Nicotine delivery and users' reactions to Juul compared with cigarettes and other e-cigarette products

Aims: To assess the pharmacokinetic (PK) profile of, and users' reactions to, Juul (59 mg nicotine/ml) as an indication of its therapeutic and dependence potential.

Design: Cross-over, within-subjects study in which participants attended after overnight abstinence on separate sessions and smoked a cigarette or used Juul or eight other types of e-cigarettes (EC) ad libitum for 5 minutes. The Juul product used was the version available in the United States that has more nicotine in the e-liquid than the one available in the European Union.

Setting: Laboratory setting in the United Kingdom.

Participants: Twenty dual users (smokers who also vape) provided data on Juul and cigarettes, with eight also providing data on other EC products.

Measurements: At each session, number of puffs taken was counted during the 5-minute product use period and blood samples were taken at baseline and at 2, 4, 6, 8, 10 and 30 minutes after starting smoking/vaping and analysed for nicotine. Participants also monitored their urges to smoke and rated the products on a range of characteristics.

Findings: Juul's PK profile was close to the PK profile of cigarettes [maximum concentration (C_max ) = 20.4 versus 19.2 ng/ml; time to maximum concentration (T_max ) = 4 versus 6 minutes; area under the curve (AUC): 307.9 versus 312.6, respectively]. Compared with other EC products, Juul had shorter T_max [4 minutes, (IQR = 2.5-4.0) versus 6.3 minutes, (IQR = 4.7 - 8.1), P = 0.012] and higher C_max (28.9 (SD = 15.6) versus 10.6 (SD = 5.5), P = 0.013) despite a lower number of puffs (12.5 (SD = 4.2) versus 17.0 (SD = 4.2), P = 0.084). Compared with other e-cigarette products, it also provided faster reduction of urges to smoke and obtained more favourable subjective ratings.

Conclusion: Juul's PK profile and user ratings suggest that it could be more effective than other EC products in helping smokers to quit smoking, but it may also have a higher potential to generate regular use in non-smokers.