Changes in Nicotine Dependence Among Smokers Using Electronic Cigarettes to Reduce Cigarette Smoking in a Randomized Controlled Trial.

INTRODUCTION: How nicotine dependence will be affected when current smokers initiate electronic cigarette (e-cigarette) use to reduce cigarette smoking is unknown. This study evaluated cigarette, e-cigarette, and total nicotine dependence more than 6 months among smokers reducing cigarette consumption by replacing with e-cigarettes. AIMS AND METHODS: Adult cigarette smokers were randomized to one of four conditions (36 mg/ml e-cigarette, 8 mg/ml e-cigarette, 0 mg/ml e-cigarette, or cigarette-substitute [CS] [provided at no cost]) and instructed to reduce their cigarette smoking by 75% at 1 month. Participants completed follow-up at 1, 3, and 6 months. The Penn State Nicotine Dependence Index (PSNDI) measured dependence on cigarettes (PSCDI) and e-cigarettes (PSECDI). Urine cotinine measured total nicotine exposure. Linear mixed effects models for each outcome were conducted and included interaction terms between visit and condition. RESULTS: Participants (n = 520) were 58.8% female, 67.3% White, and 48.0 years old. At baseline, the median number of cigarettes smoked per day was 17.3 and the mean PSCDI score was 13.4, with no significant differences between conditions. Participants in the e-cigarette conditions reported significantly lower PSCDI scores, compared with baseline, and with the CS condition at all follow-up visits. Those in the 36 mg/ml e-cigarette condition reported greater PSECDI scores at 6 months, compared with baseline and the 0 mg/ml and 8 mg/ml conditions. At all follow-up visits, there were no differences in total nicotine exposure compared to baseline, nor between any conditions. CONCLUSIONS: E-cigarette use was associated with reduced cigarette dependence, compared to the CS, without significant increases in total nicotine exposure. IMPLICATIONS: Initiation of electronic cigarette use while continuing to smoke could potentially increase nicotine dependence. In this randomized trial aimed at helping smokers to reduce their cigarette intake, we found that use of an e-cigarette was associated with a reduction in cigarette dependence and an increase in e-cigarette dependence (in the condition with the highest nicotine concentration only), with no long term increase in total nicotine dependence or nicotine exposure.

E-cigarette Solvent Ratio and Device Power Influence Ambient Air Particulate Matter.

OBJECTIVES: Electronic cigarette (ECIG)-generated aerosol contains particulate matter with a diameter less than 2.5 microns (PM2.5). Particles of this size may be injurious to the health of those who inhale them. Few studies have assessed the relationship between ECIG aerosol PM2.5 and ECIG liquid ingredients or ECIG device power. METHODS: Two studies were conducted in which participants generated aerosols with ECIGs: in one, ECIG liquids contained various vegetable glycerin/propylene glycol ratios and in the other, ECIG devices varied by electrical power output. RESULTS: Results indicate that, in general, PM2.5 increases as the ratio of vegetable glycerin to propylene glycol increases, or as device power increases. CONCLUSIONS: Regulating ECIG PM2.5 emissions to protect non-users requires an understanding of all the factors that influence these emissions.

Acute effects of JUUL and IQOS in cigarette smokers.

BACKGROUND: JUUL is an electronic cigarette that aerosolises a nicotine-containing liquid, while IQOS heats tobacco to produce an aerosol. Both are marketed to smokers, but their effects have seldom been examined in this population. METHODS: Eighteen cigarette smokers (13 men) with no JUUL or IQOS experience completed a within-subject, laboratory study assessing nicotine delivery and subjective effects after controlled (10 puffs, ~30 s interpuff interval) and ad libitum (90 min) use of JUUL, IQOS or own-brand (OB) cigarettes. RESULTS: JUUL increased mean plasma nicotine concentration significantly from 2.2 (SD=0.7) ng/mL to 9.8 (4.9) ng/mL after 10 puffs and to 11.5 (9.3) ng/mL after ad libitum use. IQOS increased mean plasma nicotine significantly from 2.1 (0.2) ng/mL to 12.7 (6.2) ng/mL after 10 puffs and to 11.3 (8.0) ng/mL after ad libitum use. OB increased mean plasma nicotine significantly from 2.1 (0.2) ng/mL to 20.4 (11.4) ng/mL after 10 puffs and to 21.0 (10.2) ng/mL after ad libitum use. Mean OB plasma nicotine concentration was significantly higher than JUUL and IQOS. OB increased expired carbon monoxide concentration, but IQOS and JUUL did not. 'Craving a cigarette/nicotine' and 'Urges to smoke' were reduced significantly for all products following the directed bout. CONCLUSIONS: Among smokers, JUUL and IQOS delivered less nicotine than cigarettes. Also, in this sample, IQOS and OB reduced abstinence symptoms more effectively than JUUL. Additional work with experienced JUUL and IQOS users is needed, as their nicotine delivery profiles and subjective experiences may differ.