Comparison of Measurement Methods for Electronic Cigarette Puff Topography

Abuse Liability of Electronic Cigarettes in Never-Smoking Electronic Cigarette Users

INTRODUCTION

Modern pod-style electronic cigarette (ECIG) devices appear to have a high potential for abuse, though minimal laboratory-based work has evaluated the effects of these products among users of ECIGs without a history of cigarette smoking. Thus, this study compared the subjective and behavioral effects of pod-style ECIGs to nicotine gum in such a sample.

AIMS AND METHODS

Young adult (Mage = 20.75 years, SD = 2.02) users of pod-style ECIGs (N = 16) completed three conditions that differed by product used: own ECIG, 4 mg nicotine gum, or placebo gum. Within sessions, participants abstained from nicotine/tobacco use overnight and then experienced two product use bouts separated by 60 minutes. Specifically, they either used their own ECIG ad libitum for 5 minutes or chewed the gum for 30 minutes. Before and/or after each bout, they completed subjective (eg, craving, product effects) and behavioral (multiple choice procedure) measures.

RESULTS

Significant decreases in intention to vape were observed from before to after use of ECIGs (p < .01) but not after 4 mg or placebo gum. Similarly, ratings of relief and satisfaction were significantly higher for ECIGs than for either gum dose at both bouts (p's < .01). The crossover point was higher for ECIGs than for gum, though differences were not significant.

CONCLUSIONS

Pod-style devices were more reinforcing than nicotine gum in a vulnerable population of users of ECIGs. There is a clear need for continued monitoring of these modern devices, which are known for containing high concentrations of nicotine and for being attractive to younger populations.

IMPLICATIONS

People with ECIG experience, but who have never regularly smoked cigarettes, represent a growing population of nicotine users. Results demonstrate that modern ECIG devices are more reinforcing than nicotine gum and therefore have a higher abuse liability for this vulnerable population.

Addiction potential of combustible menthol cigarette alternatives: a randomised cross-over trial

INTRODUCTION

The Food and Drug Administration (FDA) has issued proposed product standards banning menthol as a characterising flavour in cigarettes and cigars. The public health benefits of these product standards may be attenuated by the role of plausible substitutes in the marketplace. Therefore, the present study examined the addiction potential of plausible combustible menthol alternatives compared with usual brand menthol cigarettes (UBMC).

METHODS

Ninety-eight adult menthol cigarette smokers completed four visits, smoking their UBMC at the first session and three menthol cigarette alternatives in random order at the subsequent visits: (1) a preassembled menthol roll-your-own (mRYO) cigarette using menthol pipe tobacco and mentholated cigarette tube, (2) a menthol filtered little cigar (mFLC) and (3) a non-menthol cigarette (NMC). Measures of smoking topography, exhaled carbon monoxide (CO), craving and withdrawal, subjective effects and behavioural economic demand indices were assessed.

RESULTS

Compared with UBMC, menthol cigarette alternatives resulted in different puffing topography and CO exposure (except mRYO), and lower levels of positive subjective experience and behavioural economic demand indices. Among the alternative products, participants reported the highest level of positive subjective experience and higher demand for mRYO, compared with mFLC and NMC. Similarly, participants were significantly more likely to want to try again, purchase and use the mRYO product regularly compared with mFLC and NMC.

CONCLUSIONS AND RELEVANCE

mRYO cigarettes were the most highly rated cigarette alternative among study products, suggesting their potential appeal as a menthol cigarette substitute and needed inclusion of menthol pipe tobacco and cigarette tubes in FDA's proposed ban.

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.

E-cigarette puffing topography: The importance of assessing user behaviour to inform emissions testing

Analysis of the chemical composition of e-cigarette emissions is an important step in determining whether e-cigarettes offer both individual and population-level harm reduction potential. Commonly, e-cigarette emissions for chemical analysis are collected when using e-cigarettes according to standardised puffing regimens, such as those recommended by the International Organization for Standardization (ISO) or the Cooperation Centre for Scientific Research Relative to Tobacco (CORESTA). While the use of such standard puffing regimens affords a degree of uniformity between studies and are also recommended by regulatory authorities who require the submission of e-cigarette emissions data to make decisions regarding allowing a product to be commercially marketed, the standardised regimens do not necessarily reflect human puffing behaviour. This can lead to under- or over-estimating real-world emissions from e-cigarettes and inaccuracy in determining their harm reduction potential. In this review, we describe how human puffing behaviour (topography) information can be collected both in the clinical laboratory and in the real world using a variety of different methodologies. We further discuss how this information can be used to dictate e-cigarette puffing regimens for collecting emissions for chemical analyses and how this may lead to better predictions both of human yields of e-cigarette emissions constituents and of risk assessments to predict e-cigarette tobacco harm reduction potential.

Comparing POD and MOD ENDS Users' Product Characteristics, Use Behaviors, and Nicotine Exposure

INTRODUCTION

POD electronic nicotine delivery systems (ENDS), often containing high concentrations of nicotine salts, have replaced MODs (ie, open/modifiable devices) as the most popular devices. The purpose of this study was to compare device/liquid characteristics, use behavior, and nicotine exposure between POD and MOD users.

METHODS

Data from the initial visit of a prospective observational study of exclusive ENDS users compared MOD (n = 48) and POD (n = 37) users. Participants completed questionnaires on demographic characteristics, patterns of ENDS use, and ENDS features. A urine sample was collected to test for cotinine and an ENDS liquid sample was collected to test for nicotine and salts. Puff topography was captured during an ad libitum bout at the end of the session.

RESULTS

MOD and POD users did not differ on demographic characteristics. MOD users reported purchasing more liquid in the past month than POD users (180.4 ± 28.0 vs. 50.9 ± 9.0 ml, p < .001). Differences in characteristics of devices used by MOD and POD users included flavor type (p = .029), nicotine concentration (liquids used by MOD users contained less nicotine than those used by POD users: 8.9 ± 2.0 vs. 41.6 ± 3.2 mg/ml, p < .001), and presence of the nicotine salt (fewer MOD liquids had salts present than POD liquids: 11.9% vs. 77.4%, p < .001). User groups did not differ on urinary cotinine levels or puff topography (ps > .05).

CONCLUSIONS

Despite different characteristics of MOD and POD ENDS, users of those products are exposed to similar amounts of nicotine, likely due to using more liquid among MOD users.

IMPLICATIONS

This study directly compares ENDS product characteristics, user behavior, and nicotine exposure between MOD and POD ENDS users. Although POD products contained higher nicotine concentrations compared to MOD products, users of PODs reported consuming less liquid than MOD users. Ultimately, MOD and POD users were exposed to similar levels of nicotine, suggesting users behaviorally compensate for differences in product characteristics.

Preliminary evaluation of short-term abstinence effects among never-smoking experienced users of modern electronic cigarettes

INTRODUCTION

ECIG use has increased among non-smokers, with the potential negative consequence of developing nicotine dependence. ECIG users report withdrawal symptoms upon abstinence, though the significance of these symptoms has been questioned. This preliminary study aimed to characterize the early timecourse of ECIG withdrawal under forced abstinence.

METHODS

Fifteen never-smoking ECIG users completed two conditions whereby participants either abstained from ECIG use (abstinence) or used their own ECIG (ad lib) for 3 hours. Puff topography in this latter condition was measured via video observation. Outcome measures included heart rate, subjective ratings of withdrawal, cognitive performance, and choice behavior.

RESULTS

Heart rate was lower during abstinence compared to ad lib use (F=12.60, p<.01, ƞp  2=0.47). Higher levels of craving (F=4.98, p<.05, ƞp  2=0.26) and lower levels of nicotine effects (e.g., dizzy, F=4.62, p<.05, ƞp  2=0.36) were reported during abstinence compared to ad lib use. Interaction effects were observed for both factors of the Questionnaire of Smoking Urges: Brief (Fs>3.56, ps<.05, ƞp  2s=0.21-0.27), with factor scores increasing from baseline to 90 minutes in the abstinent condition only. Inhibitory control was impaired at 120 min in the abstinent condition only (F=7.51, p<.05, ƞp  2=0.50).

CONCLUSIONS

Never-smoking ECIG users experienced aversive withdrawal symptoms within 2-3 hours of abstinence. Future work should include other control conditions, such as placebo ECIGs or nicotine replacement therapy, and biomarkers of nicotine exposure, as well as examine withdrawal as a function of device type.

IMPLICATIONS

Never-smoking ECIG users experience some aversive nicotine withdrawal symptoms within two to three hours of abstinence. Relative to ad lib ECIG use, abstinence decreased heart rate and inhibitory control, as well as increased subjective ratings of withdrawal such as craving and intention to vape. Those same symptoms might be suppressed by self-administration of ECIGs. Experiencing withdrawal upon abstinence may indicate that ECIGs can cause dependence without a history of other tobacco use.