Monitoring nicotine intake in human volunteers transitioning from cigarette smoking to e-cigarette use

Introduction Use of electronic cigarettes (ECs) has increased rapidly since they were introduced in Europe in 2006 especially in the UK. Claims have been made for a role in tobacco harm reduction and smoking cessation. Key to these claims is the ability of EC to maintain nicotine levels to limit cravings, withdrawal and nicotine dependence. Therefore, the aim of the current study is to monitor nicotine intake in heavy smokers (>10 cig/day, n=13 completed) transitioning from cigarette smoking to EC-only use whilst collecting psychometric data on nicotine dependence (Fagerstrom), withdrawal (Minnesota), anxiety, depression and sleep quality. Material and Methods Urine and saliva samples as well as psychometric questionnaire data were collected at baseline (visits 1 and 2) and at days 3, 7, 21 and 28 following start of EC use. An UHPLC-HESI-HRMS method was developed, validated and applied to the determination of nicotine and its main metabolite cotinine in urine and saliva. Results The baseline median (interquartile range) urinary nicotine and cotinine levels were determined as 1534 ng/mg creatinine (317-2478) and 2082 ng/mg creatinine (1727-3632), whereas salivary nicotine and cotinine levels were 145 ng/ml (26-265) and 329 ng/ml (198-440), respectively. One-way repeated measures Anova demonstrated a significant decrease in urinary nicotine and cotinine concentration from baseline at 3 post-transition visits. A significant reduction was also observed in salivary nicotine levels on days 3 and 21 after EC transition and in salivary cotinine levels at each post-transition visit compared to baseline. Both urge and strength of urges to smoke were significantly decreased by 28days compared to baseline. Conclusions These findings offer support that EC can be effective in reducing nicotine consumption and cravings for cigarettes, suggesting the potential use of EC as a smoking cessation tool. However, the inability to achieve levels of nicotine comparable to smokers may contribute to relapse. Funding Statement Funded by European Commission Horizon 2020 programme.