Objective:
Considerable clinical and experimental evidence in humans and animal models links nicotine use with heavy alcohol consumption. Varenicline, an alpha4beta2 (nicotinic) acetylcholine receptor (nAchR) partial agonist, is an oral medication approved by the FDA (2006) for smoking cessation. Recently, it has been shown to reduce alcohol consumption in a rodent model of alcohol dependence. In the present short-term experimental study, it will be assessed primarily for its ability to reduce alcohol self-administration in heavy drinkers. Secondarily, its effects on alcohol urges (cravings), as well as smoking parameters will be measured. In addition, effects of varenicline on incentive motivation for alcohol and the underlying brain reward system activation, as well as on activation of brain reward systems in response to intravenously administered alcohol will be measured.
Study Population:
Fifty healthy, adults (smokers and non-smokers), age 21 to 60 years, will be studied. Individuals must drink alcohol regularly at a heavy level, on average greater than 20 drinks per week for men, and greater than 15 drinks per week for women, and not be seeking help for alcohol-related problems.
Design:
Following protocol screening and medical evaluation, qualified subjects will undergo an initial ( pre-study drug ) intravenous alcohol self-administration session (hereafter, called computer-assisted self-infusion of ethanol, or CASE). Following this, subjects will be randomized to varenicline or placebo. Subjects will be clinically evaluated on three occasions while on study drug: once after one week of study medication; again, prior to the fMRI; and again, at the end of treatment, when they undergo the second ( on-study drug ) CASE session. Between days 13 and 21, all subjects will be scheduled to undergo functional magnetic resonance imaging (fMRI) of the brain while performing a task designed to evaluate the incentive salience for alcohol cues as well as the pharmacological effects of alcohol. Thereafter, all subjects will receive two courses of counseling for heavy drinking, using motivational enhancement techniques, aimed at enhancing their readiness for behavioral change and seeking treatment, if needed.
Outcome Measures:
The primary outcome will be the peak breath alcohol exposure achieved during the on-study drug CASE session. Secondary outcomes during the study drug phase will include measures of alcohol consumption, and urges to drink, as well as alcohol cravings and effects during the on-study drug CASE session. Additionally, fMRI BOLD responses in the ventral striatum, an area involved in brain reward circuitry and shown to be activated by acute IV alcohol administration as well as anticipation of working for reward will be measured. In smokers, cigarette use and quite rates as well as urges to smoke and nicotine withdrawal will also be measured. Safety and tolerability will be followed during the course of taking study drug with symptom checklists, profiles of mood and anxiety and by clinical interview. Serum varenicline concentrations will also be measured to assess compliance and control for potential pharmacokinetic variation.
