People using electronic nicotine delivery systems (ENDS) with cigarette-like nicotine delivery may reduce their exposure to a tobacco-specific carcinogen metabolite, even with concurrent smoking, according to study results published in The Lancet Respiratory Medicine.

Investigators conducted a 4-arm, parallel-group, randomized controlled study ( Identifier: NCT02342795) to determine how much ENDS or nonnicotine cigarette substitutes influence toxicant exposure related to tobacco and cigarette consumption in individuals who were interested in reducing their smoking frequency.

Adults aged 21 to 65 years who smoked more than 9 cigarettes a day for at least the past year, who wanted to reduce their smoking frequency, but not quit, were invited to be randomly assigned to receive either a cartomizer-based, pen-style ENDS with 0 mg/mL, 8 mg/mL, or 36 mg/mL liquid nicotine or a nonelectronic cigarette-shaped plastic tube that contained no nicotine or aerosol (cigarette substitute; unmasked) for 24 weeks.

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The primary outcome measured the concentration of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a tobacco-specific carcinogen metabolite. NNAL concentrations were measured via urine samples, which were taken at randomization, and at weeks 4, 12, and 24 of the study.

A total of 520 participants were randomly assigned to 1 of 4 groups (n=130 per group); however, 36% of patients (n=188) were lost to follow-up by the end of the study. Compared with participants who stayed in the study, these participants were more likely to be younger (mean age, 43.6 years; P =.0001), have a lower level of education (P =.030), and have smoked for fewer years (mean 14.5 years; P =.0032).

At 24 weeks, the urinary total NNAL in the cohort using 36 mg/mL liquid nicotine vs the cigarette substitute cohort was 210.80 pg/mg vs 346.09 pg/mg creatinine (P =.0061). Significant differences in NNAL levels were not observed for any other groups. Serious adverse events were also similar among all groups, and all events were unrelated or unlikely to be related to the study product use.

The investigators noted that participant attrition was a limitation of the study and multiple imputations and sensitivity analyses were performed to remove bias. The decline in the use of the study product throughout the analysis was another limitation.

“In this trial, where smoking reduction was encouraged over 24 weeks with multiple visits and assessments, we found that an ENDS was most likely to help smokers reduce toxicant exposure and cigarette consumption when it was capable of delivering nicotine at levels similar to that of a cigarette,” the authors wrote.

Disclosure: Some study authors declared affiliations with the pharmaceutical, biotech, and/or device companies. Please see the original article for a full list of authors’ disclosures.


Cobb CO, Foulds J, Yen M-S, et al; for the Randomised Control Trial Methods Workgroup of the Center for the Study of Tobacco Products. Effects of an electronic nicotine delivery system with 0, 8, or 36 mg/mL liquid nicotine versus a cigarette substitute on tobacco-related toxicant exposure: a four-arm, parallel-group, randomised, controlled trial. Lancet Respir Med. Published online April 12, 2021. doi:10.1016/s2213-2600(21)00022-9

This article originally appeared on Pulmonology Advisor