Nicotine levels, withdrawal symptoms, and smoking reduction success in real world use: A comparison of cigarette smokers and dual users of both cigarettes and E-cigarettes.
INTRODUCTION
To evaluate how experienced dual users used cigarettes and e-cigarettes in real-world use and under different levels of cigarette availability.


METHODS
Dual users (cigarettes+e-cigarettes; n=74) and a smoke-only group (just cigarettes; n=74) engaged in a 26-day study with two ad lib use intervals, a week of 75% cigarette reduction and three days of 100% cigarette reduction. After a week of ad lib use of products, all participants were asked to reduce smoking by 75% (dual users were free to use their e-cigarettes as they wished), followed by another week of ad lib use. All participants were then asked to reduce smoking by 100% (cessation) for three days. Primary outcomes were biological samples (carbon monoxide, urinary nicotine and cotinine). Participants also provided real-time reports of product use, craving, and withdrawal symptoms using a smartphone app.


RESULTS
Dual users did not smoke fewer cigarettes than smoke-only participants during ad lib periods, but quadrupled their use of e-cigarettes during smoking reduction periods. Dual users were significantly more likely to maintain 100% reduction (97.1% vs. 81.2%). Amongst women, dual use was associated with higher nicotine levels and withdrawal suppression.


DISCUSSION
Among a group of experienced dual users, e-cigarettes helped maintain smoking reduction and reduced some withdrawal symptoms, although both withdrawal symptoms and nicotine levels varied as a function of gender.
['Jorenby|Douglas E|DE|', 'Smith|Stevens S|SS|', 'Fiore|Michael C|MC|', 'Baker|Timothy B|TB|']
D000328:Adult D066249:Craving D066300:Electronic Nicotine Delivery Systems D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D009538:Nicotine D012907:Smoking D016540:Smoking Cessation D013375:Substance Withdrawal Syndrome D062789:Tobacco Products D014029:Tobacco Use Disorder D055815:Young Adult
Nicotine e-cigarettes Dual use Cigarette smoking Gender differences Nicotine dependence