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Updated: Feb 26, 2026

Comparing the Effects of Electronic Cigarette Vapor and Cigarette Smoke in a Novel In Vivo Exposure System
Published on: May 24, 2017
Impact of e-liquid flavors on nicotine intake and pharmacology of e-cigarettes
Gideon St Helen1, Delia A Dempsey2, Christopher M Havel2
1Division of Clinical Pharmacology and Experimental Therapeutics, Department of Medicine, University of California, San Francisco, CA, USA; Center for Tobacco Control Research and Education, University of California, San Francisco, CA, USA; Tobacco Center of Regulatory Science (TCORS), University of California, San Francisco, CA, USA.
Objectives:
To describe the effect of e-liquid flavors on nicotine intake and pharmacology of e-cigarettes.
Methods:
11 males and 3 females participated in a 3-day inpatient crossover study with strawberry, tobacco, and their usual flavor e-liquid. Nicotine levels were nominally 18mg/mL in the strawberry (pH 8.29) and tobacco (pH 9.10) e-liquids and ranged between 3-18mg/mL in the usual brands (mean pH 6.80). Each day consisted of a 15-puff session followed by 4h of abstinence, then 90min of ad libitum use. Subjects used a KangerTech mini ProTank 3.
Results:
After 15 puffs, the amount of nicotine inhaled and systemically retained were not significantly different between the strawberry and tobacco e-liquids but plasma AUC(0→180) was significantly higher with the strawberry e-liquid. While not significantly different, Cmax was 22% higher and various early time point AUCs to measure rate of rise of nicotine in blood ranged between 17 and 23% higher with the strawberry e-liquid compared to the tobacco e-liquid. During ad libitum use, systemic exposure to nicotine (AUC(0→90)) was the same for the tobacco and usual brand e-liquids but were both significantly lower than after using the strawberry e-liquid. The usual flavors were more liked and satisfying than the strawberry and tobacco e-liquids.
Conclusion:
Flavors influence nicotine exposure through flavor liking, may affect rate of nicotine absorption possibly through pH effects, and contribute to heart rate acceleration and subjective effects of e-cigarettes. E-cigarette users titrate their nicotine exposure but the extent of titration may vary across flavors.
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