Effects of Nicotine Concentration, PG/VG Ratio, and Nicotine Form on Sensory Perceptions and Subjective Effects Among Adults Who Vape

Significance: Sensory and subjective effects contribute to consumer response toward electronic nicotine delivery systems (ENDS). Evaluating the relative contributions of nicotine concentration, form (salt vs freebase), and carrier concentration (PG/VG ratio) is important to understanding why formulations may be more attractive. Methods: Participants were 78 adults (age ≥21) with no sensory deficits who used ENDS daily, randomized to one of two sub-studies. In Study A, 38 participants sampled tobacco-flavored e-liquids varying in PG/VG ratio (30/70, 60/40, 100/0) and nicotine concentration (0, 18, 36 mg/mL freebase). In Study B, 40 participants sampled e-liquids varying in nicotine form (salt, freebase) and concentration (0, 18, 36 mg/mL). Questionnaires assessed sensory and subjective effects. Generalized estimating equation (GEE) models examined the effects of experimental factors on these ratings. Results: Nicotine concentration was strongly related to a wide array of sensory and subjective effects measures, generally following a dose-response pattern. PG/VG showed relationships with a subset of hedonic effects independent of nicotine. There were no significant differences observed for sensory or subjective measures between salt versus freebase nicotine. Conclusions: Nicotine concentration showed consistent associations with sensory response to e-liquids when delivered in the same device. Sensory and behavioral responses to different e-liquid compositions may help contextualize ENDS usage patterns, risk perceptions, and behaviors.