Effects of nicotine form and tobacco flavor on pharmacokinetics, subjective effects, and behavioral indicators of abuse liability of e-cigarettes.
Level 2 - randomized trial
Double-blind randomized within-subject crossover clinical trial
PubMed 41863629 · doi:10.1093/ntr/ntag058
What was done
In a double-blind, within-subject randomized clinical trial (NCT04231539), regular e-cigarette users completed a standardized puffing protocol across four liquid formulations of equivalent nicotine concentration (25.5 ± 2.4 mg/mL): unflavored free-base, tobacco-flavored free-base, unflavored salt-based, and tobacco-flavored salt-based nicotine. Outcomes evaluated using linear mixed-effects models and ANOVA included pharmacokinetic parameters (AUC, Cmax, Tmax), subjective drug effects (liking, withdrawal relief, sensory attributes), and behavioral economic demand.
What was found
Salt-based nicotine formulations generated significantly higher maximum concentration (Cmax) values (P = .028), were rated as significantly less harsh (P < .001), and produced a more intense cooling sensation (P = .002) than free-base formulations. Tobacco flavoring increased cooling sensation intensity (P = .013) and showed a non-significant trend toward a greater feeling of nicotine effect (P = .055) compared to unflavored liquid. Formulations with salt-based nicotine consistently outperformed free-base nicotine across nominal rankings regardless of flavor. Specific numerical point estimates for PK and demand endpoints were not reported in the abstract.
Why it matters
These findings demonstrate that nicotine salt formulation plays a greater role than tobacco flavoring in enhancing systemic nicotine delivery and reducing sensory aversiveness, highlighting a primary mechanism behind the high abuse liability of modern e-cigarettes.
Limits
The abstract does not disclose the sample size, participant demographics, or quantitative values for pharmacokinetics and behavioral economic demand. The standardized puffing protocol may not reflect naturalistic ad libitum use, and results in regular users using tobacco flavor may not generalize to non-tobacco flavors, youth, or smokers attempting cessation.
Cited by
- supports E-cigarette manufacturers alter the pH of nicotine solutions to reduce throat irritation and bypass the respiratory tract's natural aversion reflex.