BACKGROUND AND AIMS Relative pharmacological effects of e-cigarettes and cigarettes over 24 h of ad libitum use have not been described. In this study 24 h blood plasma nicotine concentrations and 48 h subjective effects with use of cigarettes and e-cigarettes were measured among dual users. DESIGN Two-arm within-subject crossover design with preferred e-cigarette or cigarette ad libitum use over 48 h. SETTING Hospital research ward in San Francisco, California, USA. PARTICIPANTS 36 healthy dual users of e-cigarettes and cigarettes (N=8, 25% females). MEASUREMENTS 24 h blood plasma nicotine and cotinine concentrations and 48 h self-reported nicotine withdrawal symptoms and rewarding effects. FINDINGS Analyses used 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. Over a 24 h period, e-cigarettes produced lower nicotine exposure than cigarettes for the majority of users, though 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=.011, d=.745) and fixed-power tank users (t[30]=3.37, p=.002, d=.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<.001, d=.432)), but withdrawal symptom reduction was comparable. No differences were found between e-cigarette types but Bayes factors indicate these measures were insensitive. CONCLUSIONS Across a 24h-period in a hospital setting in the US, 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.

中文翻译：

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双人用户随意使用电子烟和可燃卷烟的 24 小时主观和药理影响

背景和目的 电子烟和香烟在随意使用 24 小时内的相对药理作用尚未被描述。在这项研究中，测量了双重使用者的 24 小时血浆尼古丁浓度和 48 小时使用香烟和电子烟的主观影响。设计 双臂受试者内交叉设计，首选电子烟或香烟随意使用超过 48 小时。在美国加利福尼亚州旧金山设置医院研究病房。参与者 36 名健康的电子烟和香烟双重使用者（N=8，25% 女性）。测量 24 小时血浆尼古丁和可替宁浓度以及 48 小时自我报告的尼古丁戒断症状和奖励效果。发现 分析使用基于方差分析的混合模型，产品顺序（电子烟或香烟）和产品类型（可燃香烟或电子烟类型）作为固定效应，主题作为重复效应。在 24 小时内，对于大多数用户来说，电子烟产生的尼古丁暴露量低于香烟，尽管 25% 的人从电子烟中获得了更多的尼古丁——这是由更频繁地使用电子烟或更大程度的依赖所预测的。与吸烟相比，可变功率油箱使用者的尼古丁暴露量相似，而类香烟 (t[30]=2.71, p=.011, d=.745) 和固定功率油箱使用者 (t[30] ]=3.37, p=.002, d=.993) 暴露于较少的尼古丁。在一些理想的主观效果（例如心理奖励，t[322]=7.24 p<.001, d=.432)）上，香烟的评分高于电子烟，但戒断症状的减少是可比的。电子烟类型之间没有发现差异，但贝叶斯因素表明这些措施不敏感。结论 在美国的医院环境中，在 24 小时内，电子烟和香烟双重使用者的尼古丁暴露在仅使用香烟或可变功率罐装置时相似，但使用类香烟或固定香烟的人的尼古丁暴露量较低仅限电源设备。尽管尼古丁含量较低，但所有类型的电子烟都能有效预防戒断症状。电子烟的奖励不如香烟。电子烟和香烟双重使用者的尼古丁暴露在仅使用香烟或可变功率油箱设备时相似，但仅使用类香烟或固定功率设备的人的尼古丁暴露量较低。尽管尼古丁含量较低，但所有类型的电子烟都能有效预防戒断症状。电子烟的奖励不如香烟。电子烟和香烟双重使用者的尼古丁暴露在仅使用香烟或可变功率油箱设备时相似，但仅使用类香烟或固定功率设备的人的尼古丁暴露量较低。尽管尼古丁含量较低，但所有类型的电子烟都能有效预防戒断症状。电子烟的奖励不如香烟。