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

Abstract

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 (Cmax) 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 Cmax (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 (Tmax). 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.

Trial registration: ClinicalTrials.gov Identifier: #NCT02575885.

Keywords: E-cigarettes; Electronic cigarettes; Flavors; Nicotine; Vaping; Vaporizers.

Conflict of interest statement

Conflicts of Interest: MLG has received research grant support from Pfizer and served as a member of the advisory board of Johnson & Johnson. MCM is on the speakers bureau, has served as a consultant to, and has received research support from Pfizer. NLB is a consultant to Pfizer and Achieve Life Sciences and has been a paid expert witness in litigation against tobacco companies. Other authors have no conflicts to declare.

Figures

Figure 1.

Participant flow chart.

Figure 2.

Changes in plasma nicotine concentration after use of different flavored e-cigarette (nominally 24 mg/ml nicotine concentration) compared to preferred brand tobacco cigarette.

Figure 3.

Subjective rating of various flavors: (A) Satisfaction with flavors. (B) Enjoyment from using different flavors. (C) Perceived harm of flavors (Left bar indicates average for participants who do not use a mentholated combustible cigarette, right bar indicates average for participants who do use a mentholated combustible cigarette. (D) Taste of different flavor. (E) Difficulty puffing on different flavors. *Horizontal bars indicate significant differences between flavors (p<.05 taken from pairwise comparisons when controlling for c>max)