A randomized, double-blind, placebo-controlled, multicentre trial on the efficacy of varenicline and bupropion in combination and alone for treatment of alcohol use disorder: Protocol for the COMB study.

backgroundAlcohol Use Disorder (AUD) is a major cause of premature death, disability and suffering. Available treatments are of modest efficacy and under-prescribed so there is a pressing need for a well-tolerated and effective treatment option for AUD. Dopamine is hypothesized to be involved in the development of alcohol dependence. To challenge the low-dopamine hypothesis of addiction, this randomized, double-blind, placebo-controlled, 13-week, multicentre clinical trial with four parallel arms is designed to evaluate the efficacy of two substances raising dopamine levels, varenicline and bupropion, alone and in combination vs. placebo on alcohol consumption in AUD. Varenicline, a partial agonist at brain nicotinic acetylcholine receptors increases dopamine release, whereas bupropion is a centrally-acting, norepinephrine-dopamine reuptake inhibitor. Varenicline is previously shown to reduce alcohol intake in individuals with AUD. We hypothesize that the effect size of a combination of two drugs affecting dopamine levels in the brain will exceed that of approved AUD therapies.

methodsConsenting individuals with AUD will be recruited via media advertisements. Those fulfilling the eligibility criteria (N = 380) will be randomized to one of four interventions (n = 95 per arm). Treatment will comprise one week of titration (varenicline 0.5‒2 mg; bupropion SR 150‒300 mg) plus 12 weeks at steady state. Efficacy will be evaluated using two primary endpoints of alcohol consumption: Heavy Drinking Days and blood levels of phosphatidylethanol. Secondary objectives, exploratory and subgroup analyses will be also performed. The modified Intention-to-Treat and Per Protocol datasets will be evaluated using Analysis of Covariance. Last patient out is estimated to occur in December, 2022. DISCUSSION: The COMB Study aims to evaluate the efficacy of the combination of varenicline and bupropion, two drugs affecting dopamine, on alcohol consumption, and to challenge the low-dopamine hypothesis of addiction. Study Code COMB-BO8, EudraCT 2018-000048-24, Version 3.2, Lidö & deBejczy, 2020-06-16; https://clinicaltrials.gov identifier NCT04167306.