Acetylcysteine for Smoking Cessation in Cigarette-Cannabis Co-users

Inclusion Criteria

• Male and female smokers ages 18 and over
• Have smoked 5 cigarettes per day in 15 of the past 30 days, or an average of 2.5 cigarettes per day for the past 30 days
• Endorse the use of cannabis within the past 30 days, reported by timeline follow-back (TLFB) and have positive urine tetrahydrocannabinol (THC) at week 0
• Meet criteria for tobacco use disorder (TUD) in the past 12 months per Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), assessed by the Mini International Neuropsychiatric Interview (MINI), medical record review, and clinical assessment
• Consent to receive interventions to stop smoking cigarettes and using cannabis. Although co-users can use tobacco and cannabis simultaneously (i.e. in “spliffs”) and other forms of nicotine and tobacco, participants must smoke combustible cigarettes that are not mixed with cannabis on a daily basis to participate
• Women of childbearing potential (ages 18-55) must have a negative urine pregnancy test at the time of screening
• Individuals who are prescribed bupropion for depression, not smoking cessation, are eligible to participate in this study
• All participants must be California residents (Veterans enrolled in Veterans administration [VA] healthcare in another state are eligible)

Exclusion Criteria

• Psychotic disorders, bipolar disorder, neurocognitive disorder, or other psychiatric or medical conditions judged by the principal investigator (PI) to be unstable in the past 30 days, based on MINI
• Concurrent participation in another addiction treatment study or pharmacological study
• Females who are pregnant or lactating
• Non-study NAC use at enrollment or at any time during the study period
• Use of medications for TUD (nicotine replacement therapy [NRT], bupropion, or varenicline) at enrollment or at any time during the study period
• A suicide attempt or suicidal ideation with intent in the 30 days prior to enrollment
• Non-residents of California or Veterans in another state who are not enrolled in VA healthcare