Topiramate versus naltrexone for alcohol use disorder: study protocol for a genotype-stratified, double-blind randomised controlled trial (TOP study)

Neural cue reactivity and intrinsic functional connectivity in individuals with alcohol use disorder following treatment with topiramate or naltrexone

RATIONALE

Both topiramate and naltrexone have been shown to affect neural alcohol cue reactivity in alcohol use disorder (AUD). However, their comparative effects on alcohol cue reactivity are unknown. Moreover, while naltrexone has been found to normalize hyperactive localized network connectivity implicated in AUD, no studies have examined the effect of topiramate on intrinsic functional connectivity or compared functional connectivity between these two widely used medications.

OBJECTIVE

This study compared topiramate versus naltrexone on alcohol cue-elicited brain activation and intrinsic functional connectivity in patients with alcohol use disorder.

METHODS

Forty-seven participants with alcohol use disorder received daily topiramate (titrating the dose up to 200 mg/day n = 21) or naltrexone (50 mg/day, n = 26) for at least 6 weeks. Using functional magnetic resonance imaging (fMRI), we examined intrinsic functional connectivity during rest and alcohol cue-elicited neural activation during a visual alcohol cue reactivity task 120 min following treatment administration. Functional connectivity and alcohol cue reactivity and percentage of heavy drinking days (% HDD) associations were assessed.

RESULTS

No differences in either intrinsic functional connectivity or alcohol cue-elicited neural activity were seen between topiramate and naltrexone-treated groups. Overall, participants showed increased alcohol cue-elicited activation in three clusters spanning occipital regions involved in visual recognition of stimuli, and hypoactivation to both alcohol and control cues in three clusters involved in salience attribution and processing of emotional valence of external stimuli. No differences between topiramate versus naltrexone were observed for either functional measure or associations with post-scan % HDD.

CONCLUSIONS

Topiramate and naltrexone enacted comparable alcohol cue reactivity and intrinsic functional connectivity patterns. Some overall responses of increased brain activation to alcohol cues in visual processing regions coupled with reduced activation to alcohol and control cues were evidenced for both treatments. These activation patterns were in regions expected to show attenuation of brain activity resulting from treatment. Topiramate and naltrexone may thus enact functional effects through similar modulation of functional neural activity in individuals with AUD.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03479086 https://www.

CLINICALTRIALS

gov/study/NCT03479086 .

Comparative effects of topiramate and naltrexone on neural activity during anticipatory anxiety in individuals with alcohol use disorder

Topiramate has been found to be effective in reducing alcohol use and may also attenuate anxiety severity in patients with alcohol use disorder (AUD). This study compared the neural response of treatment-seeking patients with AUD on either topiramate or naltrexone during an anticipatory anxiety task. Participants were 42 patients with AUD who were randomized to receive either topiramate (n = 23; titrated dose up to 200 mg/day) or naltrexone (n = 19; 50 mg/day) for 12-weeks as part of a larger randomized controlled trial. Following 6 weeks of treatment, participants completed an anticipatory anxiety task during a functional magnetic resonance imaging (fMRI) session. The task presented a series of high-threat and low-threat stimuli followed by an unpleasant or pleasant image, respectively. Primary whole-brain analyses revealed no significant differences in neural activation between the topiramate and naltrexone groups. Deactivation for safe cues relative to threat cues was observed within the precuneus, inferior parietal lobule and the cingulate gyrus. In the precentral and middle frontal gyri, threat cues elicited greater activation. Exploratory analyses revealed an effect of change in anxiety from baseline to week 6, with a greater reduction associated with a reduced response to threat cues relative to safe cues in the cuneus and lingual gyrus. The current study is the first to examine and compare neural activation during anticipatory anxiety in treatment-seeking individuals on topiramate and naltrexone. This preliminary research contributes to our understanding of the therapeutic mechanisms of these alcohol pharmacotherapies.

Topiramate Versus Naltrexone for Alcohol Use Disorder: A Genotype-Stratified Double-Blind Randomized Controlled Trial

OBJECTIVE

There have been no well-controlled and well-powered comparative trials of topiramate with other pharmacotherapies for alcohol use disorder (AUD), such as naltrexone. Moreover, the literature is mixed on the effects of two polymorphisms-rs2832407 (in GRIK1) and rs1799971 (in OPRM1)-on response to topiramate and naltrexone, respectively. The authors sought to examine the comparative effectiveness of topiramate and naltrexone in improving outcomes in AUD and to examine the role of the rs2832407 and rs1799971 polymorphisms, respectively, on response to these medications.

METHODS

In a 12-week, double-blind, placebo-controlled, randomized, multisite, genotype-stratified (rs2832407 and rs1799971) clinical trial comparing topiramate and naltrexone in treating AUD, 147 patients with AUD were randomly assigned to treatment with topiramate or naltrexone, stratified by genotype (rs2832407*CC and *AC/AA genotypes and rs1799971*AA and *AG/GG genotypes). The predefined primary outcome was number of heavy drinking days per week. Predefined secondary outcomes included standard drinks per drinking day per week, body mass index (BMI), craving, markers of liver injury, mood, and adverse events.

RESULTS

For the number of heavy drinking days per week, there was a near-significant time-by-treatment interaction. For the number of standard drinks per drinking day per week, there was a significant time-by-treatment interaction, which favored topiramate. There were significant time-by-treatment effects, with greater reductions observed with topiramate than naltrexone for BMI, craving, and gamma-glutamyltransferase level. Withdrawal due to side effects occurred in 8% and 5% of the topiramate and naltrexone groups, respectively. Neither polymorphism showed an effect on treatment response.

CONCLUSIONS

Topiramate is at least as effective and safe as the first-line medication, naltrexone, in reducing heavy alcohol consumption, and superior in reducing some clinical outcomes. Neither rs2832407 nor rs1799971 had effects on topiramate and naltrexone treatments, respectively.

New approved and emerging pharmacological approaches to alcohol use disorder: a review of clinical studies

introduction: The number of medications approved for AUD is small and they generally have limited efficacy. We need new pharmacotherapies for the management of AUD.Areas covered: In this review, the authors aim to synthesise literature for new approved and emerging pharmacotherapies for AUD. Recently approved medications include nalmefene, which was approved in Europe and Australia for the purposes of controlled drinking. Baclofen has also been approved in France but not in other countries. Off label medications including topiramate and gabapentin have received significant attention with multiple RCTs and meta-analyses and have widespread use in several countries including the USA. Several novel medications have emerged over the last decade but further work is required to determine their efficacy and safety for the widespread management of AUD.Expert opinion: Despite significant advances in our understanding of the neurobiological basis of factors that contribute to the development and maintenance of AUD, there have been few new AUD medications approved for almost 20 years. There are many challenges to the development and introduction of new pharmacotherapies for AUD. Strategies for improving the translational pipeline include drug repurposing and utilisation of human acute laboratory models.

Pharmacogenetics of alcohol addiction: current perspectives

Genetics of alcohol addiction is currently a contradictive and complex field, where data in the most studies reflect methods’ limitations rather than meaningful and complementary results. In our review, we focus on the genetics of alcohol addiction, leaving genetics of acute alcohol intoxication out of the scope. A review of the literature on pharmacogenetic biomarkers development for the pharmacotherapy personalization reveals that today the evidence base concerning these biomarkers is still insufficient. In particular, now the researches with the design of randomized controlled trials and meta-analysis investigating the effect of the SNPs as biomarkers on the therapy efficacy are available for naltrexone only. For other medications, there are only a few studies in small samples. It decreases the possibilities to implement the pharmacogenetic algorithms for the pharmacotherapy personalization in patients with alcohol use disorders (AUD). In view of the importance of the precision approaches development not in addiction medicine only, but in other fields of medicine also to increase the efficacy and safety of the therapy, studies on pharmacogenetic biomarkers development for the medications used in patients with AUD (eg, naltrexone, disulfiram, nalmefene, acamprosate, etc.) remain relevant to this day.

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.