PURPOSE: The purpose of this placebo controlled study is to determine the efficacy, safety, and gender differences in using varenicline for smoking cessation in a population of stable methadone maintenance patients being treated for Opioid Dependence.~HYPOTHESIS:~1.Stable methadone maintenance patients receiving varenicline will be more likely to maintain abstinence than patients receiving placebo 2.There will be no differences in the type and number of symptoms reported between stable methadone maintenance patients receiving varenicline and placebo 3.There will be no changes in methadone dosage between abstinent and non-abstinent smokers 4.There will be no differences in efficacy, withdrawal symptoms, and safety of varenicline between male and female participants~3. JUSTIFICATION: Patients on methadone maintenance treatment have smoking prevalence rates of up 80-90% and consequently disproportionately high mortality compared to the general population. A majority of these patients express a desire to quit but are generally more heavily dependent on nicotine. Randomized controlled trials in non-drug using populations have shown varenicline to be more efficacious for smoking cessation than placebo and other smoking cessation medications. This placebo controlled research protocol will examine varenicline's effect on smoking cessation/reduction and potential sex and gender differences in a population of methadone maintained patients.~4. OBJECTIVES:~Primary outcome:~Continuous abstinence from smoking during the last 4 weeks of treatment (weeks 9-12).~Secondary outcomes:~7-day point prevalence of abstinence~Continuous abstinence Weeks 9-26~Sex and gender differences~Psychological assessment (Beck Depression Inventory)~Adverse effects (Nausea, Dry mouth, Flatulence, Constipation, Insomnia, -Abnormal dreams, Irritability, Sleep disorder, Headaches, Dizziness e.t.c.)~5. RESEARCH METHOD: This pilot randomized, double-blind, placebo-controlled trial will be conducted at Vancouver Coastal Health Tobacco Dependence Clinic Vancouver, BC with a 12-week treatment period and follow-up of smoking status to week 26. The intervention will include the use of Varenicline titrated to 1 mg twice daily or placebo for 12 weeks, plus weekly brief smoking cessation counseling.~6. All significance tests will be 2-tailed with an overall level of significance of a = 0.05. The primary outcome will be the analysis of continuous abstinence using a logistic regression model. The secondary outcomes will be:~the analysis of 7-day abstinence and 9-26 week continuous abstinence using logistic regression analysis.~Minnesota Nicotine Withdrawal Scale, Beck's Depression Inventory, and changes in methadone dose outcome using repeated measures analysis, and~Chi-square tests and t-tests (or Mann-Whitney U) to determine sex and gender differences (male vs female) as well as differences in adverse effects of treatment (varenicline vs placebo)
The main hypotheses guiding the study are:~Stable methadone maintenance patients receiving varenicline will be more likely to maintain abstinence than patients receiving placebo~There will be no differences in the type and number of symptoms reported between stable methadone maintenance patients receiving varenicline and placebo~There will be no changes in methadone dosage between abstinent and non-abstinent smokers~There will be no differences in efficacy, withdrawal symptoms, and safety of varenicline between male and female participants