Clinical Laboratory Evaluation of Electronic Cigarettes/Electronic Nicotine Delivery Systems: Methodological Challenges

Partial Nicotine Reduction and E-Cigarette Users' Puffing Behaviors Among Adults Aged 21 to 35 Years: A Randomized Crossover Clinical Trial

Importance

The advent of salt-based, high-nicotine electronic nicotine delivery systems [e-cigarettes] has contributed to their epidemic use among young people in the US, necessitating the need for policies to address the addictiveness of these products.

Objective

To evaluate the effect of partial nicotine reduction on new-generation e-cigarette users' puffing behaviors.

Design, Setting, and Participants

This randomized crossover clinical trial was conducted at the Clinical Research Lab for Tobacco Smoking at Florida International University in Miami between April 15, 2022, and October 17, 2023. Using a volunteering sampling method by distributing flyers and advertisements, current e-cigarette users (who preferred 5% nicotine concentration), aged 21 to 35 years, were included.

Intervention

In a crossover design, participants completed 2 sessions of the same product (JUUL or NJOY) that differed by nicotine concentration (3% [JUUL] or 2.4% [NJOY] and 5% [JUUL or NJOY]) in random order. In each session, participants vaped up to 60 minutes ad libitum, preceded by 12 hours of nicotine abstinence.

Main Outcomes and Measures

The primary outcomes were puffing topography parameters (eg, total session time, puffing time, total puffing number, interpuff interval, total inhaled volume, average puff volume, duration, and flow rate) measured during each session and plasma nicotine measured before and after each session.

Results

Among 735 participants who were approached for eligibility, 675 were excluded, and 10 did not complete session 2. Of the 50 remaining current e-cigarette users (mean [SD] age, 23 [3] years; 56% men), 23 (46%) were low nicotine dependent. The median topography parameters were significantly higher during the e-cigarette use sessions with 3% or 2.4% nicotine concentration compared with 5% nicotine concentration for 3 outcomes: puffing time (1.3 minutes [IQR, 0.3-9.4 minutes] vs 1.2 minutes [IQR, 0.2-5.6 minutes]; P = .02), puff duration (2.6 seconds [IQR, 0.8-6.9 seconds] vs 2.4 seconds [IQR, 0.4-6.6 seconds]; P = .02), and total inhaled volume (1990.0 mL [IQR, 279.0-24 400.0 mL] vs 1490.0 mL [IQR, 148.0-14 300.0 mL]; P = .05). The median plasma nicotine boost observed in the 5% nicotine concentration condition (0.0060 mg/L [IQR, 0.0001-0.0249 mg/L]) was significantly higher than that in the 3% or 2.4% session (0.0043 mg/L [IQR, 0.0008-0.0225 mg/L]) (P = .001). Additionally, deeper puffing (increased average puff duration and average puff volume) was observed in participants with higher nicotine dependence (1.42 seconds [95% CI, 1.12-1.80 seconds]; P = .03) and male users (1.38 mL [95% CI, 1.09-1.75 mL]; P = .04) in response to nicotine reduction.

Conclusions and Relevance

This randomized crossover clinical trial provides direct evidence that partial nicotine reduction in salt-based e-cigarettes was associated with acute compensatory puffing and the potential for increased exposure to toxicants. However, given the reduced nicotine delivery associated with nicotine reduction, the acute compensatory response observed in this study may not preclude a population benefit due to the marketing of less addictive products. These results suggest that at least for current e-cigarette users, partial nicotine reduction can lead to enhanced exposure to some toxicants in the short term.

Trial Registration

ClinicalTrials.gov Identifier: NCT05205382.

Electronic cigarette use intensity measurement challenges and regulatory implications

Assessing tobacco use intensity allows researchers to examine tobacco use in greater detail than assessing ever or current use only. Tobacco use intensity measures have been developed that are specific to tobacco products, such as asking smokers to report number of cigarettes smoked per day. However, consensus on electronic cigarette use intensity measures that can be used for survey research has yet to be established due to electronic cigarette product and user behavior heterogeneity. While some survey measures that attempt to assess electronic cigarette use intensity exist, such as examining number of 'times' using an electronic cigarette per day, number of puffs taken from an electronic cigarette per day, volume of electronic cigarette liquid consumed per day, or nicotine concentration of electronic cigarette liquid, most measures have limitations. Challenges in electronic cigarette measurement often stem from variations across electronic cigarette device and liquid characteristics as well as the difficulty that many electronic cigarette users have regarding answering questions about their electronic cigarette device, liquid, or behavior. The inability for researchers to measure electronic cigarette use intensity accurately has important implications such as failing to detect unintended consequences of regulatory policies. Development of electronic cigarette use intensity measures, though not without its challenges, can improve understanding of electronic cigarette use behaviors and associated health outcomes and inform development of regulatory policies.

The Effect of Graphic Health Warning Labels Placed on the ENDS Device on Young Adult Users' Experience, Exposure and Intention to Use: A Pilot Study

This proof-of-concept study aims to evaluate the effect of placing graphic health warning labels (GHWLs) on the ENDS device on users' experience, puffing patterns, harm perception, nicotine exposure, and intention to quit or use in the future. JUUL users (n = 26, age 18-24 years; 69% male; 85% Hispanic) were recruited to complete two 60 minutes ad libitum sessions that differed by GHWL on the device (GHWL vs. no-GHWL control) in an experimental clinical lab study. Compared to the control session, using JUUL with GHWL on the device was significantly associated with reduced positive experiences such as pleasure, product liking, and user satisfaction (p-value < 0.05 for all). Also, after exposure to GHWL, participants were less interested in using the same product again (p-value = 0.007), even if it was the only product available on the market compared to control (p-value = 0.03). Trends toward reduced puffing behavior and nicotine boost were also noted during the GHWL, compared to control sessions. This pilot study shows that placing GHWL on the ENDS device may be an effective and promising strategy to reduce ENDS use among young people.

Device features and user behaviors as predictors of dependence among never-smoking electronic cigarette users: PATH Wave 4

INTRODUCTION

Electronic cigarettes (ECIGs) vary greatly in their ability to deliver nicotine, which suggests they may also vary in their ability to produce dependence. This study examined individual and combined ECIG device features, and also user behaviors, as predictors of dependence in never-smoking ECIG users. Methods Data were collected from 711 current ECIG users who had smoked <100 cigarettes in their lifetime at Wave 4 of the Population Assessment of Tobacco and Health (PATH) Study. Multivariable linear regressions examined individual (e.g., contains nicotine, uses a tank, flavor preference) and combined (e.g., refillable tanks, refillable mods) device features, and user behaviors (e.g., uses/day) as predictors of dependence, withdrawal, and craving after accounting for demographic variables. Results Results for ECIG dependence and craving showed a similar pattern; higher levels were observed for older age, more frequent past 30-day use, using an ECIG containing nicotine (vs no nicotine), and using a non-refillable cartridge or refillable tank style (vs disposables). Higher withdrawal levels were observed for higher education levels and individual device features of tank (vs no tank), cartridge (vs no cartridge), refillable (vs non-refillable), and "other" flavor preference (vs tobacco flavor). Lower withdrawal levels were associated with a preference for sweet/fruit flavor(s) (vs tobacco flavor). Conclusions Few use behaviors and device features, whether examined alone or in combination, predicted dependence-related outcomes. Findings underscore the challenge with regulating ECIG products in the current marketplace, which is inundated with a myriad of device types.

Association of frequency of perceived exposure to discrimination with tobacco withdrawal symptoms and smoking lapse behavior in African Americans

BACKGROUND AND AIMS

Frequent experiences of discrimination could increase vulnerability to tobacco withdrawal and smoking lapse in populations subject to tobacco-related health disparities. This laboratory study (2013-17) examined whether individual differences in perceived exposure to discrimination in one's daily life predicted tobacco withdrawal symptoms and smoking lapse behavior following acute tobacco deprivation in African American smokers.

DESIGN

Mixed design with the between-subjects continuous variable of perceived discrimination crossed with the within-subject variable of tobacco deprivation status (deprived versus non-deprived).

SETTING

Academic medical center in Los Angeles, CA, USA.

PARTICIPANTS

African American non-treatment seeking daily cigarette smokers (n = 607, ≥ 10 cig/day).

MEASUREMENTS

At a baseline visit, self-reported frequency of perceived exposure to discrimination in one's daily life was measured [everyday discrimination scale (EDDS)]. At two subsequent counterbalanced experimental visits (16-hour tobacco deprivation versus ad-libitum smoking), self-report assessments of various tobacco withdrawal symptom domains [Brief Questionnaire of Smoking Urges), Wisconsin Smoking Withdrawal Scale (WSWS), Profile of Mood States (POMS), Snaith-Hamilton Pleasure Scale (SHAPS) and Current Impulsivity Scale (CIS)) and a behavioral smoking lapse analogue task were measured.

FINDINGS

Adjusted models demonstrated that greater frequency of perceived exposure to discrimination was associated with larger deprivation-induced increases in acute urges to smoke to alleviate negative mood, several negative mood states and subjective cognitive functioning-effect sizes were small in magnitude (βs = 0.09-0.13; Ps < 0.02). Data were inconclusive for associations between perceived exposure to discrimination and deprivation-induced changes in cravings, urges to smoke for pleasure, positive mood reduction, other symptoms or smoking reinstatement behavior.

CONCLUSIONS

Frequency of perceived exposure to discrimination appears to be modestly associated with increased severity of some deprivation-induced tobacco withdrawal symptoms in African American smokers.

Vapers exhibit similar subjective nicotine dependence but lower nicotine reinforcing value compared to smokers

INTRODUCTION

E-cigarette use has increased rapidly over the last 10 years, mostly among smokers and ex-smokers. Although there may be some degree of dependency on nicotine via e-cigarette use, the nature of this dependency is poorly understood. The aim of this paper is to use tasks from behavioural economics to compare the value that smokers place on tobacco cigarettes to the value that vapers place on e-cigarettes.

METHOD

Exclusive current smokers (n = 25) and vapers (n = 20) attended one session where they completed the Cigarette/e-cigarette Dependence Scale, the Cigarette/e-cigarette Purchasing Task (CPT) and the Concurrent Choice Task (CCT). The CPT requires participants to indicate how many puffs of their chosen product they would purchase at increasing price points. The CCT requires participants to choose between earning a money point or a point towards a cigarette/e-cigarette after being presented with a neutral, money or cigarette/e-cigarette cue.

RESULTS

Overall scores on the self-report scales suggest a comparable level of dependency between smokers and vapers. The CPT revealed that vapers are more sensitive than smokers to escalating costs as consumption declined as costs increased. On the CCT, when primed with money, vapers showed a decrease in choosing e-cigarettes.

CONCLUSION

These findings suggest that, on behavioural economic tasks, tobacco cigarettes have a higher relative value than e-cigarettes. Vapers appear to place a lower limit on what they will spend to access e-cigarettes and more readily choose money over e-cigarette puffs when primed by money cues.

Electronic Cigarettes: Exposure to Secondhand Vapors at a Long-Term Healthcare Company

INTRODUCTION

Healthcare workers in long term care settings have limited control over their occupational secondhand exposure to electronic cigarettes and other tobacco products.

METHODS

The study aimed to identify the perceived frequency of exposure to exhaled electronic cigarette vapor on healthcare workers within two sites of a long-term healthcare company. An online survey was completed by 149 (out of approximately 500) employees that asked about electronic cigarette personal usage, concerns for exposure, exposure times, and demographic data.

RESULTS

Twelve percent of all survey respondents expressed concerns related to second-hand exposure. Of those exposed, employee estimated exposure time was 2.1 minutes per shift for electronic cigarettes compared to 12.1 minutes per shift for cigarettes/cigars/pipes.

CONCLUSIONS

Overall self-reported secondhand exposure to electronic cigarettes and cigarettes/cigars/pipes was low. To determine a definitive exposure level, quantitative sampling can be done related to chemical exposure via passive inhalation of the smoke and vapor cloud for cigarettes and electronic cigarettes, respectively. Education can be provided to healthcare workers and residents in long-term care facilities regarding risk of exposure to secondhand smoke to alleviate employees concerns with exposure.

Abuse liability of electronic cigarettes in men who are experienced electronic cigarette users

Most electronic cigarettes (e-cigs) aerosolize a nicotine-containing liquid that users inhale. Few experimental studies have examined e-cig abuse liability (the extent to which use of these products may lead to persistent and/or problematic use). In this study, 24 experienced male e-cig users completed 4 sessions that differed byproduct used: own e-cig (OWN), an eGo e-cig filled with participants' own brand/flavor liquid in 0 mg/mL nicotine (e-cig0), an eGo e-cig filled with the highest nicotine concentration available in participants' own brand/flavor (e-cighighest), and a U.S. Food and Drug Administration-approved nicotine inhaler (IN). Outcome measures included crossover point on the multiple-choice procedure, plasma nicotine delivery, and subjective effect profile. After 10 puffs, a significantly higher mean crossover point was observed for OWN at $1.35 (SD = 0.90) compared to e-cighighest at $0.88 (SD = 0.89), e-cig0 at $0.83 (SD = 0.79), and IN at $0.72 (SD = 0.84). Significant increases in mean plasma nicotine concentration were observed for OWN at 7.94 ng/mL (SD = 6.19) and e-cighighest at 7.51 ng/mL (SD = 5.39). Significant reductions in abstinence symptom suppression and higher ratings of satisfaction were observed for OWN and e-cighighest, with significantly less suppression and lower ratings of satisfaction for e-cig0 and IN. These findings suggest that human laboratory methods can be used to assess e-cig abuse liability and that nicotine-containing e-cigs have greater abuse liability than nicotine-free e-cigs and the IN. Potential regulations intended to limit e-cig abuse liability should be tested using these or similar procedures. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Utilizing content-knowledge questionnaires to assess study eligibility and detect deceptive responding

Background: Deceptive responding during eligibility screening presents a significant concern for assessing inclusion/exclusion criteria. This problem is compounded in settings for which biomarkers or other objective verification (e.g., urinalysis) are not feasible.Objectives: Introduce and describe content-knowledge questionnaires as an objective method for collaterally assessing study eligibility.Methods: Participants (N = 3772; 66.1% female) recruited using the crowdsourcing resource Amazon Mechanical Turk (mTurk) completed a Cannabis Knowledge Questionnaire (CKQ). The CKQ contained four-items indexing knowledge of typical cannabis costs, weights, and terminology. Self-reported cannabis use history was collected and compared to individual item and total scale scores. A separate in-laboratory assessment evaluated participants during in-person screening for cannabis, alcohol, and cocaine research protocols (N = 43).Results: Good internal consistency (α = .74) was observed. The most common correctly answered question was about dabbing (41.4%) followed by cannabis cost (37.6%), hybrid strains (36.6%), and estimated weight (29.7%). Current cannabis use was associated with large effect size increases in the rate of correct responses (RR = 3.64) as well as odds of a correct response on individual items (OR = 5.88-21.48). In the laboratory study, participants with a positive urine drug test for cannabis or those reporting lifetime regular cannabis use scored higher than those without this history (RR = 1.89-2.61).Conclusion: These findings highlight the efficiency and efficacy of including content-knowledge questionnaires for collateral assessment of study eligibility, especially when biomarkers are not possible. Future studies will be useful for extending this initial demonstration to alternative settings and substances.

A pilot investigation of the effect of electronic cigarettes on smoking behavior among opioid-dependent smokers

INTRODUCTION

Compared to the general population, smoking rates are 2-4 times higher among individuals with opioid use disorders (OUDs). These smokers also have poor long-term cessation rates, even with pharmacotherapy or other interventions. Low success rates with traditional approaches may prompt smokers with OUDs to try more novel products like electronic cigarettes (ECIGs). This pilot study was designed to examine the feasibility, acceptability, and effect of ECIGs on smoking behavior among smokers with OUD.

METHODS

Participants (N = 25) were daily smokers receiving buprenorphine/naloxone for OUD at an outpatient clinic. They were randomized to use a second-generation ECIG (0 or 18 ng/ml nicotine) ad libitum for two weeks while completing assessments via text messaging daily, and also via in-person visits at baseline, end of the two-week intervention, and a 4-week follow-up.

RESULTS

Feasibility was evidenced by high enrollment (93.9%) and retention (70.9%) rates. ECIG adherence was relatively high as measured by self-report (80.6% active, 91.7% placebo), while the average volume of liquid used per week was low (~3 ml). Both ECIG doses produced reductions in self-reported cigarettes per day that were not supported by average carbon monoxide levels. Biologically-confirmed smoking abstinence was observed in 8% of participants.

CONCLUSIONS

Preliminary results suggest that smokers with OUD are interested in using ECIGs, but their adherence may be less than ideal. Poor medication adherence rates are often observed in this disparate population, and future work should consider the use of other ECIG device types and a combination of methods to verify and quantify ECIG use.

Electronic cigarette user plasma nicotine concentration, puff topography, heart rate, and subjective effects: Influence of liquid nicotine concentration and user experience

Electronic cigarette (ECIG) nicotine delivery and other effects may depend on liquid nicotine concentration and user experience. This study is the first to systematically examine the influence of ECIG liquid nicotine concentration and user experience on nicotine delivery, heart rate, puff topography, and subjective effects. Thirty-three ECIG-experienced individuals and 31 ECIG-naïve cigarette smokers completed 4 laboratory conditions consisting of 2, 10-puff bouts (30-sec interpuff interval) with a 3.3-V ECIG battery attached to a 1.5-Ω "cartomizer" (7.3 W) filled with 1 ml ECIG liquid. Conditions differed by liquid nicotine concentration: 0, 8, 18, or 36 mg/ml. Participants' plasma nicotine concentration was directly related to liquid nicotine concentration and dependent on user experience, with significantly higher mean plasma nicotine increases observed in ECIG-experienced individuals relative to ECIG-naïve smokers in each active nicotine condition. When using 36 mg/ml, mean plasma nicotine increase for ECIG-experienced individuals was 17.9 ng/ml (SD = 17.2) and 6.9 (SD = 7.1; p < .05) for ECIG-naïve individuals. Between-group differences were likely due to longer puffs taken by experienced ECIG users: collapsed across condition, mean puff duration was 5.6 sec (SD = 3.0) for ECIG-experienced and 2.9 (SD = 1.5) for ECIG-naïve individuals. ECIG use also suppressed nicotine/tobacco abstinence symptoms in both groups; the magnitude of abstinence symptom suppression depended on liquid nicotine concentration and user experience. These and other recent results suggest that policies intended to limit ECIG nicotine delivery will need to account for factors in addition to liquid nicotine concentration (e.g., device power and user behavior). (PsycINFO Database Record

"Essentially, All Models are Wrong, but Some Are Useful": A Preliminary Conceptual Model Of Co-Occurring E-Cig and Alcohol Use

PURPOSE OF REVIEW

As prevalence rates of electronic cigarette (e-cig) use increase, researchers and clinicians should not only be paying careful attention to the direct health effects of e-cigs, but also the potential impact e-cigs may have on alcohol use behaviors. We review the current state of the literature and propose a conceptual model for the relationship between e-cig and alcohol use, including important consequences, mechanisms, and moderators of this relationship.

RECENT FINDINGS

The model is based in emerging literature examining the direct relationship between e-cig and alcohol use, as well as indirect evidence concerning potential mechanisms from research on cigarette and alcohol use. Overall, research indicates a robust relationship between e-cig and alcohol use.

SUMMARY

We suggest that a relationship between e-cig use and alcohol use could be particularly problematic, especially for adolescents and for those with or at risk for alcohol use disorders. We hope the presented conceptual model can stimulate research in this area. We make research recommendations, including the need for more methodological rigor, including improved measurement of e-cig use, and expanding research to longitudinal and experimental designs.

Advances in Behavioral Laboratory Methods that Inform Tobacco Regulatory Science: A TCORS Working Group Special Issue

Objective

The 2009 Family Smoking Prevention and Tobacco Control Act (TCA) created unprecented enabling conditions for establishing national regulatory policy that reduces the burden of public health and societal problems associated with tobacco product use. The Center for Tobacco Products (CTP), created by the FDA to implement the TCA, developed a first-of-its-kind FDA/National Institutes of Health (NIH) collaborative program to fund Tobacco Centers of Regulatory Science (TCORS).

Methods

To assist the TCORS with addressing research priorites, working groups (WGs) comprised of FDA-CTP liasions and TCORS investigators were formed. Under the direction of the Center for Evaluation and Coordination of Trainin and Research (CECTR), the TCORS WGs seek to develop tangible work products in their respective areas of focus.

Results

The focus of the behavioral pharmacology WG evolved from publishing a narrow paper on behavioral methods in electronic cigarette research to a collection of papers on advances in behavioral laboratory methods that may inform tobacco regulatory science.

Conclusion

This Special Issue contains articles that address all of the CTP research priorities and demonstrates how advances in behavioral laboratory methods made by TCORS investigators can inform FDA efforst to regulate tobacco products.