Cannabis-Tobacco Co-Use Treatment Study

Tobacco-cannabis co-use results in established harms, yet there are currently no recommended treatment strategies for co-use. The scientific premise of this proposal is based on work conducted by our group demonstrating that: 1) cannabis co-use adversely impacts cigarette abstinence and those co-using cannabis have nearly double the odds of tobacco treatment failure, 2) varenicline may be efficacious in treating CUD, and 3) cannabis reduction (vs. abstinence) may be a potentially more appealing treatment goal. Therefore, this project proposes to evaluate varenicline versus placebo on cigarette abstinence and cannabis use reduction or abstinence among adults who co-use. To bolster outcomes, both groups will receive an evidence-based psychosocial intervention that includes real-time and asynchronously delivered content (all delivered virtually), that leverages the co-use intervention used by Budney (Consultant) as well brief weekly counseling and check-in sessions that we have used in previous and ongoing studies. Asynchronous content (web-based modules) is standardized and through a tailored approach to counseling, the intervention will allow for participant preference for cannabis reduction or abstinence. The selection of this combination treatment for tobacco-cannabis co-use is based on rigorous prior research demonstrating: 1) efficacy of varenicline for tobacco cessation, 2) preliminary efficacy of varenicline for cannabis use, and 3) acceptable, psychosocial co-use treatment modules that have the potential to augment a robust pharmacotherapy to improve outcomes.

Investigators propose a completely remote 12-week treatment trial among adults in South Carolina (ages 18+; N=200) who co-use cigarettes and cannabis regularly. Participants will be included who smoke cigarettes daily or near daily (20+ days in the past 30) and have used cannabis at least 3 times per week in the past month. Participants will be randomized 1:1 to varenicline or placebo and all participants will receive the platform psychosocial intervention. The aims of the study are to: 1) evaluate rates of 7-day biochemically confirmed point prevalence abstinence (PPA) from cigarettes at the 12-week EOT visit comparing varenicline + psychosocial intervention to the placebo + psychosocial intervention participants (Aim 1), 2) compare cannabis use frequency and amount between varenicline and placebo groups during treatment (Weeks 1-12; Aim 2), and 3) explore differential treatment outcomes among male vs. female participants (Exploratory Aim).

Inclusion criteria

• Ages 18 and over (no upper age limit)
• Must smoke at least 5 tobacco cigarettes per day on at least 20 out of the past 30 days for the past 3 months
• Must express interest in quitting tobacco
• Must express interest in cannabis reduction and/or cessation
• Must submit a positive instant-read test for cotinine and cannabis prior to enrollment
• Must self-report cannabis use (THC-dominant products) on at 3 days per week out of the past 30 days
• Must be willing to take varenicline or placebo for 12 weeks
• Must reside in South Carolina

Exclusion criteria

• Any significant or acutely unstable medical, psychiatric, or substance use problem (including clinically significant disorders) that would contraindicate research, interfere with safety, compromise data integrity, or preclude consistent study participation
• Pregnant or trying to become pregnant
• Use of medications with smoking cessation efficacy
• Regular use of e-cigarettes or other tobacco products (<10 days in the past month)