Pharmacodynamic and pharmacokinetic assessment of electronic cigarettes, combustible cigarettes, and nicotine gum: implications for abuse liability

Concurrent E-cigarette Use While Enrolled in a Smoking Cessation Program: Associations Between Frequency of Use, Motives for Use, and Smoking Cessation

INTRODUCTION

Trial evidence suggests that e-cigarettes may aid in quitting smoking, while observational studies have found conflicting results. However, many observational studies have not adjusted for important differences between e-cigarette users and non-users.

AIMS AND METHODS

We aimed to determine the association between e-cigarette use frequency and motivation to use e-cigarettes to quit smoking, and smoking cessation using data from Canada's largest smoking cessation program. Participants who completed a baseline assessment and 6-month follow-up questionnaire were divided post hoc into four groups based on their self-reported e-cigarette use during the 30 days before baseline: (1) non-users; (2) users of e-cigarettes not containing nicotine; (3) occasional users; and (4) frequent users. Occasional and frequent users were further divided into two groups based on whether they reported using e-cigarettes to quit smoking. Abstinence at 6-month follow-up (7-day point prevalence abstinence) was compared among groups.

RESULTS

Adjusted quit probabilities were significantly higher (both p < .001) for frequent baseline e-cigarette users (31.6%; 95% CI = 29.3%, 33.8%) than for non-users (25.8%; 25.3% and 26.3%) or occasional users (24.2%; 22.5% and 26.0%). Unadjusted proportions favored non-users over occasional users (p < .001), but this was not significant after adjustment (p = .06). People using e-cigarettes to quit smoking were not likelier than other users to be successful, but were likelier to report frequent e-cigarette use during follow-up.

CONCLUSIONS

Frequent baseline e-cigarette use predicted successful smoking cessation, compared to occasional and non-users. Use of e-cigarettes to quit did not predict smoking cessation but was associated with continued use during follow-up, perhaps due in part to planned transitions to e-cigarettes.

IMPLICATIONS

Prior observational studies investigating e-cigarette use for smoking cessation have found that occasional users have poorer outcomes than either frequent or non-users. Consistent with these studies, occasional users in our data also had poorer outcomes. However, after adjustment for variables associated with cessation success, we found that cessation probabilities did not differ between occasional and non-users. These findings are consistent with trial data showing the benefit of e-cigarette use among people trying to quit smoking. Results of this study suggest that differences between trials and previous observational studies may be because of unaddressed confounding in the latter.

Abuse liability of two electronic nicotine delivery systems compared with combustible cigarettes and nicotine gum from an open-label randomized crossover study

An assessment of the likelihood of use and abuse potential for new tobacco products is an important part of tobacco product regulation in the United States and abroad. This paper reports the results of a randomized, open-label, crossover clinical study that assessed factors related to product adoption and abuse liability (AL), comparing two closed electronic nicotine delivery system (ENDS) products to combustible cigarettes and nicotine gum, high- and low-AL comparator products, respectively. During an 11-day confinement period that included multiple product familiarization sessions, healthy adult smokers participated in AL test sessions to evaluate the abuse liability of each product. During these test sessions, changes in subjective measures; speed and amount of nicotine uptake; and maximum changes in physiological effects before, during, and after use of each assigned product were assessed over 4 h. Positive subjective effects measures scores such as product-liking and overall intent to use again were highest for cigarettes, followed by the Vuse ENDS, with nicotine gum consistently having the lowest scores. The PK results (Cmax and Tmax) of the Vuse ENDS products are between UB cigarettes and nicotine gum, which correlates with the subjective effects. All nicotine uptake measures for the Vuse ENDS products were lower than that of usual brand (UB) cigarettes, including peak nicotine uptake and overall nicotine uptake, and were either similar to or lower than nicotine gum. The time course of nicotine uptake after use of the ENDS was more similar to that of combustible cigarettes than nicotine gum. The results indicate that the AL of each ENDS product is lower than that of UB cigarettes and similar to that of nicotine gum.

Examination of the impact of myblu electronic nicotine delivery system e-liquid nicotine strength on self-reported measures of dependence

BACKGROUND

Greater nicotine delivery is associated with higher nicotine concentrations in electronic nicotine delivery system (ENDS) liquids. However, there is a current debate as to whether this leads to increased dependence and mitigates ENDS public health potential.

METHODS

Self-reported dependence among users of myblu ENDS containing different nicotine concentrations was examined with data from a multiwave cross-sectional survey of US young adults and adults. Questions examined responses related to dependence measures and participants' most often used myblu ENDS nicotine concentration (low: 0%, 1% and 1.2%; medium: 2%, 2.4% and 2.5%; or high: 3.6% and 4%).

RESULTS

A global general linear model using nicotine concentration, age and days myblu that was used in the past 30 revealed a significant difference in PROMIS scores among nicotine concentration groups (F = 4.07, p = 0.02). However, pairwise comparisons to examine which specific groups differed significantly from others showed no significant differences. Logistic regression demonstrated that strong past 30-day cravings to use myblu among participants using high or medium nicotine concentrations were not significantly different from those using a low concentration (ORs 0.66 [0.42, 1.03], p = 0.07 and 0.95 [0.49, 1.82], p = 0.98, respectively). Time to daily first use for high or medium nicotine concentration users was not significantly different from those using a low concentration (ORs 0.89 [0.70, 1.14], p = 0.35 and 0.84 [0.57, 1.25], p = 0.40, respectively).

CONCLUSIONS

Use of myblu ENDS with different nicotine concentrations is not associated with differing levels of dependence. Our findings contradict the notion that high ENDS e-liquid nicotine levels generate increased dependence.

An assessment of nicotine pharmacokinetics and subjective effects of the pulze heated tobacco system compared with cigarettes

Nicotine delivery and subjective effects are determinants of the ability of potentially less harmful tobacco products such as heated tobacco products (HTPs) to support adult smokers in switching away from cigarettes, and therefore to support tobacco harm reduction. This open-label, randomised, crossover, clinical study in 24 healthy adult smokers study assessed nicotine pharmacokinetics and subjective effects of the Pulze Heated Tobacco System (HTS; Pulze HTP device and three iD stick variants-Intense American Blend, Regular American Blend and Regular Menthol) compared with subjects' usual brand cigarettes (UBC). C_max and AUC_t were highest for UBC and significantly lower for each Pulze HTS variant. C_max and AUC_t were significantly higher for Intense American Blend compared with Regular American Blend, while AUC_t was significantly higher for Intense American Blend compared with Regular Menthol. Median T_max was lowest (i.e., nicotine delivery was fastest) for subjects' usual brand cigarettes and similar across the iD stick variants, although no between-product differences were statistically significant. All study products reduced urges to smoke; this effect was greatest for cigarettes although this was not statistically significant. Product evaluation scores for each Pulze HTS variant in the domains of 'satisfaction', 'psychological reward' and 'relief' were similar, and lower than those for UBC. These data demonstrate that the Pulze HTS effectively delivers nicotine and generates positive subjective effects, including satisfaction and reduced urge to smoke. This supports the conclusion that the Pulze HTS may be an acceptable alternative to cigarettes for adult smokers while having a lower abuse liability than cigarettes.

Part two: an unblinded, parallel, randomized study to assess nicotine pharmacokinetics of four Vuse Solo ENDS flavors in smokers

We report the findings from a randomized, parallel study designed to evaluate nicotine pharmacokinetics (PK) following 10 min of ad libitum use of electronic nicotine delivery system (ENDS) in four flavor variants. Subjects were randomized an investigational product (IP) and blood samples were collected for PK assessments during a test session. Primary endpoints were baseline-adjusted values of maximum plasma nicotine concentration (C_max) and area under the nicotine concentration-vs-time curve up to 60 min (AUC_nic0-60). Baseline-adjusted mean C_max ranged from 6.53 to 8.21 ng/mL, and mean AUC_nic0-60 ranged from 206.87 to 263.52 ng min/mL for all ENDS IPs. Results of geometric mean C_max and AUC_nic0-60 values were within 95% confidence intervals (CI) among the ENDS IP flavor variants tested.

Part one: abuse liability of Vuse Solo (G2) electronic nicotine delivery system relative to combustible cigarettes and nicotine gum

Abuse liability (AL) of electronic nicotine delivery systems (ENDS) is relevant as the category increases in popularity as a potentially less-harmful alternative to cigarette smoking. AL assessments are important to the FDA in determining if a new product is appropriate for the protection of public health. This paper reports the results for Vuse Solo (G2 cartridge design) compared to high and low AL-comparators evaluated in an open-label, randomized crossover confinement AL study. The confinement design was adapted from previous ambulatory studies of Vuse Solo (G1 cartridge design) and included product familiarization sessions before each four-hour test session in which subjective measures, nicotine pharmacokinetics (PK), and physiological endpoints were assessed following a single 10-min ad libitum product use session. Product liking, intent to use again, suppression of urge to smoke, and nicotine PK were lower after use of Vuse Solo compared to cigarettes and higher after use of Vuse Solo compared to nicotine gum. No significant differences in blood pressure or heart rate were observed between the products pre- to post-product use. These data reinforce previous research and provide the scientific evidence to support regulatory decisions demonstrating that Vuse Solo has an AL profile lower than that of combustible cigarettes but higher than that of nicotine gum and, therefore, may be a suitable replacement for cigarette smoking for some adult smokers.

Part three: a randomized study to assess biomarker changes in cigarette smokers switched to Vuse Solo or Abstinence

Biomarkers of exposure (BoE) can help evaluate exposure to combustion-related, tobacco-specific toxicants after smokers switch from cigarettes to potentially less-harmful products like electronic nicotine delivery systems (ENDS). This paper reports data for one (Vuse Solo Original) of three products evaluated in a randomized, controlled, confinement study of BoE in smokers switched to ENDS. Subjects smoked their usual brand cigarette ad libitum for two days, then were randomized to one of three ENDS for a 7-day ad libitum use period, or to smoking abstinence. Thirteen BoE were assessed at baseline and Day 5, and percent change in mean values for each BoE was calculated. Biomarkers of potential harm (BoPH) linked to oxidative stress, platelet activation, and inflammation were also assessed. Levels decreased among subjects randomized to Vuse Solo versus Abstinence, respectively, for the following BoE: 42-96% versus 52-97% (non-nicotine constituents); 51% versus 55% (blood carboxyhemoglobin); and 29% versus 96% (nicotine exposure). Significant decreases were observed in three BoPH: leukotriene E4, 11-dehydro-thromboxane B2, and 2,3-dinor thromboxane B2 on Day 7 in the Vuse Solo and Abstinence groups. These findings show that ENDS use results in substantially reduced exposure to toxicants compared to smoking, which may lead to reduced biological effects.

Nicotine Delivery and Pharmacokinetics of an Electronic Cigarette Compared With Conventional Cigarettes in Chinese Adult Smokers: A Randomized Open-Label Crossover Clinical Study

INTRODUCTION

To evaluate the nicotine pharmacokinetics of a commercial electronic cigarette (e-cigarette) relative to conventional cigarettes in Chinese adult smokers.

AIMS AND METHODS

A randomized, open-label, crossover clinical study was conducted on 23 healthy adult Chinese smokers. In two sessions, subjects used either the e-cigarettes with 30 mg/g nicotine in e-liquid or conventional cigarettes of a given brand, at one puff every 30 seconds for a total of 10 puffs. Blood samples were collected at specified time points for 4 hours after the first puff. Subjective effects on desire-to-smoke and physiological parameters such as heart rate and oxyhemoglobin saturation levels were also examined before and after using the two products.

RESULTS

The baseline-adjusted maximum nicotine concentration (Cmax-BL), time-to-peak nicotine concentration (Tmax), and nicotine absorption rate (Cmax-BL divided by Tmax) were found to be similar for the e-cigarette versus those of conventional cigarettes (p > .05). Total nicotine exposure measured as the area-under-curve (AUC0-t-BL) was significantly lower for the e-cigarette relative to that of conventional cigarettes. In addition, the subjects found that e-cigarettes were well tolerated under controlled puffing conditions.

CONCLUSIONS

The test e-cigarettes achieved similar nicotine delivery and pharmacokinetic profiles to those of the comparator cigarettes, indicating that this e-cigarette could be a potential alternative to conventional cigarettes for those adult smokers.

IMPLICATIONS

There are no data in the published literature on the nicotine pharmacokinetics of e-cigarettes in Chinese smokers. To the best of our knowledge, this is the first study to evaluate the nicotine delivery and pharmacokinetic profile of a commercial e-cigarette brand compared with conventional cigarettes in Chinese adult smokers. After the use of test e-cigarettes, nicotine delivery and pharmacokinetic profile were similar to those of conventional cigarettes in Chinese adult smokers.

Unintentional fatal toxicity due to nicotine chewing gum: A case report

RATIONALE

Since tobacco contains numerous harmful substances, besides nicotine, which is addictive, smoking cessation products and tobacco alternatives, such as electronic (e-) cigarettes, nicotine chewing gums, and patches, are being widely used. Nicotine gums are consumed orally. The nicotine from the gum is absorbed at a slower rate than that from e-cigarettes, and the former remains in the bloodstream for a longer period. In addition, the maximum number of daily doses is high, and it can be purchased without a doctor's prescription in many countries.

PATIENT CONCERNS

A 29-year-old male patient consumed 5 2-mg nicotine gums at a time, twice a day, for 4 days (total amount: 70 mg). However, he visited the emergency unit with the chief complaint of involuntary limb movements after consuming an additional 15 gums 3 hour before the visit. At admission, his consciousness was clear, although 2 hour later, he experienced sudden loss of consciousness with worsening hypoxia and respiratory acidosis.

DIAGNOSIS

The patient's vital signs were stable at the time of admission, and blood test results showed no specific findings other than a white blood cell count of 14,800/µL, lactate level of 6.4 mmol/L, and prolactin level of 119.02 ng/mL. In addition, chest radiography and head computed tomography scans showed no acute phase abnormalities. Two hours later, he experienced loss of consciousness and respiratory failure, and the results of blood tests performed at this time showed that his blood cotinine level was 3491 ng/mL.

INTERVENTIONS

Supportive treatment, including endotracheal intubation followed by mechanical ventilation, was provided.

OUTCOME

The patient's vital signs stabilized 3 days after treatment, and his consciousness and respiratory status had improved; therefore, mechanical ventilation was stopped. His condition was stable for the next 2 days, and he was discharged on the fifth day.

LESSONS

Acute respiratory exacerbation due to nicotine poisoning (from levels exceeding the lethal dose of 30-60 mg) was observed, although the gums were consumed over several days. Patients with nicotine poisoning may show acute respiratory failure and should be monitored carefully. Further studies are required to determine the toxic effects of nicotine replacement therapies.

Novel rapid-acting sublingual nicotine tablet as a cigarette substitution strategy

RATIONALE

Current nicotine replacement products provide a much slower onset of nicotine delivery than cigarettes, and hence are only marginally effective at supplanting cigarette smoking. Therefore, more effective forms of nicotine replacement are needed.

OBJECTIVES

This initial investigation characterized the pharmacokinetic (PK) and subjective effects of a novel sublingual (SL) nicotine tablet designed to deliver nicotine more rapidly to the bloodstream of smokers.

METHODS

Study 1 (N = 6) characterized the pharmacokinetics of a 2 mg nicotine SL tablet in comparison to an FDA-approved, marketed 2 mg nicotine lozenge. Study 2 (N = 24) assessed subjective responses of smokers to a single use of a 1 mg and 2 mg SL tablet.

RESULTS

Study 1 found that the time to maximum blood nicotine concentrations was significantly shorter for the SL tablet (14 min) than for the lozenge (82 min), and the initial rate of nicotine absorption was higher (0.4 ng/mL*min vs. 0.0 ng/mL*min), supporting the hypothesis that the SL tablet delivered nicotine more rapidly. Study 2 found that participants reported immediate relief of nicotine withdrawal symptoms after tablet administration, and craving reduction after the 2 mg tablet approached the degree reported for their usual brands of cigarettes (4.2 vs. 4.6 on a 7-point scale). Other subjective responses showed the tablet to be an appealing alternative to smoking.

CONCLUSIONS

The novel SL tablet studied shows promise as a nicotine substitution strategy for tobacco harm reduction and smoking cessation treatment. Additional studies are warranted to further investigate the potential of this new approach.

An abuse liability assessment of the glo tobacco heating product in comparison to combustible cigarettes and nicotine replacement therapy

Tobacco heating products (THPs) have reduced emissions of toxicants compared with cigarette smoke, and as they expose user to lower levels than smoking, have for a role to play in tobacco harm reduction. One key concern of Public Health is that new tobacco and nicotine products should not be more addictive than cigarettes. To assess their abuse liability, we determined nicotine pharmacokinetics and subjective effects of two THPs compared with conventional cigarettes and a nicotine replacement therapy (Nicotine inhaler). In a randomised, controlled, open-label, crossover study healthy adult smokers used a different study product in a 5 min ad libitum use session in each of four study periods. Product liking, overall intent to use again, urge for product and urge to smoke questionnaires were utilised to assess subjective effects. Nicotine uptake was greater for the cigarette (C_max = 22.7 ng/mL) than for either THP (8.6 and 10.5 ng/mL) and the NRT (2.3 ng/mL). Median T_max was significantly longer for the NRT (15.03 min) than for the tobacco products (4.05–6.03 min). Product liking and overall intent to use again was highest for the cigarette, and higher for the THPs than the NRT. Urge to smoke was reduced more by the cigarette than by the other three products. Urge to use the THPs was greater than the NRT. These findings suggest that the abuse liability of the THPs lies between that of subjects usual brand cigarettes and the NRT.

Trajectories of Nicotine Use Leading to Dual and Cyclical Tobacco Product Use in Young Adults

INTRODUCTION

Young adult never-smokers who vape are at elevated risk of initiating cigarettes, while young adults who smoke often begin vaping to substitute or reduce cigarette use. Reasons underlying different use patterns of tobacco products are not well-understood.

AIMS AND METHODS

We conducted 1-on-1 qualitative interviews with young adults (N = 62) who vape in Los Angeles, California from June 2018 to June 2019. Participants were 18-25 years old (79% male; racially/ethnically diverse) and self-reported vaping ≥1x/week. We used a semi-structured interview guide and applied thematic analysis method to analyze data.

RESULTS

Young adults initiated vaping due to peer socialization and e-liquid flavor novelty. They often reported vaping (after first smoking) due to a belief that e-cigarettes are healthier, social pressure to quit smoking, and convenience of use. Participants reported smoking (after first vaping) when traveling outside of the United States where vaping products were less accessible, and cigarettes were normative. Many of the personal narratives described patterns of dual and cyclical use, which was often attributed to nicotine dependence and cost, or described as dependent upon the current environment (eg, at a party).

CONCLUSIONS

The current study characterizes nicotine use trajectories and reasons why young adults vape, and smoke cigarettes. Dual and cyclical use of both e-cigarettes and cigarettes was common; this pattern of use should be considered in policy and prevention work to address nicotine dependence among young people.

IMPLICATIONS

We display findings from the current study in a model depicting common trajectories of nicotine use, along with reasons for initiation, transitions between products, and dual/cyclical e-cigarette and combustible cigarette use.

A randomised, crossover, clinical study to assess nicotine pharmacokinetics and subjective effects of the BIDI® stick ENDS compared with combustible cigarettes and a comparator ENDS in adult smokers

BACKGROUND

Nicotine pharmacokinetic assessments of electronic nicotine delivery systems (ENDS) are crucial to understand their ability to provide an alternative to cigarette smoking. Subjective effects data also strongly contribute to this understanding. The BIDI® Stick is a disposable ENDS product which contains 59 mg/ml nicotine benzoate salt and various flavours.

METHODS

In this study, we assessed nicotine pharmacokinetics and subjective effects of 6 flavour variants of BIDI® Stick ENDS in adult smokers, compared to cigarettes and a comparator ENDS product. During each of eight study visits, 18 volunteer smoker subjects randomly used one of either their usual brand (UB) of cigarette, a BIDI® Stick ENDS, or a comparator ENDS (JUUL 59 mg/ml nicotine with Virginia Tobacco flavour), during both controlled (10 puffs, 30 s apart) and ad libitum (60 min) puffing sessions. Blood samples were collected at various time points and subjective effects questionnaires were administered.

RESULTS

Mean [SD] plasma nicotine Cmax 0-120 was not significantly different between BIDI® Stick ENDS with any flavour (range 15.3 [9.90] ng/ml for BIDI® Stick Winter to 17.6 [9.00] ng/ml for BIDI® Stick Classic) and UB cigarettes (16.2 [9.17] ng/ml). Mean [SD] AUC0-120 (range 569.7 [327.29] to 628.6 [408.99]  min*ng/ml for BIDI® Stick ENDS and 747.1 [325.48]  min*ng/ml for UB cigarettes) and median Tmax 0-120 (range 5-7 min for all BIDI® Stick ENDS and UB cigarettes) values were also not significantly different between BIDI® Stick ENDS and UB cigarettes, while subjective effects measures were also similar between BIDI® Stick ENDS and UB cigarettes. Mean [SD] plasma nicotine Cmax 0-120, AUC0-120, and median Tmax 0-120 were 6.8 [4.13] ng/ml, 243.6 [179.04] min*ng/ml, and 5 min, respectively, for JUUL ENDS. These values were significantly different compared with those for all BIDI® Stick ENDS and UB cigarettes for both Cmax 0-120 and AUC0-120 but not for Tmax 0-120.

CONCLUSIONS

BIDI® Stick ENDS delivered nicotine to users comparably to their UB combustible cigarette and higher than JUUL ENDS, and also elicited similar subjective effects such as satisfaction and relief. Thus, the BIDI® Stick ENDS may be a satisfying alternative to cigarettes among current smokers and may support their transitioning away from cigarette smoking.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier number NCT05072925).

Cigarette Smoke Extract, but Not Electronic Cigarette Aerosol Extract, Inhibits Monoamine Oxidase in vitro and Produces Greater Acute Aversive/Anhedonic Effects Than Nicotine Alone on Intracranial Self-Stimulation in Rats

Conventional tobacco cigarettes appear to have greater abuse liability than non-combusted products such as electronic cigarettes (ECs) and nicotine replacement therapy (NRT). This may be due to the higher levels of behaviorally active non-nicotine constituents [e.g., monoamine oxidase (MAO) inhibitors such as β-carbolines] in cigarette smoke (CS) compared to non-combusted products. To evaluate this hypothesis, the current studies compared the relative abuse liability of CS and EC aerosol extracts containing nicotine and a range of non-nicotine constituents to that of nicotine alone (NRT analog) using intracranial self-stimulation (ICSS) in rats. Effects of formulations on brain MAO activity in vitro and ex vivo were also studied to evaluate the potential role of MAO inhibition in the ICSS study. CS extract contained higher levels of several behaviorally active non-nicotine constituents (e.g., the β-carbolines norharmane and harmane) than EC extract. Nicotine alone reduced ICSS thresholds at a moderate nicotine dose, suggesting a reinforcement-enhancing effect that may promote abuse liability, and elevated ICSS thresholds at a high nicotine dose, suggesting an aversive/anhedonic effect that may limit abuse liability. CS extract elevated ICSS thresholds to a greater degree than nicotine alone at high nicotine doses. Effects of EC extract on ICSS did not differ from those of nicotine alone. Finally, CS extract significantly inhibited MAO-A and MAO-B activity in vitro, whereas EC extract and nicotine alone did not. None of the formulations inhibited MAO measured ex vivo. These findings indicate greater acute aversive/anhedonic effects for CS extract compared to nicotine alone, suggesting lower abuse liability. Although confirmation of our findings using other dosing regimens, preclinical addiction models, and tobacco product extracts is needed, these findings suggest that the centrally-mediated effects of MAO inhibitors and other non-nicotine constituents may not account for the greater abuse liability of cigarettes compared to non-combusted products. Nonetheless, identifying the specific constituent(s) mediating the effects of CS extracts in this study could help clarify mechanisms mediating tobacco addiction and inform FDA product standards.

A randomised study to assess the nicotine pharmacokinetics of an oral nicotine pouch and two nicotine replacement therapy products

Nicotine replacement therapies (NRTs) are intended for short-term use to help cigarette smokers to quit. Some smokers find NRTs ineffective or seek a more satisfactory source of nicotine. Tobacco-free oral nicotine pouch (NP) products have emerged as a potential reduced risk product compared with cigarettes and other tobacco products. In a randomised crossover clinical study, thirty-four healthy adult smokers were enrolled and their nicotine C_max and AUC_0-T determined for three 4 mg nicotine products (NP, gum, lozenge) under fasting conditions. The NP, lozenge and gum mean C_max values were 8.5, 8.3 and 4.4 ng/mL, AUC_0-T values were 30.6, 31.5 and 14.3 ng*h/mL, respectively. The NP showed similar nicotine bioavailability to the lozenge (p = 0.6526 (C_max), p = 1.0000 (AUC_0-T)), and superior bioavailability to the gum (p  < 0.0001 for C_max and AUC_0-T). Compared with the lozenge, the NP demonstrated greater product satisfaction with a higher number of positive responses to subjective satisfaction questions. All products were judged to be well-tolerated; the incidence of minor adverse events was lower for the NP (18.2%) than the lozenge (33.3%) or gum (18.8%). In summary, NPs may provide smokers with a more satisfying alternative nicotine source as compared to the reference NRTs.

Study Registry/Registered Trial No: ISRCTN/ISRCTN65708311.

Reappraising Choice in Addiction: Novel Conceptualizations and Treatments for Tobacco Use Disorder

The introduction of alternative nicotine and tobacco products (such as e-cigarettes, heat-not-burn devices, nicotine pouches) warrants an updated framework from which to conceptualize tobacco use disorder (TUD). The following review provides considerations for TUD within the context of novel products. Historically, the tobacco industry falsely claimed that cigarettes were not addictive or harmful and that those who smoked simply chose to do so. This generated an inaccurate lay perception that smoking is a free or informed choice. Research on nicotine pharmacology demonstrates the powerful addictive potential of nicotine, which is shaped by dose, speed of delivery, and other constituents generated. In addition, non-pharmacologic reinforcers motivate and maintain tobacco use behaviors for both traditional cigarettes and novel products. The negative consequences of combustible tobacco use are well known; however, these outcomes may differ for alternative products. Strategies used for combustible product cessation may be adapted for novel products, and treatment recommendations for TUD should be made within the context of a harm reduction framework wherein alternative product use may be the desired outcome. Providers must therefore be willing to modify their perceptions of products and treatment recommendations accordingly. Better public health outcomes are accomplished through promotion of abstinence from combustible smoking. For those who cannot wean from nicotine entirely, switching to less risky modes of delivery might be a secondary goal, with an eventual aim of stopping use of the alternative product. Implications: Given the advent of novel, alternative tobacco products, tobacco use disorder (TUD) must be conceptualized within a contemporary framework that includes harm reduction and alternative outcomes. The unique contributions of nicotine pharmacology, non-pharmacologic reinforcers, and consequences of use can be used to inform treatments for TUD with the ultimate goal of improving the health of individuals who use tobacco.

Study protocol: evaluation of the addictive potential of e-cigarettes (EVAPE): neurobiological, sociological, and epidemiological perspectives

BACKGROUND

Tobacco use is the largest preventable cause of diseases and deaths; reducing tobacco intake is, therefore, an urgent public health goal. In recent years, e-cigarettes have been marketed as a 'healthier' alternative to tobacco smoking, whilst product features have evolved tremendously in the meantime. A lively scientific debate has developed regarding the potential benefits and risks of e-cigarettes although, surprisingly, there are few studies investigating the addictive potential of nicotine-containing e-cigarettes. The present work comprises three work packages investigating the addictive potential of e-cigarettes from different perspectives: (1) the neurobiological addictive potential of e-cigarettes; (2) the experience and perception of dependence symptoms among users of e-cigarettes in a social context; and (3) the epidemiological perspective regarding factors influencing the potential for dependence.

METHODS

Work package I: the neurobiological study will investigate the key elements of addiction in e-cigarettes compared to tobacco cigarettes using neurobiological and neuropsychological correlates associated with craving, incentive motivation, cue reactivity and attentional bias. Work package II: the sociological study part examines self-reports on the experience and perception of dependence symptoms in a social context, using focus group interviews and the analysis of posts in online discussion forums on e-cigarettes. Work package III: the epidemiological study part focuses on tolerance development and the role of psychosocial and product factors by analyzing longitudinal data from the International Tobacco Control Policy Evaluation Project (ITC).

DISCUSSION

The present study offers a chosen mix of three methodological approaches, thereby comprehensively examining core symptoms of positive and negative reinforcement in addiction. Whether e-cigarettes are as reinforcing and addictive as combustible tobacco cigarettes is an important public health issue with implications for prevention and treatment programs.

TRIAL REGISTRATION

Work package I: Registered at clinicaltrials.gov/ct2/show/NCT04772014. Work package II: Registered at OSF Registries: https://osf.io/dxgya (2021, January 14).

Characterization of the Abuse Potential in Adult Smokers of a Novel Oral Tobacco Product Relative to Combustible Cigarettes and Nicotine Polacrilex Gum

Novel noncombustible tobacco products offer adult smokers (ASs) alternatives to combustible cigarettes lower on the continuum of risk; however, the abuse potential of such products has not been well studied. The objective of this study was to evaluate the abuse potential of 2 chewable tobacco‐derived nicotine containing products, VERVE Chews Blue Mint (test 1) and Green Mint (test 2), in ASs compared with own‐brand cigarettes (CIGS) and nicotine polacrilex gum (GUM) using subjective measures and nicotine pharmacokinetics. ASs used the test products during a 5‐day at‐home trial prior to completing an in‐clinic 4‐period randomized crossover study. During the study ASs used test products, CIGS, and GUM once on separate days. Responses to Tobacco/Nicotine Withdrawal and Direct Effects of Product questionnaires were documented, and blood samples were collected to assess nicotine pharmacokinetics during each product use. Nicotine pharmacokinetic parameters (C_max and AUC) were statistically significantly lower with use of test products compared with CIGS and statistically significantly higher compared with GUM. No appreciable differences were noted between the 2 flavors for any of the end points measured. Reductions in maximum urge to smoke and maximum responses to the question “Is the Product ‘Pleasant’ Right Now?” for the test products were statistically significantly lower than CIGS but comparable to GUM. Similar results were observed for responses to other items in the 2 questionnaires. The test products, under the conditions of this study, carry lower abuse potential than own‐brand cigarettes and similar to nicotine polacrilex gum.

Nicotine pharmacokinetics of electronic cigarettes: A pooled data analysis from the literature

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Evaluating the pharmacokinetics of nicotine absorption from electronic cigarettes.

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Nicotine absorption into the blood is influenced by several factors.

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These include e-liquid composition, user behavior and device characteristics.

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Any regulation of nicotine levels in e-liquids should reflect this heterogeneity.

Several regulatory initiatives around the world restrict the amount of nicotine permitted in electronic cigarette liquids in an attempt to reproduce the nicotine delivery of combusted tobacco products, such as cigarettes, and or reduce the risk of consumers absorbing too much nicotine into their body at one time. Such an approach, however, assumes that (i) there is a strong correlation between the levels of nicotine in electronic cigarette liquids and nicotine intake into the body and (ii) that this correlation holds true across the various different types of electronic cigarette devices currently available on the market. In order to test these hypotheses, this study examines the available scientific literature on nicotine intake from electronic cigarettes, as measured by levels in the blood. Analysis of the published data reveals that nicotine absorption into the body is influenced by a combination of many factors, including electronic cigarette liquid composition, user behavior and device characteristics. Notably, it was observed that open-tank (refillable) electronic cigarettes, which often enable users to vary device power, can deliver high nicotine levels to consumers, sometimes at greater doses than a conventional tobacco cigarette, even at the lower nicotine liquid concentrations typically available. For electronic cigarettes to be viable alternative choices to smoking, they should provide consumers with an equally satisfying experience, including in terms of nicotine absorption into the body. Therefore, any regulation seeking to restrict the amount of nicotine in electronic cigarette liquids should take all the factors influencing nicotine intake into account.

Abuse liability assessment of the JUUL system in four flavors relative to combustible cigarette, nicotine gum and a comparator electronic nicotine delivery system among adult smokers

BACKGROUND

The abuse liability of the JUUL System (JS) in four flavors were evaluated compared to combustible cigarettes, nicotine gum, and a comparator electronic nicotine delivery system (ENDS) with pharmacokinetics (PK) and subjective effects.

METHODS

Adult smokers (N = 66; 50.0 % female; mean age = 41.1; 63.6 % white) completed a 7-arm within-subjects cross-over product-use study while confined to a clinical laboratory. Participants used JS in four flavors (Virginia Tobacco, Mango, Mint, Creme, [5.0 % nicotine; 59 mg/mL]), their usual brand (UB) cigarette, a comparator ENDS (VUSE Solo; 4.8 % nicotine, tobacco-flavor), and mint nicotine gum (4 mg) under controlled use conditions. After each product use, nicotine PK and subjective effects were assessed.

RESULTS

Maximum plasma nicotine levels (Cmax-BL), rate of plasma nicotine rise, overall nicotine exposure (AUC0-60-BL), and subjective liking and satisfaction of JS were significantly lower than UB cigarettes. These parameters were generally greater for JS than nicotine gum; the comparator ENDS was somewhat lower but within the range of JS. Nicotine PK did not differ among the Mint, Mango, and Virginia Tobacco JS flavors. Mint and Mango were rated as more satisfying than Virginia Tobacco and Creme.

CONCLUSIONS

Controlled use of JS among adult smokers resulted in nicotine delivery, product liking, and satisfaction that were less than that of combustible cigarettes but generally greater than nicotine gum. These results support the conclusion that JS has lower abuse liability than combustible cigarettes, higher abuse liability than nicotine gum, and may provide sufficient nicotine delivery and satisfying effects to support substitution for combustible cigarettes among adult smokers.

The role of subjective responses in electronic cigarette uptake and substitution in adult smokers

BACKGROUND

While a majority of cigarette smokers who use electronic cigarettes (e-cigarettes) choose to continue using cigarettes, completely switching to e-cigarettes is necessary to reduce tobacco-related harm. Whether specific subjective responses to e-cigarettes are associated with extent of smoking reduction and complete switching from cigarettes to e-cigarettes is unclear. This study determined whether initial subjective responses to e-cigarettes related to the successful substitution of e-cigarettes for cigarettes and extent of cigarette and e-cigarette use.

METHODS

Adult cigarette smokers (N = 58) uninterested in quitting were asked to completely substitute their cigarettes with an e-cigarette (Vuse Solo) for 8 weeks. At week 1, subjective responses to e-cigarettes were measured using the Product Evaluation Scale and Drug Effects/Liking Survey. A Poisson regression examined whether any of these initial subjective responses were associated with smoke-free days, e-cigarette puffs, and cigarettes smoked between weeks 6 and 8 after adjustment for potential confounders. A logistic regression examined the relationship between subjective measures and exhaled carbon monoxide (CO) verified 7-day abstinence at week 8 after adjustment for potential confounders.

RESULTS

Following Holm's p-value adjustment, e-cigarette liking and desire were associated with increased e-cigarette use (adjusted p < 0.01) and decreased cigarette use (adjusted p < 0.05). Measures of psychological reward and drug liking were associated with 7-day abstinence, however this association was no longer significant following p-value adjustment.

CONCLUSIONS

Initial subjective responses were related to cigarette and e-cigarette use at weeks 6-8, but not smoke-free days or CO-verified 7-day abstinence.

Free Radical, Carbonyl, and Nicotine Levels Produced by Juul Electronic Cigarettes

INTRODUCTION

Free radicals and carbonyls produced by electronic cigarettes (e-cigs) have the potential to inflict oxidative stress. Recently, Juul e-cigs have risen drastically in popularity; however, there is no data on nicotine and oxidant yields from this new e-cig design.

METHODS

Aerosol generated from four different Juul flavors was analyzed for carbonyls, nicotine, and free radicals. The e-liquids were analyzed for propylene glycol (PG) and glycerol (GLY) concentrations. To determine the effects of e-liquid on oxidant production, Juul pods were refilled with nicotine-free 30:70 or 60:40 PG:GLY with or without citral.

RESULTS

No significant differences were found in nicotine (164 ± 41 µg/puff), free radical (5.85 ± 1.20 pmol/puff), formaldehyde (0.20 ± 0.10 µg/puff), and acetone (0.20 ± 0.05 µg/puff) levels between flavors. The PG:GLY ratio in e-liquids was ~30:70 across all flavors with GLY being slightly higher in tobacco and mint flavors. In general, when Juul e-liquids were replaced with nicotine-free 60:40 PG:GLY, oxidant production increased up to 190% and, with addition of citral, increased even further.

CONCLUSIONS

Juul devices produce free radicals and carbonyls, albeit, at levels substantially lower than those observed in other e-cig products, an effect only partially because of a low PG:GLY ratio. Nicotine delivery by these devices was as high as or higher than the levels previously reported from cigarettes.

IMPLICATIONS

These findings suggest that oxidative stress and/or damage resulting from Juul use may be lower than that from cigarettes or other e-cig devices; however, the high nicotine levels are suggestive of a greater addiction potential.

Single- and cross-commodity delay discounting of money and e-cigarette liquid in experienced e-cigarette users

BACKGROUND

Delay discounting (DD) research has improved our understanding of important behavioral processes associated with tobacco use. Little research has explored DD among e-cigarette users, and these studies have exclusively examined money as the only available commodity. This secondary analysis of a laboratory study explored discounting for money and e-liquid among e-cigarette users using two single-commodity discounting (SCD) tasks and one cross-commodity discounting (CCD) task. A secondary goal was to explore the extent to which results from the SCD and CCD tasks were correlated to each other and with measures of e-cigarette use.

METHODS

E-cigarette users (N = 27) completed two SCD tasks and one CCD task. The SCD tasks assessed choices between various amounts of either money now versus money later (M-M) or e-liquid now versus e-liquid later (mL-mL). The CCD task assessed choices between e-liquid now versus money later (mL-M). Discounting results were compared using logk and AUClog.

RESULTS

Discounting was greatest in the mL-mL task, followed by the M-M task, and then the mL-M task. AUClog and logk were significantly correlated across all discounting tasks. Attempts to quit vaping was positively associated with logk and negatively associated with AUClog and in both SCD tasks.

CONCLUSIONS

E-cigarette users discount e-liquid more than money in a SCD task. However, when the two commodities, money and e-liquid (CCD), are compared the substance of abuse is discounted to a lesser extent. Interventions that provide alternative reinforcers to compete with the reinforcing effects of nicotine intake may be especially indicated for treating e-cigarette dependence.

Impact of Nicotine Replacement and Electronic Nicotine Delivery Systems on Fetal Brain Development

Maternal tobacco smoking during pregnancy remains a major public health issue. The neurotoxic properties of nicotine are associated with fetal neurodevelopmental disorders and perinatal morbimortality. Recent research has demonstrated the effects of nicotine toxicity on genetic and epigenetic alterations. Smoking cessation strategies including nicotine replacement therapy (NRT) and electronic nicotine delivery systems (ENDS) show lack of clear evidence of effectiveness and safety in pregnant women. Limited trials using randomized controls concluded that the intermittent use formulation of NRT (gum, sprays, inhaler) in pregnant women is safe because the total dose of nicotine delivered to the fetus is less than continuous-use formulations (transdermal patch). Electronic nicotine delivery systems (ENDS) were hyped as a safer alternative during pregnancy. However, refill liquids of ENDS are suspected to be cytotoxic for the fetus. Animal studies revealed the impact of ENDS on neural stem cells, showing a similar risk of pre- and postnatal neurobiological and neurobehavioral disorders to that associated with the exposure to traditional tobacco smoking during early life. There is currently no clear evidence of impact on fetal brain development, but recent research suggests that the current guidelines should be reconsidered. The safety of NRT and ENDS is increasingly being called into question. In this review, we discuss the special features (pharmacodynamics, pharmacokinetics, and metabolism) of nicotine, NRT, and ENDS during pregnancy and postnatal environmental exposure. Further, we assess their impact on pre- and postnatal neurodevelopment.

Electronic Cigarette Use and Related Factors among Active Duty Service Members in the U.S. Military

Introduction

Electronic cigarettes (e-cigarettes) are increasingly used in the U.S.A. by young people. As young adults serve as the primary recruiting pool for military, active duty service members in military may be susceptible to using e-cigarettes. However, factors related to e-cigarette use in military population have rarely been studied. We aimed to identify factors associated with e-cigarette use and factors related to duration of use among active duty service members.

Materials and Methods

Subjects (N = 2,467) from Fort Bragg Army Base, North Carolina and Lackland Air Force Base, Texas completed a self-administered questionnaire during July 2015 to May 2016 time frame. The questionnaire collected data on demographic and military characteristics, tobacco use (including e-cigarette use) and other information. Stepwise logistic regression was performed to identify significant factors associated with e-cigarette use. Stepwise linear regression was performed to identify factors associated with duration of use.

Results

A total of 356 (14.4%) study participants reported ever use of e-cigarettes. There was no significant difference in prevalence of use between the two military installations (15.6% at Fort Bragg vs. 13.2% at Lackland, P = 0.097). Increased use of e-cigarettes was associated with young age (20–24 years old) (OR = 1.98, 95% CI = 1.22–3.22), enlisted military rank (E1–E4: OR = 2.45, 95% CI = 1.36–4.40; E5–E9: OR = 1.88, 95% CI = 1.10–3.21), low perception of harm (OR = 5.18, 95% CI = 3.65–7.34), former (OR = 9.12, 95% CI = 6.29–13.22) and current (OR = 13.24, 95% CI = 9.22–19.02) cigarette smoking, and former smokeless tobacco use (OR = 2.07, 95% CI = 1.33–3.22), former (OR = 2.62, 95% CI = 1.42–4.85) and current (OR = 2.82, 95% CI = 1.82–4.37) cigar or pipe smoking. However, serving mainly in combat unit during deployment was associated with decreased odds of use (OR = 0.57, 95% CI = 0.34–0.97). Among e-cigarette users, the number of years using e-cigarettes was significantly longer among the participants with lower perception of harm than those with higher perception of harm (0.82 vs. 0.22, P &lt; 0.001), and the duration was longer among subjects who used e-cigarette with nicotine than those without nicotine (0.79 vs. 0.49, P = 0.003). Finally, reasons for use differed markedly by cigarette smoking status. Never smokers used e-cigarette for the taste or flavor, while cigarette smokers used e-cigarette to help quit tobacco or reduce tobacco use.

Conclusion

Young age, lower military ranks, other tobacco use, and low perception of harm were associated with increased odds of using e-cigarettes, while serving in combat unit was associated with decreased odds of use in active duty service members. Low harm perception and using nicotine-containing e-cigarettes were associated with long duration of use. The reasons for using e-cigarettes differed by cigarette smoking status. Our study provides clues for future hypothesis-driven studies.

Abuse liability assessment of an electronic cigarette in combustible cigarette smokers

Under certain conditions, electronic cigarettes (e-cigs) can deliver nicotine to and suppress tobacco abstinence symptoms in cigarette smokers. Growing popularity of e-cigs raises abuse liability concerns. This study's purpose was to compare the abuse liability of an e-cig (1.5 Ohm, 3.3 V) filled with 36 mg/mL or 0 mg/mL nicotine to an Food and Drug Administration (FDA)-approved nicotine inhaler (IN) and participants' own brand (OB) of cigarettes. Smokers (N = 24) completed four sessions in which they completed the multiple-choice procedure, and plasma nicotine concentration and subjective effects were measured. Mean (SD) multiple-choice procedure crossover point was $0.87 (1.0) for the 36-mg/mL nicotine e-cig and $0.96 (1.2) for the 0-mg/mL e-cig, significantly higher than the IN mean of $0.32 (0.6) but significantly lower than the OB cigarette mean of $1.42 (1.4). Ten puffs from an own-brand cigarette increased mean plasma nicotine concentration from 3.55 (2.8) to 13.64 (9.8) ng/mL, as compared to an increase from 3.16 (1.8) to 8.51 (5.4) ng/mL for the 36-mg/mL e-cig. The 36-mg/mL e-cig reduced nicotine abstinence symptoms more than the 0-mg/mL e-cig, and both e-cigs were rated as more reinforcing than the inhaler but less reinforcing than participants' OB cigarettes (ps < .05). Results suggest that the e-cig examined had higher abuse liability than the IN but lower than combustible cigarettes. These data and methods may be useful for policymakers by revealing how e-cig abuse liability compares to tobacco/nicotine products with abuse liability profiles that are well established. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Nicotine absorption during electronic cigarette use among regular users

BACKGROUND

The capability of electronic cigarette devices (e-cigs) to deliver nicotine is key to their potential to replace combustible cigarettes. We compared nicotine delivery and subjective effects associated with the use of two classes of e-cigarettes and cigarettes.

METHODS

14 e-cigarette users were instructed to vape their own e-cigarette device every 20 seconds for 10 minutes while blood was drawn at 1, 2, 4, 6, 8, 10,12, and 15 minutes after initiating vaping. Users rated withdrawal symptoms and side effects before and after vaping. E-cigarette devices were classified as first-generation (same size as cigarette, no activation button) or advanced (larger than cigarette with an activation button). Separately, 10 cigarette smokers completed a similar protocol. Fisher's Exact Test and two-sided t-tests were used as appropriate to determine differences in outcomes between first-generation e-cigarette users, advanced e-cigarette users, and smokers.

RESULTS

Compared to first-generation devices, advanced devices were associated with greater serum nicotine Cmax (ng/ml) (11.5 v. 2.8, p = 0.0231) and greater nicotine boost (ng/ml) (10.8 v. 1.8, p = 0.0177). Overall, e-cigarettes users experienced a significant reduction in withdrawal and craving, although there were no significant differences between users of first-generation and advanced devices. Comparing e-cigarettes overall to cigarettes, cigarettes were associated with greater Cmax (25.9 v. 9.0, p = 0.0043) and greater nicotine boost (21.0 v. 8.2, p = 0.0128).

CONCLUSIONS

Advanced e-cigarettes delivered significantly more nicotine than first-generation devices but less than combustible cigarettes. Overall, e-cigarette use was associated with a reduction in withdrawal and craving with no reported side effects. The wide variation in nicotine absorption from different e-cigarette devices should be considered in studies of e-cigarettes for smoking cessation.

Prevalence of withdrawal symptoms from electronic cigarette cessation: A cross-sectional analysis of the US Population Assessment of Tobacco and Health

Electronic cigarette use can produce rapid and high levels of nicotine and thus could produce or maintain a physical dependence on nicotine. No experimental and limited observational studies have tested whether cessation of e-cigarettes is associated with withdrawal symptoms. To examine withdrawal from electronic cigarettes and compare it to that from tobacco cigarettes, we searched the US Population Assessment of Tobacco and Health Survey to locate successful and unsuccessful attempts to stop electronic or tobacco cigarettes. We examined electronic cigarette-only users, tobacco cigarette-only users and dual users. A minority of e-cigarette users who stopped/reduced e-cigarettes reported withdrawal symptoms but reported fewer symptoms than tobacco cigarette users who stopped/reduced tobacco cigarettes. E-cigarette withdrawal was not significantly greater in those who tried but were unable to stop e-cigarettes. In dual users, continued tobacco use appeared to reduce e-cigarette withdrawal but the opposite was not true. Given our small sample size and use of retrospective recall, an experimental test of e-cigarette abstinence is needed to better describe the severity of electronic cigarette withdrawal.

Fourth generation e-cigarette vaping induces transient lung inflammation and gas exchange disturbances: results from two randomized clinical trials

When heated by an electronic cigarette, propylene glycol and glycerol produce a nicotine-carrying-aerosol. This hygroscopic/hyperosmolar aerosol can deposit deep within the lung. Whether these deposits trigger local inflammation and disturb pulmonary gas exchanges is not known. The aim of this study was to assess the acute effects of high-wattage electronic cigarette vaping with or without nicotine on lung inflammation biomarkers, transcutaneous gas tensions, and pulmonary function tests in young and healthy tobacco smokers. Acute effects of vaping without nicotine on arterial blood gas tensions were also assessed in heavy smokers suspected of coronary artery disease. Using a single-blind within-subjects study design, 25 young tobacco smokers underwent three experimental sessions in random order: sham-vaping and vaping with and without nicotine at 60 W. Twenty heavy smokers were also exposed to sham-vaping (n = 10) or vaping without nicotine (n = 10) in an open-label, randomized parallel study. In the young tobacco smokers, compared with sham-vaping: 1) serum club cell protein-16 increased after vaping without nicotine (mean ± SE, −0.5 ± 0.2 vs. +1.1 ± 0.3 µg/l, P = 0.013) and vaping with nicotine (+1.2 ± 0.3 µg/l, P = 0.009); 2) transcutaneous oxygen tension decreased for 60 min after vaping without nicotine (nadir, −0.3 ± 1 vs. −15.3 ± 2.3 mmHg, P < 0.001) and for 80-min after vaping with nicotine (nadir, −19.6 ± 2.8 mmHg, P < 0.001). Compared with sham vaping, vaping without nicotine decreased arterial oxygen tension for 5 min in heavy-smoking patients (+5.4 ± 3.3 vs. −5.4 ± 1.9 mmHg, P = 0.012). Acute vaping of propylene glycol/glycerol aerosol at high wattage with or without nicotine induces airway epithelial injury and sustained decrement in transcutaneous oxygen tension in young tobacco smokers. Intense vaping conditions also transiently impair arterial oxygen tension in heavy smokers.

Emissions of Free Radicals, Carbonyls, and Nicotine from the NIDA Standardized Research Electronic Cigarette and Comparison to Similar Commercial Devices

E-cigarettes (e-cigs) are a diverse and continuously evolving group of products with four generations currently in the market. The National Institute on Drug Abuse (NIDA) standardized research e-cigarette (SREC) is intended to provide researchers with a consistent e-cig device with known characteristics. Thus, we conducted laboratory-based characterizations of oxidants and nicotine in aerosols produced from SREC and other closed-system, breath-activated, commercially available e-cigs (Blu and Vuse). We hypothesized that oxidant and nicotine production will be significantly affected in all devices by changes in puffing parameters. All e-cigs were machine vaped and the aerosols generated were examined for nicotine, carbonyls, and free-radicals while varying the puff-volumes and puff-durations to reflect typical human usage. The data were normalized on a per puff, per gram aerosol, and per milligram nicotine basis. We found that aerosol production generally increased with increasing puff-duration and puff-volume in all e-cigs tested. Increased puff-duration and puff-volume increased nicotine delivery for Blu and Vuse but not the SREC. We report, for the first time, reactive free-radicals in aerosols from all closed-system e-cigs tested, albeit at levels lower than cigarette smoke. Formaldehyde, acetaldehyde, acetone, and propionaldehyde were detected in the aerosols of all tested e-cigs. Carbonyl and free radical production is affected by puff-duration and puff volume. Overall, SREC was more efficient at aerosol and nicotine production than both Blu and Vuse. In terms of carbonyl and free radical levels, SREC delivered lower or similar levels to both other devices.

Nicotine pharmacokinetics of electronic cigarettes: A review of the literature

E-cigarettes are battery-powered electronic devices from which users can inhale nicotine following its aerosolisation from a liquid solution. Some regulators and public health bodies consider e-cigarettes as potentially playing a major role in tobacco harm reduction. Their ability to provide nicotine to smokers in both amount and in a manner and form generally similar to cigarette smoking have been proposed as key components to help smokers reduce or cease the use of combustible cigarettes. Nicotine pharmacokinetic studies of e-cigarettes have been performed for a number of years and are beginning to show how nicotine delivery is evolving as the products themselves evolve. In this review, we provide a critical overview of the literature to describe what is known about nicotine delivery from e-cigarettes. We will discuss how the progression of e-cigarette design, development, and user familiarity has allowed increases in nicotine availability to the user, in the context of how much and how rapidly nicotine is delivered during acute-use periods. This review will also provide insight into current research gaps and highlight the potential utility of modelling and the standardisation of methodologies used to assess nicotine delivery to facilitate identification of products that are best suited to displace cigarette smoking among adult smokers.

Assessment of the abuse liability of three menthol Vuse Solo electronic cigarettes relative to combustible cigarettes and nicotine gum

RATIONALE

We previously reported that following a short-term product use period, use of non-menthol Vuse Solo electronic cigarettes (ECs) resulted in product effect-related subjective responses and nicotine uptake between those of combustible cigarettes (high-abuse liability comparator) and nicotine gum (low-abuse liability comparator); the results were generally closer to those of nicotine gum.

OBJECTIVE

Using a similar design to the previous study, we evaluated the abuse liability of three menthol-flavored Vuse Solo ECs with the same nicotine contents (14, 29, and 36 mg) in a group of EC-naïve, menthol cigarette smokers, relative to comparator products.

METHODS

Six-hour nicotine uptake and ratings of subjective effects were used to determine abuse liability and pharmacokinetics.

RESULTS

Use of menthol Vuse Solo resulted in significantly lower responses to subjective measurements (product liking, intent to use product again, and liking of positive product effects), higher urge to smoke responses, and a lower peak (Cmax) and overall extent (AUC0-360) of nicotine uptake compared to smoking the usual brand menthol cigarette. When compared with use of nicotine gum, subjective responses to use of menthol Vuse ECs were in the same direction as those resulting from smoking cigarettes but were more similar to nicotine gum use in magnitude than they were to cigarettes.

CONCLUSION

These findings are concordant with our previous results and provide evidence that menthol Vuse Solo ECs have abuse liability that is lower than menthol cigarettes and potentially greater than that of nicotine gum.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02664012.