percentage of AUD phenotypic variability. While genome-wide association studies (GWAS) are impacted by technical and methodological limitations, genetic variants that have been identified independently of GWAS findings can moderate the efficacy of AUD medications.

Areas Covered

This review discusses findings from clinical pharmacogenetic studies of AUD medications. While the pharmacogenetic studies reviewed involve several genetic variants in the major neurotransmitter systems, genetic loci in the opioid system have garnered the most attention.

Expert Opinion

The clinical utility of pharmacogenetics in AUD populations is uncertain at this time. There are several ongoing prospective clinical trials that will enhance knowledge regarding the applicability of pharmacogenetics in clinical populations. We recommend that future work in this area consider reverse translating from genotype to phenotype, mapping genes to stages of the addiction cycle, mapping genes to neural circuits, and harnessing large population-based cohorts.

Pharmacogenetics of alcohol use disorder treatments: an update

Introduction: Alcohol use disorder (AUD) is highly prevalent; costly economically, socially, and interpersonally; and grossly undertreated. The low rate of utilization of medications with demonstrated (albeit modest) efficacy is particularly noteworthy. One approach to increasing the utility and safety of available medications is to use a precision medicine approach, which seeks to identify patients for whom specific medications are likely to be most efficacious and have the fewest adverse effects. Areas Covered: We review the literature on the pharmacogenetics of AUD treatment using both approved and off-label medications. We cover both laboratory studies and clinical trials, highlighting valuable mechanistic insights and underscoring the potential value of precision-based care for AUD. Expert Opinion: Pharmacotherapy can be a useful component of AUD treatment. Currently, the evidence regarding genetic predictors of medication efficacy is very limited. Thus, a precision medicine approach is not yet ready for widespread clinical implementation. Further research is needed to identify candidate genetic variants that moderate the response to both established and novel medications. The growing availability of large-scale, longitudinal datasets that enable the synthesis of genetic and electronic health record data provides important opportunities to develop this area of research.

Double-Blind Randomized Clinical Trial of Prazosin for Alcohol Use Disorder

OBJECTIVE

Current medications for alcohol use disorder do not target brain noradrenergic pathways. Theoretical and preclinical evidence suggests that noradrenergic circuits may be involved in alcohol reinforcement and relapse. After a positive pilot study, the authors tested the α-1 adrenergic receptor antagonist prazosin to treat alcohol use disorder in a larger sample.

METHOD

Ninety-two participants with alcohol use disorder but without posttraumatic stress disorder were randomly assigned to receive prazosin or placebo in a 12-week double-blind study. Medication was titrated to a target dosing schedule of 4 mg in the morning, 4 mg in the afternoon, and 8 mg at bedtime by the end of week 2. The behavioral platform was medical management. Participants provided daily data on alcohol consumption. Generalized linear mixed-effects models were used to examine the impact of prazosin compared with placebo on number of drinks per week, number of drinking days per week, and number of heavy drinking days per week.

RESULTS

Eighty participants completed the titration period and were included in the primary analyses. There was a significant interaction between condition and week for both number of drinks and number of heavy drinking days, such that the rate of drinking and the probability of heavy drinking showed a greater decrease over time for participants in the prazosin condition compared with those in the placebo condition. Participants in the prazosin condition were more likely to report drowsiness and edema than participants in the placebo condition.

CONCLUSIONS

Prazosin holds promise as a harm-reduction pharmacologic treatment for alcohol use disorder and deserves further evaluation by independent research groups.

Receipt of alcohol-related care among patients with HCV and unhealthy alcohol use

BACKGROUND

Alcohol use-particularly unhealthy alcohol use-exacerbates risks associated with Hepatitis C virus (HCV). However, whether unhealthy alcohol use is appropriately addressed among HCV+ patients is understudied. We examined receipt of alcohol-related care among HCV+ patients and unhealthy alcohol use.

METHODS

All positive alcohol screens (AUDIT-C score ≥5) documented 10/01/09-5/30/13 were identified from national electronic health records data from the Veterans Health Administration (VA). Regression models estimated unadjusted and adjusted proportions of HCV+ and HCV- patients receiving 1) brief intervention within 14 days of positive screening, 2) specialty addictions treatment, and 3) pharmacotherapy for alcohol use disorder (AUD) in the year following positive screening. Adjusted models included demographics, alcohol use severity, and mental health and substance use disorder comorbidities.

RESULTS

Among 830,825 VA outpatients with positive alcohol screening, 31,841 were HCV+. Among HCV+, unadjusted and adjusted prevalences were 69.2% (CI, 68.7-69.6) and 71.9% (CI, 71.4-72.4) for brief intervention, 29.9% (CI, 29.4-30.4) and 12.7% (CI 12.5-12.9) for specialty addictions treatment, and 5.9% (CI, 5.7-6.1) and 3.3% (CI, 3.1-3.4) for pharmacotherapy, respectively. Among the 20,320 (64%) patients with HCV and documented AUD, unadjusted and adjusted prevalences were 40.0% (CI, 39.3-40.6) and 26.7% (CI, 26.3-27.1) for specialty addictions treatment and 8.1% (CI, 7.7-8.4) and 6.4% (CI, 6.1-6.6) for pharmacotherapy, respectively. Receipt of alcohol-related care was generally similar across HCV status.

CONCLUSIONS

Findings highlight under-receipt of recommended alcohol-related care, particularly pharmacotherapy, among patients with HCV and unhealthy alcohol use who are particularly vulnerable to adverse influences of alcohol use.

GABA and Glutamate Synaptic Coadaptations to Chronic Ethanol in the Striatum

Alcohol (ethanol) is a widely used and abused drug with approximately 90% of adults over the age of 18 consuming alcohol at some point in their lifetime. Alcohol exerts its actions through multiple neurotransmitter systems within the brain, most notably the GABAergic and glutamatergic systems. Alcohol's actions on GABAergic and glutamatergic neurotransmission have been suggested to underlie the acute behavioral effects of ethanol. The striatum is the primary input nucleus of the basal ganglia that plays a role in motor and reward systems. The effect of ethanol on GABAergic and glutamatergic neurotransmission within striatal circuitry has been thought to underlie ethanol taking, seeking, withdrawal and relapse. This chapter reviews the effects of ethanol on GABAergic and glutamatergic transmission, highlighting the dynamic changes in striatal circuitry from acute to chronic exposure and withdrawal.

Guidelines for biological treatment of substance use and related disorders, part 1: Alcoholism, first revision

These practice guidelines for the biological treatment of alcohol use disorders are an update of the first edition, published in 2008, which was developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). For this 2016 revision, we performed a systematic review (MEDLINE/PUBMED database, Cochrane Library) of all available publications pertaining to the biological treatment of alcoholism and extracted data from national guidelines. The Task Force evaluated the identified literature with respect to the strength of evidence for the efficacy of each medication and subsequently categorised it into six levels of evidence (A-F) and five levels of recommendation (1-5). Thus, the current guidelines provide a clinically and scientifically relevant, evidence-based update of our earlier recommendations. These guidelines are intended for use by clinicians and practitioners who evaluate and treat people with alcohol use disorders and are primarily concerned with the biological treatment of adults with such disorders.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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