Effect of e-cigarette flavors on nicotine delivery and puffing topography: results from a randomized clinical trial of daily smokers

Rationale There is limited understanding regarding how various e-cigarette flavorings may influence the behavior of non-regular e-cigarette users who are regular cigarette smokers. Objectives To assess differences in nicotine delivery, puffing topography, subjective effects, and user satisfaction from different flavored e-liquids. Methods Eighteen daily smokers (average age, 44.1 +/- 7.0; 9 males; average CPD, 13.0 +/- 5.8) smoked their tobacco cigarettes during an initial visit and returned five times to try an e-cigarette (eGo type) refilled with a nicotine solution (24 mg/ml) of five different flavors: cherry, tobacco, espresso, menthol, and vanilla (randomized order). Assessments at each visit included puffing topography, blood samples for nicotine analysis, and subjective reports of nicotine effects and flavor satisfaction. Results Vaping different flavors resulted in different levels of plasma nicotine. The flavor producing the highest plasma nicotine concentration (C-max) was cherry (median 21.2 ng/ml), which was not significantly different than nicotine delivery from a combustible cigarette (29.2 ng/ml, p > .05). Vanilla e-liquid produced the lowest C-max (9.7 ng/ml), and participants tended to puff less frequently on vanilla compared to tobacco flavor (p = .013). Flavors did not differ significantly in the speed of nicotine delivery (T-max). During controlled use, puff duration for all flavors was significantly longer than a combustible cigarette (p < 0.05). After controlling for nicotine delivery, significant differences in flavor enjoyment were detected. Menthol flavored e-liquid was rated as more enjoyable than vanilla and tobacco flavored e-liquids (p < 0.05). Conclusions Flavors tested in this study yielded different patterns of nicotine delivery and led to differences in reduction in smoking urges.