Influence of nicotine form and nicotine flux on puffing behavior and mouth-level exposure to nicotine from electronic nicotine delivery systems.

BACKGROUND: Nicotine form (freebase/protonated) and nicotine flux (rate at which nicotine is emitted) are two factors that can affect the dose of nicotine inhaled by individuals using electronic nicotine delivery systems (ENDS) because they can influence puffing behavior. The nicotine dose for each puff also is directly proportional to nicotine flux (i.e., dose/puff=nicotine flux*puff duration). This study examines the effect of nicotine form and flux on puffing parameters and mouth-level nicotine exposure. METHODS: Thirty-two dual ENDS and combustible cigarette participants completed five visits that differed by nicotine form (freebase or protonated) and nicotine flux (14 or 35µg/sec); a zero-nicotine condition was a negative control. Participants used a Subox Mini C ENDS, powered at 20W, during a 10-puff directed bout (B1) followed by a one-hour ad libitum bout (B2). Puffing parameters and mouth-level nicotine exposure were assessed using the American University of Beirut REALTIME instrument. RESULTS: Relative to protonated nicotine, freebase nicotine was associated with lower total puff duration (puff duration*number of puffs), lower flow rate in B1, lower liquid consumption, and lower mouth-level nicotine exposure. Increasing nicotine flux from 14 to 35µg/sec was associated with lower total puff duration in both bouts, as well as lower liquid consumption. Increasing nicotine flux was associated with higher mouth-level nicotine exposure in B1 only. CONCLUSION: ENDS with protonated nicotine may enhance nicotine exposure by promoting longer puffing and thus greater dose delivered. This work highlights the importance of accounting for interactions between nicotine form and flux when considering nicotine regulation for ENDS.

Physical activity matters for everyone's health, but individuals with multimorbidity benefit more.

Multimorbidity, defined as the presence of two or more chronic conditions, is increasingly prevalent and is a major contributor to ill health in old age. Physical activity (PA) is a key protective factor for health and individuals with multimorbidity could particularly benefit from engaging in PA. However, direct evidence that PA has greater health benefits in people with multimorbidity is lacking. The objective of the present study was to investigate whether the associations between PA and health were more pronounced in individuals with (vs. without) multimorbidity. We used data from 121,875 adults aged 50 to 96 years (mean age = 67 ± 10 years, 55% women) enrolled in the Survey of Health, Ageing and Retirement in Europe (SHARE). Multimorbidity and PA were self-reported. Health indicators were assessed using tests and validated scales. Variables were measured up to seven times over a 15-year period. Confounder-adjusted linear mixed-effects models were used to investigate the moderating role of multimorbidity on the associations of PA with the levels and trajectories of health indicators across aging. Results showed that multimorbidity was associated with declines in physical, cognitive, and mental health, as well as poorer general health. Conversely, PA was positively associated with these health indicators. We found a significant interaction between multimorbidity and PA, revealing that positive associations between PA and health indicators were strengthened in people with multimorbidity - although this stronger association became less pronounced in advanced age. These findings suggest that the protective role of PA for multiple health indicators is enhanced in individuals with multimorbidity.