Differences in nicotine intake and effects from electronic and combustible cigarettes among dual users

Abstract

Aim: To describe systemic nicotine exposure and subjective effects of electronic cigarettes (e-cigarettes) in people who use both e-cigarettes and cigarettes (dual users), including within-subject comparisons of e-cigarette and cigarette use.

Design: Two-arm, counterbalanced cross-over study. Participants used their usual brand of e-cigarette or cigarette during a standardized session in a 2-week study.

Setting: Hospital research ward, San Francisco, CA, USA.

Participants: Thirty-six healthy (eight women, 28 men) participants.

Measurements: Plasma nicotine was analyzed by gas chromatography-tandem mass spectrometry; nicotine withdrawal, urge to smoke and vape, affective states, craving, satisfaction and psychological reward were measured by standardized questionnaires.

Findings: Compared with cigarettes, average maximum plasma nicotine concentration (C_max ) was lower with e-cigarettes [6.1 ± 5.5 ng/ml, mean ± standard deviation (SD) versus 20.2 ± 11.1 ng/ml, P < 0.001] and time of maximal concentration (T_max ) was longer (6.5 ± 5.4 versus 2.7 ± 2.4 minutes, P < 0.001). Use of both products resulted in a reduction in the severity of withdrawal symptoms, negative affect and urge to use either product. E-cigarettes were less rewarding and satisfying and reduced craving to a lesser degree than cigarettes. We were not able to detect any differences in withdrawal symptoms, affective states and urge to smoke cigarettes between e-cigarette and cigarette use.

Conclusion: Systemic nicotine exposure was, on average, lower with single use of e-cigarettes compared with cigarettes, and e-cigarettes were judged to be less satisfying and rewarding and reduced craving less than cigarettes.

Keywords: Dual users; JUUL PK profile; e-cigarette dependence; e-cigarettes; nicotine pharmacokinetics; subjective effects.

FIGURE 1

Average plasma nicotine concentration profile for electronic cigarettes and combustible cigarettes of all participants (A); within subject maximum plasma nicotine concentration (C_max) when using electronic and combustible cigarettes (B); and, average plasma nicotine concentration profile for the main types of electronic cigarettes included in the study (C). Plot A, blood nicotine levels were significantly different between e-cigarettes and cigarettes at all time points. Plot B, solid black lines = cig-a-likes; solid grey line = fixed-power tanks and broken black line = variable-power tanks. Plot C, blood nicotine levels were significantly different between variable-power tanks and fixed-power tanks.

FIGURE 2

Average plasma nicotine concentration profile for electronic cigarettes and combustible cigarettes for users of cig-a-likes (A), fixed-power tanks (B), and variable-power tanks (C). The plasma nicotine concentration profiles of the three pod users are given in plots D-F. Plots A-C: Blood nicotine levels were significantly different between e-cigarettes and cigarettes.

FIGURE 3

Changes in nicotine withdrawal (Minnesota Nicotine Withdrawal Scale, MNWS total score) (A), negative affect (Positive and Negative Affect Schedule, PANAS Negative subscale score) (B), urge to vape (Questionnaire for Smoking Urges-Brief, QSU Factor 1 and Factor 2 for vaping) (C, D), and urge to smoke cigarettes (QSU Factor 1 and Factor 2 for smoking) (E, F) before and after electronic and combustible cigarette use. The product assignment × time interaction term was not statistically significant for any of the measures. Open markers indicate significant difference from baseline and * indicates significant difference between e-cigarettes and combustible cigarettes.