E-cigarettes an evidence update A report commissioned by Public Health England

E-cigarettes: an evidence updateOncken et al., (2015) also examined nicotine delivery in a tank system EC (Joye eGo-Cwith 18 mg/ml nicotine e-liquid) in 20 smokers who were asked to use an EC for twoweeks[123]. Participants were asked to use the EC for 5 minutes ad lib in two laboratorysessions where blood samples were taken for PK analysis. Blood nicotineconcentrations increased, significantly, by 4 ng/ml (Cmax 8.2 ng/ml) at the first sessionand 5.1 ng/ml (Cmax 9.3 ng/ml) at the second session. These levels were reached atfive minutes.Studies that examine cotinine as a measure of nicotine replacement in vapersWe found eight studies that reported on cotinine in urine, blood or saliva as a marker ofnicotine exposure in people using EC.In an RCT of nicotine containing EC versus placebo Caponnetto and colleagues (2013)measured salivary cotinine in participants who had stopped smoking cigarettes, butwere still vaping EC (Categoria 7.5mg/ml)[40]. After 12 weeks of use the mean salivarycotinine concentration was 67.8 ng/ml, which is at the lower end of what is typicallyobserved in smokers (eg 66.9-283.7 ng/ml).In a study that randomised 48 smokers unwilling to quit to one of two tank system EC(18mg/ml nicotine) or to continue to smoke found that at 8 month follow-up meansalivary cotinine did not significantly differ between those who had stopped smoking butwere vaping (428.27 ng/ml), achieved a ≥50% reduction in cigarette consumption(356.49 ng/ml) and those who continued to smoke (545.23 ng/ml, SD = 46.32)[41].Van Staden et al., (2013) examined the change in serum cotinine in 13 smokers whowere asked to stop smoking and instead use a Twisp eGo (18mg/ml nicotine) tanksystem EC for two weeks[113]. There was a significant decrease in cotinine frombaseline 287.25 ± 136.05 to two weeks 97.01 ± 80.91 ng/ml suggesting that the ECused did not provide as much nicotine as participants usual cigarettes.Norton et al., (2014) observed a similar result in 16 abstinent smokers who used acigalike EC (11 mg/ml) for five days, finding a significant decrease in saliva cotininebetween baseline (338.0 ng/ml) and day five (178.4 ng/ml)[112].Flouris et al., (2013) measured serum cotinine in 15 smokers, who had abstainedovernight, after smoking two of their usual cigarettes over 30 minutes and after 30minutes of vaping a cigalike EC (Giant, 11mg/ml)[130]. EC and cigarettes producedsimilar effects on serum cotinine levels (60.6 ± 34.3 versus 61.3 ± 36.6 ng/ml). Howevermeasurement of cotinine would not give an accurate indicator of exposure in an acutestudy such as this.110