There is a marked prevalence of tobacco use and tobacco-related disease among methadone maintenance patients. Varenicline's demonstrated efficacy may not be generalizable to methadone maintained smokers because of poor adherence, which is highly prevalent among drug users. Adherence to smoking cessation medication is strongly associated with cessation, and is one of the few factors shown to increase cessation among methadone maintained smokers, but strategies to promote smoking cessation medication adherence have not been evaluated in methadone patients. Based on the Information, Motivation, and Behavior model, the investigators plan a directly observed therapy (DOT)-based intervention targeting behavioral skills necessary for optimal adherence. Because methadone clinic-based DOT interventions have been shown to improve medication adherence and clinical outcomes in HIV and TB, the investigators plan to determine in a randomized trial whether DOT varenicline provided at a methadone clinic is more efficacious than self-administered varenicline for promoting smoking cessation and enhancing adherence. The investigators will also evaluate moderating effects of drug and alcohol use and psychiatric symptoms on DOT effects. The investigators hypothesize subjects in the mDOT arm will have greater 7 day point prevalence abstinence at 12 weeks, reduction in cigarettes/day, time to first daily cigarette, ≥ 24 hour quit attempts, and 7 day point prevalence abstinence at 24 weeks compared to subjects receiving self administered varenicline. The investigators also hypothesize that adherence in the mDOT arm will be higher than in the TAU arm. Lastly the investigators hypothesize that ongoing illicit drug use and psychiatric symptoms will moderate the effect of mDOT on adherence.
This randomized trial will evaluate whether varenicline directly observed therapy provided at a methadone clinic is more efficacious than self-administered varenicline for promoting smoking cessation and enhancing adherence.