Twenty‐four‐hour subjective and pharmacological effects of ad‐libitum electronic and combustible cigarette use among dual users

Background and Aims Relative pharmacological effects of e‐cigarettes and cigarettes during 24 hours of ad‐libitum use have not been described. In this study, 24‐hour blood plasma nicotine concentrations and 48‐hour subjective effects with use of cigarettes and e‐cigarettes were measured among dual users. Design Two‐arm within‐subject cross‐over design with preferred e‐cigarette or cigarette ad‐libitum use over 48 hours. Setting Hospital research ward in San Francisco, California, USA. Participants Thirty‐six healthy dual users of e‐cigarettes and cigarettes ( n = 8, 25% females). Measurements Twenty‐four‐hour blood plasma nicotine and cotinine concentrations and 48‐hour self‐reported nicotine withdrawal symptoms and rewarding effects. Findings Analyses used analysis of variance (ANOVA)‐based mixed models with order of product (e‐cigarette or cigarette) and product type (combustible cigarette or type of e‐cigarette) as fixed effects, and subject as a repeated effect. During a 24‐hour period, e‐cigarettes produced lower nicotine exposure than cigarettes for the majority of users, although 25% received more nicotine from e‐cigarettes, which was predicted by more frequent e‐cigarette use or greater dependence. Compared to cigarette smoking, nicotine exposure for variable‐power tank users was similar, while cig‐a‐like ( t (30) = 2.71, P = 0.011, d = 0.745) and fixed‐power tank users ( t (30) = 3.37, P = 0.002, d = 0.993) were exposed to less nicotine. Cigarettes were rated higher than e‐cigarettes on some desirable subjective effects (e.g. psychological reward, t (322) = 7.24 P < 0.001, d = 0.432), but withdrawal symptom reduction was comparable. No differences were found between e‐cigarette types, but Bayes factors indicate that these measures were insensitive. Conclusions During a 24‐hour period in a hospital setting in the United States, nicotine exposure for dual users of e‐cigarettes and cigarettes was similar when using cigarettes or variable‐power tank devices only but was lower for those using cig‐a‐like or fixed‐power devices only. Despite lower nicotine levels, all types of e‐cigarette were effective in preventing withdrawal symptoms. E‐cigarettes were rated less rewarding than cigarettes.