Acute effects of electronic nicotine delivery system liquid nicotine form and sweet enhancer among people who use inhaled tobacco products.
Level 2 - randomized trial
Individual within-subject crossover clinical laboratory trial
PubMed 42060406 · doi:10.1037/pha0000847
What was done
Thirteen participants who use inhaled tobacco products completed four clinical laboratory sessions in a within-subject crossover design. Sessions evaluated combinations of e-liquid protonated nicotine ratios (0:100 vs. 40:60 freebase to protonated nicotine) and sweet enhancer content (unsweetened vs. sweetened with ethyl maltol). Each session comprised a 10-puff directed use period, a 30-minute ad libitum use period, and an own-brand challenge. Measured outcomes included plasma nicotine concentration, puff topography (volume and duration), liquid consumption, heart rate, and subjective sensory and drug effects.
What was found
The abstract reports directional differences without numerical values or effect sizes. Fully protonated e-liquid (0:100) led to a greater plasma nicotine boost, longer puff duration, and larger puff volume compared with the 40:60 formulation. Sweet enhancer did not alter nicotine delivery but increased flavor perception and appeal when paired with the 0:100 formulation. Unsweetened formulations were associated with greater nausea, whereas 40:60 liquids were rated as harsher and more irritating. The 0:100 liquids increased concentration ratings, while 40:60 liquids elicited a stronger immediate desire to use the product again.
Why it matters
This study demonstrates that e-liquid formulation characteristics beyond nicotine concentration—specifically nicotine protonation state and sweet enhancers—directly modify puffing behavior, systemic nicotine delivery, and product appeal. These factors represent concrete targets for tobacco regulatory standards aimed at reducing abuse liability.
Limits
The sample size is very small (n = 13). The abstract reports no numerical data, confidence intervals, or p-values. As an acute laboratory experiment, findings may not reflect long-term naturalistic use patterns, dependence risk, or cessation behavior. Only one sweet enhancer (ethyl maltol) and two specific protonation ratios were evaluated.
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.