Impact of e-liquid flavors on nicotine intake and pharmacology of e-cigarettes

Abstract

Objectives To describe the effect of e-liquid flavors on nicotine intake and pharmacology of e-cigarettes. Methods 11 males and 3 females participated in a 3-day inpatient crossover study with strawberry, tobacco, and their usual flavor e-liquid. Nicotine levels were nominally 18 mg/ml in the strawberry (pH 8.29) and tobacco (pH 9.10) e-liquids and ranged between 3–18 mg/ml in the usual brands (mean pH 6.80). Each day consisted of a 15-puff session followed by 4 hours of abstinence, then 90 minutes of ad libitum use. Subjects used a KangerTech mini ProTank 3. Results After 15 puffs, the amount of nicotine inhaled and systemically retained were not significantly different between the strawberry and tobacco e-liquids but plasma AUC(0→180) was significantly higher with the strawberry e-liquid. While not significantly different, Cmax was 22% higher and various early time point AUCs to measure rate of rise of nicotine in blood ranged between 17–23% higher with the strawberry e-liquid compared to the tobacco e-liquid. During ad libitum use, systemic exposure to nicotine (AUC(0→90)) was the same for the tobacco and usual brand e-liquids but were both significantly lower than after using the strawberry e-liquid. The usual flavors were more liked and satisfying than the strawberry and tobacco e-liquids. Conclusion Flavors influence nicotine exposure through flavor liking, may affect rate of nicotine absorption possibly through pH effects, and contribute to heart rate acceleration and subjective effects of e-cigarettes. E-cigarette users titrate their nicotine exposure but the extent of titration may vary across flavors.

Nicotine absorption from e-cigarettes over 12 months

“…We observed an increase in reports of the use of fruit flavoured e-liquids (35% to 51%) and a decrease in tobacco flavoured e-liquids (18% to 9%); a change which is consistent with national trends in e-cigarette flavours (ASH, 2017). Recent studies suggest that device type, PG/VG ratio , and flavours play a role in nicotine delivery (Farsalinos et al 2014;Kosmider at al 2018, St Helen et al 2017Spindle et al 2018) . Thus, changes to flavourings and device types including the subsequent increase in device power, may also contribute to more effective nicotine delivery helping to offset the effect of reducing nicotine concentration in the e-liquid.…”

Twenty‐four‐hour subjective and pharmacological effects of ad‐libitum electronic and combustible cigarette use among dual users

“…Nicotine exposure studies typically incorporate single‐use sessions with fixed puffing bouts or short‐term ad‐libitum procedures. Plasma nicotine concentrations are typically higher from ad‐libitum use compared to fixed puffing , perhaps because ad‐libitum procedures allow e‐cigarette users to self‐administer aerosols to achieve desired nicotine levels. However, ad‐libitum periods used in pharmacokinetic studies are typically brief (5–115 minutes) .…”

e‐Cigarettes for smoking cessation: Do they deliver?

“…In order to better understand the adverse events (AEs) associated with e‐cigarette use, it is useful to begin with the various chemicals found in these solutions as well as in the heated vapours which can be formed from chemical reactions resulting from the heating process . The solutions used to prepare the nicotine for vapourizing typically use a variety of solvents including propylene glycol, ethylene glycol, glycerol and polyethylene glycol with various concentrations of nicotine (see section ) and over 7000 flavouring agents that may add potentially toxic substances and possibly affect the pharmacokinetics of nicotine . Chemical analysis studies have identified many types of substances present in the vapours that can be categorized into four distinct chemical entities: carbonyl compounds, volatile organic compounds (VOCs), tobacco‐specific nitrosamines (TSNAs) and metals.…”