NCT04092101.

Study name	Low nicotine content cigarettes in vulnerable populations: opioid use disorder
Methods	RCT Recruitment: Daily smokers who are receiving methadone or buprenorphine treatment will be recruited at University of Vermont and Johns Hopkins University. Setting: University of Vermont and Johns Hopkins University, USA
Participants	Estimated enrolment: 310 Inclusion criteria: Maintained on opioid medication 21 to 70 years old
Interventions	EC: type not specified, 'normal nicotine content cigarette and ... a reduced nicotine content cigarette' Cigarettes with varying nicotine content E‐Cigarettes Arm 1 Cigarettes with varying nicotine content. Altering the nicotine content of the tobacco research cigarette. Research Cigarettes #1 Arm 2: Cigarettes with varying nicotine content. Altering the nicotine content of the tobacco research cigarette. Research Cigarettes #2. Arm 3: Cigarettes with varying nicotine content. Altering the nicotine content of the tobacco research cigarette. E‐Cigarettes. 1) Altering the availability of e‐cigarettes; 2) Altering option to personalize the e‐liquid in the e‐cig condition Research Cigarettes #2 plus E‐cigarettes #1 Arm 4: Cigarettes with varying nicotine content. Altering the nicotine content of the tobacco research cigarette E‐Cigarettes. 1) Altering the availability of e‐cigarettes; 2) Altering option to personalize the e‐liquid in the e‐cig condition. Research Cigarettes #2 plus E‐cigarettes #2
Outcomes	16 weeks Outcome measures include total cpd, cigarette demand assessed by behavioural economics‐based purchase tasks, craving, withdrawal, psychiatric symptoms, breath carbon monoxide (CO), biomarkers of tobacco toxicant exposure, brain function and structure, and airway inflammation (fractional nitric oxide concentration in exhaled breath [FeNO])
Starting date	Start date: September 24 2019. Estimated completion date: July 2023
Contact information	Shirley Plucinski 9788752361, shirley.plucinski@uvm.edu
Notes	New to 2022 update