Three hundred-twenty (320) adult smokers of menthol or non-menthol combustible cigarettes will be recruited and randomly assigned to one of five groups (n=64/group), who will be asked to switch for 12 weeks to ad libitum use of combustible cigarettes (matched to subjects' menthol preference) containing either 0.4, 1.4, 2.5, 5.6 or 16.9 mg nicotine (standardized nicotine yields ranging from 0.02-0.80 mg/cigarette), respectively. Each group will include 32 heavy (≥ 20 cigarettes/day), and 32 light smokers (≤10 cigarettes/day), who are hypothesized to be more sensitive to nicotine's reinforcing effects. Participants will also have free access to nicotine-containing e-cigarettes (JUUL) throughout the 12-week period. Abuse liability of combustible cigarettes will be assessed by behavioral (cigarettes/day, time to first cigarettes), self-report (rewarding effects, withdrawal symptoms) and biochemical indices (expired air carbon monoxide, cotinine blood sampling). In laboratory sessions, we will measure nicotine thresholds for detecting and recognizing the addictive, rewarding effects of smoking. This study is designed to help the FDA identify a target nicotine threshold that will not attract young people to smoking or induce relapse in former smokers. Additionally, we will determine the level of cigarette nicotine reduction that will be tolerated without inducing dissatisfaction in smokers, information that is relevant to the FDA for designing a stepwise nicotine reduction policy that can be implemented without widespread objections. The knowledge gained from this project will greatly increase our knowledge of nicotine addiction and will help frame an FDA policy relating to the regulation of the nicotine content of tobacco. Ultimately, a well-designed nicotine reduction policy has the potential to greatly reduce the enormous toll of death and disease caused by cigarette smoking.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
150
Smoking research cigarettes with varying levels of nicotine with unlimited access to 15 mg/ml nicotine-containing e-cigarettes.
Measure of nicotine thresholds for detecting and recognizing the addictive, rewarding effects of smoking.
Rose Research Center
Charlotte, North Carolina, United States
Rose Research Center
Raleigh, North Carolina, United States
Expired air CO Measurement
To determine the effects of cigarette nicotine content manipulations on abuse liability as measured by exhaled breath CO.
Time frame: 12 Weeks
Nicotine discrimination tests to determine nicotine detection thresholds
Results of the laboratory discrimination tests will be analyzed descriptively to determine nicotine detection thresholds. Thresholds will be calculated based on both group-averaged data as well as by using the best estimates of individual thresholds calculated from each smoker's data. Group averaged data will be determined by graphically plotting the overall percent correct against nicotine concentration.
Time frame: Weeks 1, 2,8,10,12 and 14
Nicotine discrimination tests to determine nicotine recognition thresholds
Results of the laboratory discrimination tests will be analyzed descriptively to determine nicotine recognition thresholds. Thresholds will be calculated based on both group-averaged data as well as by using the best estimates of individual thresholds calculated from each smoker's data. Group averaged data will be determined by graphically plotting the overall percent correct against nicotine concentration.
Time frame: Weeks 1, 2,8,10,12 and 14
Extent of e-cigarette use based on self-report
To determine whether the abuse liability of combustible cigarettes is related to the nicotine intake from e-cigarettes or to total nicotine intake, regression analyses will be conducted to correlate indices of abuse liability to levels of cotinine as well as to the estimated intake of nicotine from cigarettes and e-cigarettes based on self-reported values.
Time frame: 12 Weeks
Extent of e-cigarette use based on self-report cotinine levels
To determine whether the abuse liability of combustible cigarettes is related to the nicotine intake from e-cigarettes or to total nicotine intake, regression analyses will be conducted to correlate indices of abuse liability to levels of cotinine as well as to the estimated intake of nicotine from cigarettes and e-cigarettes.
Time frame: 12 Weeks
Mean number of research cigarettes smoked per day as primary index of abuse liability
To assess the effects of cigarette nicotine content on abuse liability among smokers who also use e-cigarettes. The primary index of abuse liability will be mean number of research cigarettes smoked per day. Secondary outcome measures comprise expired air carbon monoxide (CO), Fagerström Test for Nicotine Dependence (FTND) score, withdrawal symptoms and cognitive performance.
Time frame: 12 Weeks
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