Effect of Varenicline on Reactivity to Smoking and Drinking Cues

Overview

Alcohol and nicotine dependence are often co-morbid, with 85% of alcoholics also smoking. However, very little research has been conducted into the nature of this co-occurrence. Thus, the main aim of this study is to assess differences in alcohol and tobacco consumption and cue-induced craving in treatment-seeking smokers after two weeks treatment of varenicline. Hypotheses 1. Two weeks of varenicline treatment will significantly decrease cue-induced tobacco craving compared to placebo (Due to the actions of varenicline on alpha-4-beta-2 receptors and its downstream effect on dopamine release). 2. Varenicline will decrease cue-induced alcohol craving compared to placebo. 3. The impact of Varenicline on cue-induced alcohol craving will be greater in heavy drinkers compared to social drinkers.

The relationship between alcohol and tobacco dependence needs to be addressed as such populations are generally excluded from clinical trials involving smoking cessation pharmacotherapy. Furthermore, the effect of Varenicline(Pfizer Pharmaceuticals)treatment on tobacco cue-induced craving has not been empirically measured, nor has the effect of varenicline on alcohol consumption. In addition to being an effective aid in smoking cessation, preliminary evidence has shown that Varenicline can decrease alcohol consumption in animal models. Varenicline is a partial agonist of the α4β2 nicotinic acetylcholine receptor. This drug's partial agonist effect allows for the activation of this receptor at a lesser degree than nicotine while simultaneously preventing nicotine binding due to the drugs high affinity (i.e.: antagonist effect) for this receptor subtype. Varenicline has recently been approved in Canada as an aid for smoking cessation. This study will be a double-blind, placebo-controlled randomized study. It will assess differences in alcohol and tobacco consumption and cue-induced craving in treatment-seeking smokers after two weeks of treatment with either varenicline or placebo.Ultimately This study may help to further understand the association between smoking and drinking alcohol. This study will consist of two study groups composed of 40 subjects each being randomized to receive either placebo or varenicline (0.5mg once daily for days 1-3, 0.5mg twice daily for days 4-7 followed by 1mg twice daily for days 8-14). One group will be heavy smokers and heavy drinkers while the other will be heavy smokers and social drinkers. Upon entering the study, subjects will undergo baseline cognitive and craving measures for both tobacco and alcohol associated cue presentations prior to randomization to varenicline or placebo. Subjects will be provided a 1-week supply of study medications and directions for use. During this period, subjects will be requested to complete a diary outlining their cigarette and alcohol craving and consumption each day and outline any adverse effects. Upon completion of this 1-week period, subjects will attend the Centre for Addiction and Mental Health (CAMH) where their old pill bottles and daily diaries will be collected and they will be supplied with study medication (1mg varenicline taken twice daily or placebo) and daily diary for an additional week. At this visit, subjects will complete the symptom checklist. At the end of the second week of treatment, subjects will be requested to return to CAMH where craving for tobacco and alcohol and cue-reactivity will be assessed in a similar manner as to study day After study completion, all subjects will be given the option to continue with varenicline in a 12-week treatment plan through the Nicotine Dependence Clinic.