Abstract

© 2015 Society for the Study of Addiction. Aims: To measure the systemic retention of nicotine, propylene glycol and vegetable glycerin in electronic cigarette users, and assess the abuse liability of e-cigarettes by characterizing nicotine pharmacokinetics. Design: E-cigarette users recruited over the internet participated in a 1-day research ward study. Subjects took 15 puffs from their usual brand of e-cigarette. Exhaled breath was trapped in gas-washing bottles and blood was sampled before and several times after use. Setting: San Francisco, California, USA. Participants: Thirteen healthy, experienced adult e-cigarette users. Measurements: Plasma nicotine was analyzed by gas chromatography-mass spectrometry and nicotine, VG and PG in e-liquids and gas traps were analyzed by LC-MS/MS. Heart rate changes and subjective effects were assessed. Findings: E-cigarettes delivered an average of 1.33 mg [mean and 95% confidence interval ] of nicotine, and 93.8% of the inhaled dose, 1.22 was systemically retained. Average maximum plasma nicotine concentration was 8.4 ng/ml and time of maximal concentration was 2-5 minutes. One participant had Tmax of 30minutes. 84.4% and 91.7% of VG and PG, respectively, was systemically retained. Heart rate increased by an average of 8.0 beats per minute after 5minutes. Withdrawal and urge to smoke decreased and the e-cigarettes were described as satisfying. Conclusions: E-cigarettes can deliver levels of nicotine that are comparable to or higher than typical tobacco cigarettes, with similar systemic retention. Although the average maximum plasma nicotine concentration in experienced e-cigarette users appears to be generally lower than what has been reported from tobacco cigarette use, the shape of the pharmacokinetic curve is similar, suggesting addictive potential.