Changes in biomarkers of exposure and withdrawal symptom among Chinese adult smokers after completely or partially switching from combustible cigarettes to an electronic nicotine delivery system

This study assessed changes in biomarkers of exposure (BoE) after 5 days of completely or partially switching to an electronic nicotine delivery system (ENDS) use, compared with continued use of combustible cigarettes and smoking abstinence among Chinese adult smokers. A randomized, open-label, parallel-arm study was conducted among Chinese adult smokers who were naive ENDS users. Forty-six subjects were randomized to 4 study groups (n = 11-12 per group): exclusive ENDS use, dual use of ENDS and cigarettes, exclusive cigarettes use, and smoking abstinence. Subjects were confined in clinic for 5 consecutive days and product use was ad libitum. Nicotine and its metabolites (cotinine and 3-hydroxycotinine), and BoEs (AAMA, CEMA, HEMA, HMPMA, 3-HPMA, SPMA, exhaled CO, and exhaled NO) were measured. Withdrawal symptom was measured using MNWS throughout the 5-day period. Six urine BoEs of volatile organic compounds decreased by 55.1-84.1% in the exclusive ENDS use group, which is similar to the smoking abstinence group (67.2-87.4%). The level of decrease was 56.8-70.4% in the dual use group and 10.7-39.0% in the cigarettes group. Urine total nicotine exposure had a non-significant increase in the exclusive ENDS use group, and plasma nicotine and cotinine showed a trend of increasing day by day. After completely or partially switching to ENDS use among Chinese smokers, exposure to selected toxicants were significantly decreased. The results of this study add to the body of evidence that exposure to toxic substance decreased among smokers after complete or partial switch from combustible cigarettes to ENDS use. As part of transition to experienced ENDS use, this study found that smokers of the initial stage who have no prior ENDS experience may increase nicotine intake after switching to ENDS use.

Effect of menthol/mint-flavored pods on young JUUL E-cigarette users' subjective experience, puffing behavior, and nicotine exposure: A pilot study

BACKGROUND

Recent regulations have banned all flavors except menthol/mint and classic tobacco from pod-based e-cigarette devices such as JUUL. However, menthol/mint flavor can present a potential risk given its increasing popularity among young people in the US and its puffing and nicotine-enhancing properties. This study examines the impact of menthol/mint flavor manipulation on users' puffing behavior, subjective experience, and nicotine exposure among young people.

METHODS

JUUL users (n = 33, 18-24 years) attended two 60-min ad libitum e-cigarette use sessions (menthol/mint flavor vs. classic tobacco flavor) in a cross-over design. Puff topography and plasma nicotine concentration were measured, and participants completed subjective experience questionnaires.

RESULTS

Following the use of the menthol/mint-flavored pod, increases were observed in measures of satisfaction, pleasurable/interest to use, willingness to use again, enjoyment, urge to vape, product appeal, taste, and concentration (p < .05 for all). For example, compared to the classic tobacco flavor, participants experienced significantly more satisfaction of the product (4.24 vs. 3.09; p = .001) and sensation enjoyment of the product (3.55 vs. 2.48; p = .002) when using the menthol/mint flavor. While means of the plasma nicotine boost and puff parameters were lower in the classic tobacco condition compared to the menthol/mint flavor condition, no statistical significance was observed between the two conditions (p > .05 for all).

CONCLUSIONS

Results of this pilot study suggest that menthol/mint-flavor increases e-cigarette users' subjective experience significantly. Regulating menthol/mint flavor is a potentially promising strategy to curb e-cigarette use among young people.

Tobacco smoke exposure enhances reward sensitivity in male and female rats

RATIONALE

Systemic administration of the tobacco smoke constituent nicotine stimulates brain reward function in rats. However, it is unknown if the inhalation of tobacco smoke affects brain reward function.

OBJECTIVES

These experiments investigated if exposure to smoke from high-nicotine SPECTRUM research cigarettes increases reward function and affects the rewarding effects of nicotine in adult male and female Wistar rats.

METHODS

Reward function after smoke or nicotine exposure was investigated using the intracranial self-stimulation (ICSS) procedure. A decrease in reward thresholds reflects an increase in reward function. In the first experiment, the rats were exposed to tobacco smoke for 40 min/day for 9 days, and the rewarding effects of nicotine (0.03-0.6 mg/kg) were investigated 3 weeks later. In the second experiment, the dose effects of tobacco smoke exposure (40-min sessions, 1-4 cigarettes burnt simultaneously) on reward function were investigated.

RESULTS

Tobacco smoke exposure did not affect the nicotine-induced decrease in reward thresholds or response latencies in male and female rats. Smoke exposure lowered the brain reward thresholds to a similar degree in males and females and caused a greater decrease in latencies in females. There was a positive relationship between plasma nicotine and cotinine levels and the nicotine content of the SPECTRUM research cigarettes. Similar smoke exposure conditions led to higher plasma nicotine and cotinine levels in female than male rats.

CONCLUSION

These findings indicate that tobacco smoke exposure enhances brain reward function but does not potentiate the rewarding effects of nicotine in male and female rats.

Nicotine delivery and user reactions to Juul EU (20 mg/ml) compared with Juul US (59 mg/ml), cigarettes and other e-cigarette products

RATIONALE

The degree to which the EU version of Juul with 20 mg/ml nicotine (Juul EU) delivers nicotine to users is likely to determine its treatment potential.

OBJECTIVES

To compare the pharmacokinetic profile and user ratings of Juul EU, Juul US (59 mg/ml nicotine), cigarettes and other e-cigarette (EC) products.

METHODS

In a within-subjects crossover design, 18 vapers used, at separate sessions, their own brand cigarette (OBC), Juul US and Juul EU for 5 min ad libitum, after overnight abstinence. Seven of the participants also tested eight other EC previously. Blood samples were taken at baseline and 2, 4, 6, 8, 10 and 30 min after initiating product use. Products were rated on a range of characteristics.

RESULTS

Juul EU delivered less nicotine than OBC (t(13) = -4.64 p < .001) and than Juul US (t(13) = -6.40, p < .001): AUC0 ≥ 30 77.3, 324.8 and 355.9, respectively. Maximum nicotine concentration (Cmax) was also much lower for Juul EU than Juul US (z = -3.59, p < .001): Cmax 3.8 ng/ml vs 21.1 ng/ml, respectively. Juul EU was perceived to relieve urges to smoke less than Juul US (z = -2.29, p = .022) and to provide less nicotine (z = -2.57. p = 0.010). Juul EU delivered less nicotine than refillable EC (Cmax: t(6) = 3.02, p = 0.023; AUC0 ≥ 30: z = -2.20, p = 0.028) and also less than cig-a-like EC, though the difference did not reach significance (Cmax: t(6) = 2.49, p = 0.047; AUC0 ≥ 30: z = -1.99, p = 0.046). Subjective ratings of Juul EU and other EC products were similar.

CONCLUSIONS

Juul EU delivers much less nicotine to users than Juul US, and also less than refillable EC products. It may thus have more limited potential to help smokers quit.

Maternal waterpipe tobacco smoke exposure during lactation induces hormonal and biochemical changes in rat dams and offspring

Waterpipe smoking is common among pregnant and breastfeeding women. Herein, the effects of waterpipe tobacco smoke (WTS) exposure during lactation on milk composition, hormonal levels and biochemical profile in dams and pups were investigated. Lactating Wistar rats were randomly assigned to receive either WTS (2 hours per day) or fresh air (control group). Milk was collected on day 21 and analysed for protein, lactose and total fat. Blood, from dams and pups, was analysed for insulin, glucose, lipid profile, leptin, prolactin and corticosterone. WTS exposure during lactation increased the blood level of HDL and corticosterone in dams (P < .05). However, the level of milk lactose and blood glucose was reduced in dams after the exposure to WTS during lactation (P < .05). WTS during lactation significantly increased levels of triglycerides, LDL and leptin (P < .05), and a trend of increase in blood level of nicotine and prolactin in pups. Levels of other parameters were not affected by WTS exposure in dams and pups. In conclusion, WTS exposure during lactation altered the milk composition and altered lipid profile, glucose homeostasis and hormonal levels in dams and pups. It is necessary to adopt strategies to enhance tobacco cessation during breastfeeding.

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.

A randomised controlled single-centre open-label pharmacokinetic study to examine various approaches of nicotine delivery using electronic cigarettes

Smokers who switch completely to e-cigarettes may reduce their relative risk of tobacco-related disease. Effective nicotine delivery from e-cigarettes is important in consumer acceptance. We assessed whether protonated nicotine and e-cigarette devices delivering greater aerosol mass increase nicotine delivery and product liking. A randomised controlled non-blinded eight-arm crossover study was used to assess plasma nicotine pharmacokinetics and product liking for two e-cigarettes (Vype ePen3 and Vype ePen) with various nicotine e-liquid formulations and a conventional cigarette among 24 healthy dual-users of cigarettes and e-cigarettes. Product use and puff count were also assessed. Results show that nicotine bioavailability was greater for Vype ePen3 with greater aerosol mass delivery than for Vype ePen (Cmax, p = 0.0073; AUC0-120 min, p = 0.0102). Protonated nicotine (18 mg/mL, medium protonation) e-liquid yielded higher nicotine bioavailability than unprotonated nicotine (18 mg/mL) e-liquid (Cmax, p = 0.0001; AUC0-120 min, p = 0.0026). There was no significant difference in Tmax between e-liquids. Nicotine bioavailability did not differ between nicotine benzoate formulation (30 mg/mL nicotine, high protonation) and combustible cigarettes (Cmax, p = 0.79; AUC0-120 min, p = 0.13). Vype ePen3 with protonated nicotine delivers nicotine more efficiently with the potential to increase product liking relative to earlier devices using unprotonated e-liquid.

Electronic cigarettes cause alteration in cardiac structure and function in diet-induced obese mice

In spite of the widespread use of electronic cigarettes, also known as e-cigarettes, and the proposed adverse cardiac effects of nicotine, the detrimental effects of e-cigarettes on the heart are not well known. This study examines the detrimental effects of e-cigarettes with nicotine at doses that yield circulating nicotine and cotinine in the ranges similar to the levels found in habitual smokers, and a high fat diet (HFD) on cardiac structure and function in a commonly used model of diet-induced obesity (DIO). C57BL/6J mice on an HFD were exposed to e-cigarette in the presence (2.4% nicotine) or absence (0% nicotine) of nicotine and saline aerosol for 12 weeks. Echocardiographic data demonstrated a decrease in left ventricular (LV) fractional shortening, LV ejection fraction, and velocity of circumferential fiber shortening (VCF) in mice treated with e-cigarette (2.4% nicotine) compared to e-cigarette (0% nicotine) or saline exposed mice. Cardiomyocytes (CMs) of mice treated with e-cigarette (2.4% nicotine) exhibited LV abnormalities, including lipid accumulation (ventricular steatosis), myofibrillar derangement and destruction, and mitochondrial hypertrophy, as revealed by transmission electron microscopy. The detrimental effects of e-cigarettes (2.4% nicotine) on cardiac structure and function was accompanied by increased oxidative stress, plasma free fatty acid levels, CM apoptosis, and inactivation of AMP-activated protein kinase and activation of its downstream target, acetyl-CoA-carboxylase. Our results indicate profound adverse effects of e-cigarettes (2.4% nicotine) on the heart in obese mice and raise questions about the safety of the nicotine e-cigarettes use.

Adolescent nicotine and tobacco smoke exposure enhances nicotine self-administration in female rats

Most people start experimenting with tobacco products or e-cigarettes in early adolescence and become habitual smokers in late adolescence or adulthood. These studies investigated if exposure to tobacco smoke or nicotine during early and mid-adolescence affects nicotine intake in late adolescence and early adulthood. Male and female rats were exposed to tobacco smoke from low- and high-nicotine SPECTRUM cigarettes or nicotine (0.3 mg/kg, twice a day) from postnatal day (P) 24-42. The self-administration sessions started at P55. The rats self-administered nicotine for 14-15 days under a fixed-ratio 1 schedule, and on the first day, the maximum number of infusions was twenty. Exposure to smoke from high, but not low, nicotine cigarettes during adolescence increased nicotine self-administration in female but not male rats. Adolescent treatment with nicotine facilitated nicotine self-administration. On the first day of nicotine self-administration, nicotine-treated rats reached the maximum number of infusions before the saline-treated control rats. Nicotine intake was also higher in the nicotine-treated female rats than in the saline-treated females. There was no sex difference in nicotine intake in controls when the data from the studies were combined. Smoke exposure led to a dose-dependent increase in plasma nicotine and cotinine levels in adolescent rats. Exposure to smoke from high-nicotine cigarettes and 0.3 mg/kg of nicotine led to plasma nicotine and cotinine levels that are similar to those in tobacco users. These findings indicate that in females, but not males, exposure to nicotine during adolescence may facilitate smoking and e-cigarette use later in life.

Nicotine delivery and users' reactions to Juul compared with cigarettes and other e-cigarette products

AIMS

To assess the pharmacokinetic (PK) profile of, and users' reactions to, Juul (59 mg nicotine/ml) as an indication of its therapeutic and dependence potential.

DESIGN

Cross-over, within-subjects study in which participants attended after overnight abstinence on separate sessions and smoked a cigarette or used Juul or eight other types of e-cigarettes (EC) ad libitum for 5 minutes. The Juul product used was the version available in the United States that has more nicotine in the e-liquid than the one available in the European Union.

SETTING

Laboratory setting in the United Kingdom.

PARTICIPANTS

Twenty dual users (smokers who also vape) provided data on Juul and cigarettes, with eight also providing data on other EC products.

MEASUREMENTS

At each session, number of puffs taken was counted during the 5-minute product use period and blood samples were taken at baseline and at 2, 4, 6, 8, 10 and 30 minutes after starting smoking/vaping and analysed for nicotine. Participants also monitored their urges to smoke and rated the products on a range of characteristics.

FINDINGS

Juul's PK profile was close to the PK profile of cigarettes [maximum concentration (Cmax ) = 20.4 versus 19.2 ng/ml; time to maximum concentration (Tmax ) = 4 versus 6 minutes; area under the curve (AUC): 307.9 versus 312.6, respectively]. Compared with other EC products, Juul had shorter Tmax [4 minutes, (IQR = 2.5-4.0) versus 6.3 minutes, (IQR = 4.7 - 8.1), P = 0.012] and higher Cmax (28.9 (SD = 15.6) versus 10.6 (SD = 5.5), P = 0.013) despite a lower number of puffs (12.5 (SD = 4.2) versus 17.0 (SD = 4.2), P = 0.084). Compared with other e-cigarette products, it also provided faster reduction of urges to smoke and obtained more favourable subjective ratings.

CONCLUSION

Juul's PK profile and user ratings suggest that it could be more effective than other EC products in helping smokers to quit smoking, but it may also have a higher potential to generate regular use in non-smokers.

A Procedure to Standardize Puff Topography During Evaluations of Acute Tobacco or Electronic Cigarette Exposure

INTRODUCTION

Documenting factors that influence differential sensitivity to acutely inhaled nicotine products requires carefully controlling the amount of exposure (dose), and thus a procedure by which to control such exposure.

METHODS

We evaluated consistency of puff volume from intermittent acute exposures to smoked tobacco cigarettes (study 1, n = 45, plus a comparison study of uninstructed use with n = 59) and to vaped electronic cigarettes (e-cigarettes; study 2, n = 27 naive to e-cigarettes) in adult-dependent smokers. All in primary studies 1 and 2 participated in research administering different nicotine levels in each product under blind conditions, one per session using within-subject designs. In both studies, participants followed an automated instructional procedure on a computer monitor standardizing the timing and amount of exposure to each product during a given trial, with four trials per session, each separated by 20 minutes. Puff volume per trial via Clinical Research Support System (CReSS) was the primary dependent measure to determine consistency across trials via intraclass correlation coefficients (ICCs).

RESULTS

Control over topography with both inhaled products was demonstrated by highly significant ICCs for puff volume across trials. Instructed control with own brand was generally better in study 1 than with uninstructed smoking in the comparison sample, as expected. As intended, reliability of puff volume generally did not differ by menthol preference or sex in either study, but ICCs in study 2 tended to be lower for some men using the placebo e-cigarette.

CONCLUSIONS

This instructional procedure may substantially improve control over amounts of acute exposure to tobacco or e-cigarette use.

IMPLICATIONS

Control over topography in studies of acute exposure to these inhaled products can potentially aid validity of research into differential sensitivity to use, so findings can be attributed to factors of interest and not to variable exposure. Our procedure minimized variability in exposure to the same product and between moderate nicotine products, but remaining differences suggest that compensation for very low or no nicotine commercial products may be difficult to totally eliminate with these instructions alone. Further study is needed to determine this procedure's utility with other inhaled products among experienced users and when comparing different products in between-groups analyses.

Evidence of compensation among waterpipe smokers using harm reduction components

OBJECTIVES

We examined two waterpipe tobacco smoking components advertised to reduce harm to determine if they result in lower levels of biomarkers of acute exposure.

METHODS

We conducted a crossover study of 34 experienced waterpipe smokers smoking a research-grade waterpipe in three configurations ad libitum in a controlled chamber: control (quick-light charcoal), electric (electric heating) and bubble diffuser (quick-light charcoal and bubble diffuser). We collected data on smoking topography, environmental carbon monoxide (CO), subjective effects, heart rate, plasma nicotine and exhaled CO and benzene.

RESULTS

Smokers' mean plasma nicotine, heart rate, and exhaled benzene and CO boost were all significantly lower for electric compared with control. However, smokers puffed more intensely and took significantly more and larger volume puffs for a larger total puffing volume (2.0 times larger, p<0.0001) when smoking electric; machine yields indicate this was likely due to lower mainstream nicotine. Smokers rated electric smoking experience less satisfying and less pleasant. For charcoal heating, the mean mass of CO emitted into the chamber was ~1 g when participants smoked for a mean of 32 minutes at a typical residential ventilation rate (2.3 hr-1).

CONCLUSION

Waterpipe smokers engaged in compensation (i.e., increased and more intense puffing) to make up for decreased mainstream nicotine delivery from the same tobacco heated two ways. Waterpipe components can affect human puffing behaviours, exposures and subjective effects. Evidence reported here supports regulation of waterpipe components, smoking bans in multifamily housing and the use of human studies to evaluate modified or reduced risk claims.

Relationship between skin melanin index and nicotine pharmacokinetics in African American smokers

BACKGROUND

Blacks bear a disproportionate burden of smoking-related diseases and experience greater difficulty quitting smoking than Whites. Nicotine has a high affinity for melanin, and it has been hypothesized that melanin levels might influence nicotine pharmacokinetics and enhance dependence. The aim of this study was to evaluate the hypothesis that melanin affects nicotine disposition kinetics in humans.

METHODS

Forty-four Black participants were administered intravenous infusions of deuterium-labeled nicotine and cotinine. Plasma concentrations of nicotine and cotinine were measured, and pharmacokinetic parameters were estimated. The constitutive and facultative melanin indexes were measured using a dermaspectrophotometer.

RESULTS

The median constitutive melanin index was 60.7 (32.8-134.7) and the median facultative melanin index 68.1 (38.6-127.1). The mean (±SD) nicotine elimination half-life was 136 min (±33.5), clearance was 1237 mL/min (±331), and Vss was 204 L (±66), or 2.6 L/kg (±0.7). No evidence of significant differences was found in nicotine pharmacokinetic parameters by comparing participants in different melanin index quartiles (outliers with very high melanin index had similar pharmacokinetic values to others). Differences were not statistically significant when adjusted for age, BMI, sex and CYP2A6 genotype or the nicotine metabolite ratio (NMR), and no evidence of significant correlations were found between melanin (facultative or constitutive) and the pharmacokinetic parameters of nicotine or cotinine or tobacco dependence measures.

CONCLUSIONS

Based on our finding in this group of Black smokers, we could not confirm the hypothesis that melanin significantly affects nicotine disposition kinetics or measures of tobacco dependence.

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).

Evaluating the effects of switching from cigarette smoking to using a heated tobacco product on health effect indicators in healthy subjects: study protocol for a randomized controlled trial

Tobacco heating products (THPs) are a potentially safer alternative to combustible cigarette smoking. Through continued use, THPs may reduce smoking-related disease risk, whilst maintaining the sensorial experience and nicotine delivery sought by smokers. While literature evidence of the biological effects of THP aerosol exposure is increasing, there remains a knowledge gap with respect to substantiation of THP reduced risk potential in longer term real-life use. This randomized, multi-centre, controlled clinical study will test the hypotheses that following a switch from combustible cigarettes to a THP for 1 year, participants will experience a sustained reduction in exposure to tobacco-related toxicants that will lead to favourable changes in health effect indicators associated with smoking-related disease development. Changes in such indicators will be contextualized against smoking cessation and never-smoker cohorts. Up to 280 participants who do not intend to quit smoking will be randomized to continued combustible smoking (arm A, up to n = 80) or a commercially available THP (arm B n = 200). Furthermore, up to 190 participants with a high intent to quit smoking will undergo smoking cessation (arm D), and 40 never smokers will serve as a control group (arm E). Recruitment numbers were determined to be sufficient to achieve n = 50 in arms A, B and D, at study end. Enrolment started in March 2018 and the trial is scheduled to be completed in March 2020. Data from this study will be a valuable addition to the growing body of evidence in the field of understanding the individual and public health impact of THPs.Clinical Trial Registration: https://www.isrctn.com/ISRCTN81075760.

A randomised, open-label, cross-over clinical study to evaluate the pharmacokinetic profiles of cigarettes and e-cigarettes with nicotine salt formulations in US adult smokers

E-cigarettes containing 'nicotine salts' aim to increase smoker's satisfaction by improving blood nicotine delivery and other sensory properties. Here, we evaluated the pharmacokinetic profiles and subjective effects of nicotine from two e-cigarette device platforms with varying concentrations of nicotine lactate (nicotine salt) e-liquid relative to conventional cigarettes. A randomised, open-label, cross-over clinical study was conducted in 15 healthy US adult smokers. Five different e-cigarette products were evaluated consecutively on different days after use of own brand conventional cigarette. Plasma nicotine pharmacokinetics, subjective effects, and tolerability were assessed following controlled use of the products. The rate of nicotine absorption into the bloodstream was comparable from all e-cigarettes tested and was as rapid as that for conventional cigarette. However, in all cases, nicotine delivery did not exceed that of the conventional cigarette. The pharmacokinetic profiles of nicotine salt emissions were also dependent upon the properties of the e-cigarette device. Subjective scores were numerically highest after smoking a conventional cigarette followed by the myblu 40-mg nicotine salt formulation. The rise in nicotine blood levels following use of all the tested e-cigarettes was quantified as 'a little' to 'modestly' satisfying at relieving the desire to smoke. All products were well tolerated with no notable adverse events reported. These results demonstrate that, while delivering less nicotine than a conventional cigarette, the use of nicotine salts in e-cigarettes enables cigarette-like pulmonary delivery of nicotine that reduces desire to smoke.

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.

Tobacco Smoking and Brain Endogenous Opioid Release: More Than Nicotine Alone

INTRODUCTION

The effects of smoking denicotinized (denic) and average nicotine (avnic) tobacco cigarettes were studied on brain mu opioid receptor binding by positron emission tomography with 11C carfentanil. The results indicated the importance of physiological and psychological effects induced by denic smoking.

METHODS

Regional mu opioid binding potential (nondisplaceable binding potential, BPND) was measured in 20 adult male overnight abstinent chronic tobacco smokers. The denic sessions were conducted about 8:00 am followed by avnic sessions about 2 hours later. Venous plasma nicotine levels and scores of craving to smoke were assessed before and after each smoking session. Fagerstrom scores of nicotine dependence were determined. Pearson's and Spearman's correlation tests were used to examine associations between BPND and other smoking parameters.

RESULTS

Surprisingly, the very low plasma nicotine peak levels after denic smoking (mean ± SD: 3.3 ± 1.8 ng/mL) were significantly correlated with BPND after denic and avnic smoking. Equally surprising no association was found between nicotine levels after avnic smoking and BPND. Delta craving scores and Fagerstrom scores were correlated with both BPND after denic and avnic in several brain regions.

CONCLUSIONS

Very small amounts of nicotine, psychological and behavioral effects of denic smoking appear to have important actions on the endogenous mu opioid system.

IMPLICATIONS

Associations between very low venous plasma nicotine levels after denic smoking and regional brain mu opioid receptor availability are a surprising "placebo" effect. Delta craving and Fagerstrom scores were correlated with BPND in several brain regions including amygdala, hippocampus, insula, nucleus accumbens, putamen, and ventral striatum. This study is limited by modest Power (mean 1 - β = 0.6) for all correlation analyses.

Vascular endothelial function is impaired by aerosol from a single IQOS HeatStick to the same extent as by cigarette smoke

BACKGROUND

Heated tobacco products (also called 'heat-not-burn' products) heat tobacco at temperatures below that of combustion, causing nicotine and other compounds to aerosolise. One such product, IQOS from Philip Morris International, is being marketed internationally with claims of harm reduction. We sought to determine whether exposure to IQOS aerosol impairs arterial flow-mediated dilation (FMD), a measure of vascular endothelial function that is impaired by tobacco smoke.

METHODS

We exposed anaesthetised rats (n=8/group) via nose cone to IQOS aerosol from single HeatSticks, mainstream smoke from single Marlboro Red cigarettes or clean air for a series of consecutive 30 s cycles over 1.5-5 min. Each cycle consisted of 15 or 5 s of exposure followed by removal from the nose cone. We measured pre-exposure and postexposure FMD, and postexposure serum nicotine and cotinine.

RESULTS

FMD was impaired comparably by ten 15 s exposures and ten 5 s exposures to IQOS aerosol and to cigarette smoke, but not by clean air. Serum nicotine levels were similar to plasma levels after humans have smoked one cigarette, confirming that exposure conditions had real-world relevance. Postexposure nicotine levels were ~4.5-fold higher in rats exposed to IQOS than to cigarettes, despite nicotine being measured in the IQOS aerosol at ~63% the amount measured in smoke. When IQOS exposure was briefer, leading to comparable serum nicotine levels to the cigarette group, FMD was still comparably impaired.

CONCLUSIONS

Acute exposures to IQOS aerosol impairs FMD in rats. IQOS use does not necessarily avoid the adverse cardiovascular effects of smoking cigarettes.

Evaluation of the impact of waterpipe tobacco smoke exposure on the activity and expression of rat hepatic CYP450: a pharmacokinetic study

Waterpipe smoke contains many toxic constituents that can alter drug pharmacokinetics. This study assessed the effect of waterpipe smoke exposure on the activity and expression of CYP450 enzymes in rats. Animals (n = 10/group) were exposed to either waterpipe smoke or side-stream cigarette smoke for 1 h/day (6 days/week) for 31 days, or fresh air (control). An intragastric cocktail solution containing three probe drugs, phenacetin, chlorzoxazone and testosterone was administered to assess the activity of CYP1A2, CYP2E1 and CYP3A, respectively. Serum concentrations were determined using LC-MS/MS and the pharmacokinetic parameters were calculated. The mRNA expression of hepatic enzymes was also quantified. Waterpipe and cigarette smoke exposure did not significantly alter the pharmacokinetics of phenacetin, chlorzoxazone and testosterone. For example, the clearance and drug exposure values were comparable among groups for all probe drugs. Additionally, there was no significant effect of waterpipe and cigarette smoke on mRNA expression of hepatic CYP1A2, CYP2E1 and CYP3A2. The results demonstrate that waterpipe smoke exposure had no effect on the functional expression of three key CYP450 isoforms in rats. Future research is required with longer exposure periods to waterpipe smoke. Such work serves to enhance current understanding of effect of waterpipe smoke exposure on pharmacokinetics.

An enzymatic approach reverses nicotine dependence, decreases compulsive-like intake, and prevents relapse

Tobacco use disorder is the leading cause of disease and preventable death worldwide, but current medications that are based on pharmacodynamics have low efficacy. Novel pharmacokinetic approaches to prevent nicotine from reaching the brain have been tested using vaccines, but these efforts have failed because antibody affinity and concentration are not sufficient to completely prevent nicotine from reaching the brain. We provide preclinical evidence of the efficacy of an enzymatic approach to reverse nicotine dependence, reduce compulsive-like nicotine intake, and prevent relapse in rats with a history of nicotine dependence. Chronic administration of NicA2-J1, an engineered nicotine-degrading enzyme that was originally isolated from Pseudomonas putida S16, completely prevented nicotine from reaching the brain and reversed somatic signs of withdrawal, hyperalgesia, and irritability-like behavior in nicotine-dependent rats with a history of escalation of nicotine self-administration. NicA2-J1 also decreased compulsive-like nicotine intake, reflected by responding despite the adverse consequences of contingent footshocks, and prevented nicotine- and stress (yohimbine)-induced relapse. These results demonstrate the efficacy of enzymatic therapy in treating nicotine addiction in advanced animal models and provide a strong foundation for the development of biological therapies for smoking cessation in humans.

Differences in puff topography, toxicant exposure, and subjective response between waterpipe tobacco smoking men and women

Waterpipe tobacco smoking (WTS) exposes users to toxicants in much greater amounts than a cigarette. Little is known about how gender affects WTS toxicant exposure and subjective response. Data from three WTS clinical laboratory studies were combined for analysis. Participants (N = 99; 38 women) completed a 45-min WTS session where they smoked a waterpipe ad libitum. Puff topography was measured throughout, and plasma nicotine concentration, expired air carbon monoxide (CO), and subjective responses were measured pre- and post-WTS. There was a gender effect for total puff volume with men inhaling a greater smoke volume, on average (M = 59.9 L, SD = 40.7), compared with women (M = 38.8 L, SD = 27.8; p < .01). Men had greater post-WTS mean plasma nicotine concentrations (M = 10.0 ng/ml, SD = 7.1) compared with women (M = 6.9 ng/ml, SD = 5.2; p < .05). Post-WTS expired air CO was not associated with gender (men M = 27.6 ppm, SD = 18.9; women M = 22.7 ppm, SD = 17.0, ns). Relative to men, women had higher post-WTS scores for subjective measures of "nauseous," "dizzy," "nervous," "headache," and "heart pounding." Men and women are exposed to toxicants during WTS, and men may achieve higher nicotine exposure than women, likely resulting from differences in smoke inhaled. However, similar post-WTS expired air CO between men and women and higher ratings of negative subjective responses among women may indicate that factors beyond puff topography may impact toxicant exposure and subjective response to WTS. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Acute Effect of Hookah Smoking on Arterial Stiffness and Wave Reflections in Adults Aged 18 to 34 Years of Age

Hookah (waterpipe) smoking is rapidly increasing in popularity worldwide. Despite being heavily advertised in the media as a healthier alternative to cigarettes, the toxicology of hookah smoke suggest otherwise. Cigarette smoking unequivocally causes an acute increase in arterial stiffness, but whether hookah does the same is unknown. In 48 young healthy habitual hookah but not cigarette smokers, we measured heart rate, peripheral and central blood pressure, carotid-femoral pulse wave velocity (measure of arterial stiffness), aortic augmentation index (measure of wave reflection), plasma nicotine, and exhaled carbon monoxide before and after ad lib hookah smoking. Hookah smoking increased heart rate by +16 ± 1 beats/min and mean brachial arterial pressure by +6 ± 1 mm Hg (both p <0.05, mean ± SE). Most importantly, it increased carotid-femoral pulse wave velocity and aortic augmentation index by +0.66 ± 0.09 m/s^-1 and +8.76 ± 3.99%, respectively (p <0.05, mean ± SE), denoting increased acute arterial stiffness. These vascular effects were accompanied by increases in plasma nicotine concentration (+5.8 ± 1.2 ng/ml, p <0.05) and expired carbon monoxide (+25.44 ± 1.68 ppm, p <0.05). All these parameters were unchanged during time-control studies (n = 14). Thus, in contrast to effective media marketing of hookah as a safer alternative to cigarettes, the present study shows for the first time that in young adult hookah smokers, a single hookah smoking session causes an acute increase in arterial stiffness of comparable magnitude to what has been previously reported for cigarettes. Further research is warranted to determine whether habitual hookah smoking accelerates the age-dependent development of hypertension and its cardiovascular complications.

The nicotine-degrading enzyme NicA2 reduces nicotine levels in blood, nicotine distribution to brain, and nicotine discrimination and reinforcement in rats

BACKGROUND

The bacterial nicotine-degrading enzyme NicA2 isolated from P. putida was studied to assess its potential use in the treatment of tobacco dependence.

RESULTS

Rats were pretreated with varying i.v. doses of NicA2, followed by i.v. administration of nicotine at 0.03 mg/kg. NicA2 had a rapid onset of action reducing blood and brain nicotine concentrations in a dose-related manner, with a rapid onset of action. A 5 mg/kg NicA2 dose reduced the nicotine concentration in blood by > 90% at 1 min after the nicotine dose, compared to controls. Brain nicotine concentrations were reduced by 55% at 1 min and 92% at 5 min post nicotine dose. To evaluate enzyme effects at a nicotine dosing rate equivalent to heavy smoking, rats pretreated with NicA2 at 10 mg/kg were administered 5 doses of nicotine 0.03 mg/kg i.v. over 40 min. Nicotine levels in blood were below the assay detection limit 3 min after either the first or fifth nicotine dose, and nicotine levels in brain were reduced by 82 and 84%, respectively, compared to controls. A 20 mg/kg NicA2 dose attenuated nicotine discrimination and produced extinction of nicotine self-administration (NSA) in most rats, or a compensatory increase in other rats, when administered prior to each daily NSA session. In rats showing compensation, increasing the NicA2 dose to 70 mg/kg resulted in extinction of NSA. An enzyme construct with a longer duration of action, via fusion with an albumin-binding domain, similarly reduced NSA in a 23 h nicotine access model at a dose of 70 mg/kg.

CONCLUSIONS

These data extend knowledge of NicA2's effects on nicotine distribution to brain and its ability to attenuate addiction-relevant behaviors in rats and support its further investigation as a treatment for tobacco use disorder.

Prevalence of xenobiotic substances in first-trimester blood samples from Danish pregnant women: a cross-sectional study

OBJECTIVE

The aim of this study was to investigate the prevalence of xenobiotic substances, such as caffeine, nicotine and illicit drugs (eg, cannabis and cocaine), in blood samples from first-trimester Danish pregnant women unaware of the screening.

DESIGN

A cross-sectional study examined 436 anonymised residual blood samples obtained during 2014 as part of the nationwide prenatal first-trimester screening programme. The samples were analysed by ultra performance liquid chromatography with high-resolution time-of-flight mass spectrometry.

SETTING

An antenatal clinic in a Danish city with 62 000 inhabitants, where >95% of pregnant women joined the screening programme.

PRIMARY AND SECONDARY OUTCOME MEASURES

The prevalence and patterns of caffeine, nicotine, medication and illicit drug intake during the first trimester of pregnancy.

RESULTS

The prevalence of prescription and over-the-counter drug detection was 17.9%, including acetaminophen (8.9%) and antidepressants (3.0%), of which citalopram (0.9%) was the most frequent. The prevalence of illegal drugs, indicators of smoking (nicotine/cotinine) and caffeine was 0.9%, 9.9%, and 76.4%, respectively. Only 17.4% of women had no substance identified in their sample.

CONCLUSIONS

This study emphasises the need for further translational studies investigating lifestyle habits during pregnancy, as well as the underlying molecular mechanisms through which xenobiotic substances may affect placental function and fetal development.

Large Cigars: Smoking Topography and Toxicant Exposure

Background

Cigar smoking in the United States continues despite decreases in cigarette smoking and increased tobacco control efforts. We compared large cigar and cigarette smoking for use patterns, smoking topography, and toxicant exposure.

Methods

Dual users (n = 17, 94% men, 77% African American) smoked ad libitum either their usual cigarette brand or a study large cigar (Phillies Blunt) in two laboratory sessions. Plasma nicotine and exhaled carbon monoxide were collected before and after smoking. Smoking topography measures of puff volume, puff duration, puff velocity, and interpuff interval were also collected.

Results

Both cigarettes and large cigars significantly increased plasma nicotine and carbon monoxide and significantly decreased the urge to smoke. Cigarettes delivered more nicotine per gram of tobacco smoked and per 1000 mL of puff volume. Number of puffs, time to smoke, puff volume, and puff velocity were significantly larger and interpuff interval was significantly shorter in large cigar smoking. The temporal pattern of puffing more intensely at the beginning of smoking was similar for both large cigars and cigarettes.

Conclusions

People who regularly use both large cigars and cigarettes adapt their smoking pattern such that they are exposed to similar levels of nicotine from each product. The immediate increase in plasma nicotine and carbon monoxide suggest significant inhalation of large cigar smoke. These data call to question the assumption that cigar smoking is less toxic than cigarette smoking. By smoking large cigars, dual users expose themselves to toxic components that have been linked with the addiction risk, morbidity, and mortality of cigarette smoking.

Implications

This study found that dual users of large cigars and cigarettes inhale significant quantities of carbon monoxide, nicotine, and presumably other components of mainstream smoke. Large cigar smoke exposure may lead to or sustain nicotine addiction as wells as subject large cigar consumers to similar risks associated with cigarette smoking such as lung cancer and cardiovascular disease.

Nicotine delivery efficiency of first- and second-generation e-cigarettes and its impact on relief of craving during the acute phase of use

Knowledge about the change in blood nicotine concentrations during the first five minutes (acute phase) of e-cigarette vaping is important to determine whether the used product has a dependence potential or may be an efficient nicotine replacement product. To address this issue, we monitored blood nicotine levels during the acute phase in volunteers using disposable cigalikes (CLs) and a tank model (TM) and compared them with blood nicotine levels in subjects using a tobacco cigarette (TC). In parallel, heart rate changes were continually measured and withdrawal symptoms and craving were assessed with the Questionnaire on Smoking Urges before and immediately after the vaping/smoking sessions. Additionally, at the end of each session negative health effects were rated on a visual analog scale. After five minutes of e-cigarette or TC use, the mean nicotine plasma concentrations were as follows: CLs, 5.5ng/ml; TM, 9.3ng/ml; TC, 17.1ng/ml. Nicotine levels increased significantly faster in the first 4min of consuming a TC than with the CLs and the TM. The highest rate of increase in nicotine concentration was found with the TC (6.8ng/ml) and TM (2.3ng/ml) between the 1st and 2nd minute, whereas the CLs showed comparatively small changes in the amount delivered over the five minutes. Withdrawal and craving for smoking decreased with the TM by the same amount as with the TC, even though less nicotine was delivered to the blood and considerably fewer side effects occurred. The heart rate of TM users was also markedly lower than that of the TC users. Unlike CLs, TM e-cigarettes represent an effective source of nicotine and might be used as an alternative nicotine replacement product to aid smoking cessation. However, nicotine plasma levels observed in TM users after short-time vaping have also the potential to produce and sustain nicotine addiction.

Nicotine pharmacokinetic profiles of the Tobacco Heating System 2.2, cigarettes and nicotine gum in Japanese smokers

Two open-label randomized cross-over studies in Japanese smokers investigated the single-use nicotine pharmacokinetic profile of the Tobacco Heating System (THS) 2.2, cigarettes (CC) and nicotine replacement therapy (Gum). In each study, one on the regular and one on the menthol variants of the THS and CC, both using Gum as reference, 62 subjects were randomized to four sequences: Sequence 1: THS - CC (n = 22); Sequence 2: CC - THS (n = 22); Sequence 3: THS - Gum (n = 9); Sequence 4: Gum - THS (n = 9). Plasma nicotine concentrations were measured in 16 blood samples collected over 24 h after single use. Maximal nicotine concentration (Cmax) and area under the curve from start of product use to time of last quantifiable concentration (AUC0-last) were similar between THS and CC in both studies, with ratios varying from 88 to 104% for Cmax and from 96 to 98% for AUC0-last. Urge-to-smoke total scores were comparable between THS and CC. The THS nicotine pharmacokinetic profile was close to CC, with similar levels of urge-to-smoke. This suggests that THS can satisfy smokers and be a viable alternative to cigarettes for adult smokers who want to continue using tobacco.

Protective effects of quercetin and vitamin C against nicotine-induced toxicity in the blood of Wistar rats

Nicotine is a potential inducer of oxidative stress, through which it can damage numerous biological molecules. The aim of our study was to investigate the prooxidative effects of nicotine and protective (additive or synergistic) effects of quercetin and vitamin C in the blood of experimental animals, to determine whether the combination of these antioxidants might be beneficial for clinical purposes. Wistar albino rats were receiving intraperitoneal nicotine injection (0.75 mg kg-1 per day) or saline (control group) or nicotine plus quercetin (40 mg kg-1 per day) and vitamin C (100 mg kg-1 per day) for three consecutive days. On day 4, we determined their blood lipid profile, liver enzymes, oxidative stress parameters, and antioxidative system parameters. Compared to untreated control, nicotine significantly increased total cholesterol, LDLcholesterol, triglycerides, liver enzymes (alanine transaminase, aspartate transaminase, and lactate dehydrogenase) and oxidative stress parameters (superoxide anion, hydrogen peroxide, and lipid peroxide) and decreased HDL-cholesterol, glutathione, and superoxide dismutase/catalase activity. Quercetin + vitamin C reversed these values significantly compared to the nicotine alone group. Our results confirm that nicotine has significant prooxidative effects that may disrupt the redox balance and show that the quercetin + vitamin C combination supports antioxidant defence mechanisms with strong haematoprotective activity against nicotine-induced toxicity. In practical terms, this means that a diet rich in vitamin C and quercetin could prevent nicotine-induced toxicity and could also be useful in the supportive care of people exposed to nicotine.

Rationalization of a nanoparticle-based nicotine nanovaccine as an effective next-generation nicotine vaccine: A focus on hapten localization

A lipid-polymeric hybrid nanoparticle-based next-generation nicotine nanovaccine was rationalized in this study to combat nicotine addiction. A series of nanovaccines, which had nicotine-haptens localized on carrier protein (LPKN), nanoparticle surface (LPNK), or both (LPNKN), were designed to study the impact of hapten localization on their immunological efficacy. All three nanovaccines were efficiently taken up and processed by dendritic cells. LPNKN induced a significantly higher immunogenicity against nicotine and a significantly lower anti-carrier protein antibody level compared to LPKN and LPNK. Meanwhile, it was found that the anti-nicotine antibodies elicited by LPKN and LPNKN bind nicotine stronger than those elicited by LPKN, and LPNK and LPNKN resulted in a more balanced Th1-Th2 immunity than LPKN. Moreover, LPNKN exhibited the best ability to block nicotine from entering the brain of mice. Collectively, the results demonstrated that the immunological efficacy of the hybrid nanoparticle-based nicotine vaccine could be enhanced by modulating hapten localization, providing a promising strategy to combatting nicotine addiction.

Pharmacokinetics of nicotine following the controlled use of a prototype novel tobacco vapor product

The objective of this clinical study was to investigate the pharmacokinetics of nicotine following the use of a prototype novel tobacco vapor (PNTV) product in comparison to a conventional cigarette (CC1). The study was conducted in Japanese healthy adult male smokers, using an open-label, randomized, two-period crossover design, to assess the pharmacokinetics of nicotine after controlled use of a PNTV product or CC1. During the study period, blood samples were drawn from subjects for the measurement of plasma nicotine concentrations and nicotine intake was estimated from the mouth level exposure (MLE). The Cmax and AUClast following the use of PNTV product were 45.7% and 68.3%, respectively, of those obtained with CC1 and there were no significant differences in the tmax and t1/2 between PNTV product and CC1. The estimated MLE following the use of PNTV product was approximately two-thirds of that obtained following the smoking of CC1, but the relative bioavailability of PNTV product to CC1 was approximately 104%. The differences in Cmax and AUClast between PNTV product and CC1 therefore are explained by differences in nicotine intake. These results suggest that the PNTV product shows a similar pharmacokinetic profile to CC1, while delivering less nicotine following controlled use.

Construction of an enantiopure bivalent nicotine vaccine using synthetic peptides

Clinical outcomes of anti-nicotine vaccines may be improved through enhancements in serum antibody affinity and concentration. Two strategies were explored to improve vaccine efficacy in outbred mice: the use of enantiopure haptens and formulation of a bivalent vaccine. Vaccines incorporating natural (-) nicotine haptens improved relative antibody affinities >10-fold over (+) haptens, stimulated a two-fold boost in nicotine serum binding capacity, and following injection with 3 cigarette equivalents of nicotine, prevented a larger proportion of nicotine (>85%) from reaching the brain. The activity of a bivalent vaccine containing (-) 3’AmNic and (-) 1’SNic haptens was then compared to dose-matched monovalent groups. It was confirmed that antisera generated by these structurally distinct haptens have minimal cross-reactivity and stimulate different B cell populations. Equivalent antibody affinities were detected between the three groups, but the bivalent group showed two-fold higher titers and an additive increase in nicotine serum binding capacity as compared to the monovalent groups. Mice immunized with the bivalent formulation also performed better in a nicotine challenge experiment, and prevented >85% of a nicotine dose equivalent to 12 cigarettes from reaching the brain. Overall, enantiopure conjugate vaccines appear to improve serum antibody affinity, while multivalent formulations increase total antibody concentration. These findings may help improve the performance of future clinical candidate vaccines.

The Influence of a Mouthpiece-Based Topography Measurement Device on Electronic Cigarette User's Plasma Nicotine Concentration, Heart Rate, and Subjective Effects Under Directed and Ad Libitum Use Conditions

INTRODUCTION

Electronic cigarettes e-cigarettes aerosolize a liquid solution often containing nicotine. e-cigarette nicotine delivery may be influenced by user puffing behaviors ("puff topography"). E-cigarette puff topography can be recorded using mouthpiece-based computerized systems. The present study sought to examine the extent to which these systems influence e-cigarette nicotine delivery and other e-cigarette associated acute effects under ad libitum use conditions.

METHODS

Plasma nicotine concentration, heart rate, and subjective effects were assessed in 29 experienced e-cigarette users using their preferred e-cigarette battery and liquid (≥12mg/mL nicotine) in two sessions differing only by the presence of a mouthpiece-based device. In both sessions, participants completed a directed e-cigarette use bout (10 puffs, 30-s interpuff interval) and a 90-min ad libitum bout. Puff topography was recorded in the session with the topography mouthpiece.

RESULTS

Plasma nicotine, heart rate, and subjective effects, aside from "Did the e-cigarette Taste Good?" were independent of topography measurement (higher mean taste ratings were observed in the no topography condition). Mean (SEM) plasma nicotine concentration following the ad libitum bout was 34.3ng/mL (4.9) in the no topography condition and 35.7ng/mL (4.3) in the topography condition. Longer puff durations, longer interpuff intervals, and larger puff volumes were observed in the ad libitum relative to the directed bout.

CONCLUSIONS

E-cigarette use significantly increased plasma nicotine concentration and heart rate while suppressing abstinence symptoms. These effects did not differ when a topography mouthpiece was present. Future studies using ad libitum e-cigarette use bouts would facilitate understanding of e-cigarette toxicant yield.

IMPLICATIONS

No prior study has examined whether mouthpiece-based topography recording devices influence e-cigarette associated nicotine delivery, heart rate, or subjective effects under ad libitum conditions or assessed ad libitum puff topography in experienced individuals using their preferred e-cigarette battery and liquid with a mouthpiece-based computerized device. E-cigarette use significantly increased plasma nicotine concentration and heart rate while suppressing abstinence symptoms. These effects did not differ when a topography mouthpiece was present. Ad libitum puff topography differed from puff topography recorded during directed puffing. These findings suggest that future studies using ad libitum use bouts would facilitate better understanding of e-cigarette toxicant yield.

The Importance of Conditioned Stimuli in Cigarette and E-Cigarette Craving Reduction by E-Cigarettes

This study examined the impact of four variables pertaining to the use of e-cigarettes (e-cigs) on cravings for tobacco cigarettes and for e-cigs after an overnight abstinence period. The four variables were the nicotine level, the sensorimotor component, the visual aspect, and the aroma of the e-cig. In an experimental study, 81 participants without prior vaping experience first got acquainted with using e-cigs in a one-week tryout period, after which they participated in a lab session assessing the effect of five minutes of vaping following an abstinence period of 12 h. A mixed-effects model clearly showed the importance of nicotine in craving reduction. However, also non-nicotine factors, in particular the sensorimotor component, were shown to contribute to craving reduction. Handling cues interacted with the level (presence/absence) of nicotine: it was only when the standard hand-to-mouth action cues were omitted that the craving reducing effects of nicotine were observed. Effects of aroma or visual cues were not observed, or weak and difficult to interpret, respectively.

Reduced Exposure to Harmful and Potentially Harmful Smoke Constituents With the Tobacco Heating System 2.1

INTRODUCTION

Heating rather than burning tobacco reduces levels of harmful and potentially harmful constituents, and consumer products using this approach aim to reduce exposure to tobacco toxicants. The Tobacco Heating System (THS) version 2.1 has been enhanced from earlier prototypes with an improved heat control and sensorial experience and thereby user acceptance. Exposure measurements are required to determine whether it may be possible to reduce the individual health risk compared to smoking combustible cigarettes (CCs).

METHODS

This controlled clinical study randomly assigned 40 smokers to either a group continuing to use of their own CC brand (n = 20) or a group switching to THS 2.1 (n = 20) for 5 days. Biomarkers of exposure were measured at baseline and on day 1 through day 5. Product consumption, Human Puffing Topography, the occurrence of adverse events, and an assessment of subjective effects, such as smoking satisfaction and enjoyment of respiratory tract sensations, were also determined.

RESULTS

The group of smokers who switched to THS 2.1 adapted their puffing behavior initially through longer puff duration and more puffs. During the duration of the study, total puff volume returned to baseline levels and the mean daily product consumption increased but with similar nicotine exposure compared to baseline CC use. Biomarkers of exposure to tobacco smoke toxicants which inform product risk assessment were significantly reduced with THS use compared to the CC group. THS 2.1 users experienced less reinforcing effects with THS 2.1 than with their own cigarette brand.

CONCLUSIONS

THS 2.1 is a promising alternative to smoking CCs. Notwithstanding possible use adaption through consumption or puffing behavior, the exposure to harmful smoke constituents was markedly reduced with the new heated tobacco platform.

IMPLICATIONS

Exposure markers to harmful and potentially harmful smoke constituents were lowered with the THS 2.1. Heating tobacco instead of burning can offer a potentially lower risk of delivering nicotine compared to CCs.

E-cigarette Nicotine Delivery: Data and Learnings from Pharmacokinetic Studies

OBJECTIVES

E-cigarettes could potentially play a major role in tobacco harm reduction by delivering nicotine in a vapor containing significantly fewer toxicants than cigarette smoke and may aid smoking behavior changes such as reduction or cessation.

METHODS

We examined blood nicotine levels in smokers who were non-accustomed to e-cigarette use (Study 1) and accustomed e-cigarette users (Study 2). We compared nicotine levels when participants used a closed modular system e-cigarette to those when participants smoked a cigarette.

RESULTS

In Study 1, Cmax (geometric mean (CV)) during a 5-minute puffing period (10 puffs, 30 seconds apart) was 13.4 (51.4) ng/ ml for a regular cigarette. The e-cigarette Cmax was significantly lower (p .05) at 2.5 (67.8) ng/ml. In Study 2, during a 5-minute ad libitum puffing period, cigarette Cmax was 7.2 (130.8) ng/mL, and it was 7.8 (108.2) ng/mL for the e-cigarette.

CONCLUSIONS

Our data demonstrate heterogeneity of nicotine deliveries both between products and also with the same products used by different cohorts, eg, accustomed users versus smokers. Such differences must be taken into account when determining the likely behavioral impact, on smoking reduction and cessation, of nicotine delivery data and when planning e-cigarette nicotine pharmacokinetic studies.

Expanding clinical laboratory tobacco product evaluation methods to loose-leaf tobacco vaporizers

BACKGROUND

Novel tobacco products entering the US market include electronic cigarettes (ECIGs) and products advertised to "heat, not burn" tobacco. There is a growing literature regarding the acute effects of ECIGs. Less is known about "heat, not burn" products. This study's purpose was to expand existing clinical laboratory methods to examine, in cigarette smokers, the acute effects of a "heat, not burn" "loose-leaf tobacco vaporizer" (LLTV).

METHODS

Plasma nicotine and breath carbon monoxide (CO) concentration and tobacco abstinence symptom severity were measured before and after two 10-puff (30-s interpuff interval) product use bouts separated by 60min. LLTV effects were compared to participants' own brand (OB) cigarettes and an ECIG (3.3V; 1.5ohm; 18mg/ml nicotine).

RESULTS

Relative to OB, LLTV increased plasma nicotine concentration to a lesser degree, did not increase CO, and did not appear to reduce abstinence symptoms as effectively. Relative to ECIG, LLTV nicotine and CO delivery and abstinence symptom suppression did not differ. Participants reported that both the LLTV and ECIG were significantly less satisfying than OB.

CONCLUSIONS

Results demonstrate that LLTVs are capable of delivering nicotine and suppressing tobacco abstinence symptoms partially; acute effects of these products can be evaluated using existing clinical laboratory methods. Results can inform tobacco product regulation and may be predictive of the extent that these products have the potential to benefit or harm overall public health.

Simultaneous determination of nicotine, cotinine, and nicotine N-oxide in human plasma, semen, and sperm by LC-Orbitrap MS

Nicotine (Nic) distribution in human fluids and tissues has a deleterious effect on human health. In addition to its poisoning profile, Nic may contribute to the particular impact of smoking on human reproduction. Although present in seminal fluid, still nobody knows whether nicotine is available in sperm or not. Herein, we developed and validated a new bioanalytical method, for simultaneous determination of Nic, cotinine (Cot), and nicotine N'-oxide (Nox) in human plasma, semen, and sperm by LC-ESI-orbitrap-MS. Blood and semen samples were collected from 12 healthy smoking volunteers in this study. Sperm bodies were then separated quantitatively from 1 mL of semen samples by centrifugation. The developed method was fully validated for plasma following European and American guidelines for bioanalytical method validation, and partial validation was applied to semen analysis. Plasma, semen, and sperm samples were treated by trichloroacetic acid solution for protein direct precipitation in single extraction step. The established calibration range for Nic and Nox in plasma and semen was linear between 5 and 250 ng/mL, and for Cot between 10 and 500 ng/mL. Nic and Cot were detected in human sperm at concentrations as high as in plasma. In addition, Nox was present in semen and sperm but not in plasma. Graphical abstract Nicotine correlation between plasma and semen a; Nicotine correlation between semen and sperm c; Cotinine correlation between plasma and semen b; Cotinine correlation between semen and sperm d.

Group Waterpipe Tobacco Smoking Increases Smoke Toxicant Concentration

INTRODUCTION

Waterpipe tobacco smoking is a global health concern. Laboratory research has focused on individual waterpipe users while group use is common. This study examined user toxicant exposure and smoke toxicant yield associated with individual and group waterpipe smoking.

METHODS

Twenty-two pairs of waterpipe smokers used a waterpipe individually and as a dyad. Before and after smoking, blood was sampled and expired carbon monoxide (CO) measured; puff topography was recorded throughout. One participant from each pair was selected randomly and their plasma nicotine and expired air CO concentrations were compared when smoking alone to when smoking as part of a dyad. Recorded puff topography was used to machine-produce smoke that was analyzed for toxicant content.

RESULTS

There was no difference in mean plasma nicotine concentration when an individual smoked as part of a dyad (mean = 14.9 ng/ml; standard error of the mean [SEM] = 3.0) compared to when smoking alone (mean = 10.0 ng/ml; SEM = 1.5). An individual smoking as part of as a dyad had, on average, lower CO (mean = 15.8 ppm; SEM = 2.0) compared to when smoking alone (mean= 21.3 ppm; SEM = 2.7). When two participants smoked as a dyad they took, on average, more puffs (mean = 109.8; SEM = 7.6) than a singleton smoker (mean = 77.7; SEM = 8.1) and a shorter interpuff interval (IPI; dyad mean = 23.8 seconds; SEM = 1.9; singleton mean = 40.8 seconds; SEM = 4.8). Higher concentrations of several toxicants were observed in dyad-produced smoke.

DISCUSSION

Dyad smoking may increase smoke toxicant content, likely due to the dyad's shorter IPIs and greater puff number. More work is needed to understand if group waterpipe smoking alters the health risks of waterpipe tobacco smoking.

IMPLICATIONS

This study is the first to measure toxicants in smoke generated from a waterpipe when used by a dyad. Relative to smoke generated by a singleton, dyad smoke had higher concentration of some toxicants. These differences may be attributed to differences in puffing behavior, specifically the shorter IPI and greater puff number observed in the dyad condition. Relative to singleton smokers, dyad smokers were exposed to less CO, but nicotine exposure did not differ. More work is needed to assess the health effects of inhalation of more toxicant-laden smoke during group waterpipe use.

Prenatal nicotinic exposure upregulates pulmonary C-fiber NK1R expression to prolong pulmonary C-fiber-mediated apneic response

Prenatal nicotinic exposure (PNE) prolongs bronchopulmonary C-fiber (PCF)-mediated apneic response to intra-atrial bolus injection of capsaicin in rat pups. The relevant mechanisms remain unclear. Pulmonary substance P and adenosine and their receptors (neurokinin-A receptor, NK1R and ADA1 receptor, ADA1R) and transient receptor potential cation channel subfamily V member 1 (TRPV1) expressed on PCFs are critical for PCF sensitization and/or activation. Here, we compared substance P and adenosine in BALF and NK1R, ADA1R, and TRPV1 expression in the nodose/jugular (N/J) ganglia (vagal pulmonary C-neurons retrogradely labeled) between Ctrl and PNE pups. We found that PNE failed to change BALF substance P and adenosine content, but significantly upregulated both mRNA and protein TRPV1 and NK1R in the N/J ganglia and only NK1R mRNA in pulmonary C-neurons. To define the role of NK1R in the PNE-induced PCF sensitization, the apneic response to capsaicin (i.v.) without or with pretreatment of SR140333 (a peripheral and selective NK1R antagonist) was compared and the prolonged apnea by PNE significantly shortened by SR140333. To clarify if the PNE-evoked responses depended on action of nicotinic acetylcholine receptors (nAChRs), particularly α7nAChR, mecamylamine or methyllycaconitine (a general nAChR or a selective α7nAChR antagonist) was administrated via another mini-pump over the PNE period. Mecamylamine or methyllycaconitine eliminated the PNE-evoked mRNA and protein responses. Our data suggest that PNE is able to elevate PCF NK1R expression via activation of nAChRs, especially α7nAChR, which likely contributes to sensitize PCFs and prolong the PCF-mediated apneic response to capsaicin.

Nicotine delivery, tolerability and reduction of smoking urge in smokers following short-term use of one brand of electronic cigarettes

BACKGROUND

This randomized, partially single-blinded, 6-period crossover clinical study of adult smokers compared the nicotine pharmacokinetics, impacts on smoking urge and tolerability of various formulations of one brand of e-cigarettes with that of a tobacco cigarette.

METHODS

Five e-cigarettes with different e-liquid formulations containing 1.6 % and 2.4 % nicotine and a conventional tobacco cigarette were randomized among 24 subjects under two exposure sessions consisting of a 30-min controlled and a one-hour ad lib use period to assess plasma nicotine levels, impacts on smoking urge and adverse events. The 30-min controlled use session comprised an intensive use of the e-cigarettes with a total of 50 puffs taken every 30 s for comparison to a single conventional cigarette having a typical machine-measured nicotine yield (~0.8 mg). Ad lib product use conditions provided insight into more naturalistic product use behaviors and their accompanying smoking urge reductions. Adverse events (AEs) were assessed by the Principal Investigator.

RESULTS

Significant (p < 0.05) increases in plasma nicotine concentrations occurred within 10 min of controlled e-cigarette use and significant (p < 0.001) reductions from baseline smoking urge were observed within 5 min. E-cigarette and cigarette nicotine plasma levels were comparable for up to one hour of use. After both sessions (90 min), nicotine exposure was the highest for the cigarette, with all e-cigarettes showing 23 % to 53 % lower plasma concentrations. During controlled use, peak reduction in smoking urge for e-cigs occurred later than for the cigarette. After completion of both sessions, significant smoking urge reduction persisted for most of the tested e-cigarettes, albeit at levels lower than that provided by the tobacco cigarette. Nicotine content, vehicle differences, and the presence of menthol did not significantly affect smoking urge reduction by the e-cigarettes. No subjects were discontinued due to AEs. The most frequently reported AEs events included cough, throat irritation, headache, and dizziness.

CONCLUSIONS

Blood plasma nicotine levels obtained from short-term use of e-cigarettes containing 1.6 % and 2.4 % nicotine were significant, but lower than those of conventional tobacco cigarettes, yet the reduction in craving symptoms were broadly comparable. The types of AEs were consistent with other research studies of longer duration that have reported that use of e-cigarettes by adult smokers is well-tolerated.

TRIAL REGISTRATION

http://ClinicalTrials.gov identifier: NCT02210754 . Registered 8 August 2014.

Effects of Menthol on Nicotine Pharmacokinetic, Pharmacology and Dependence in Mice

Although menthol, a common flavoring additive to cigarettes, has been found to impact the addictive properties of nicotine cigarettes in smokers little is known about its pharmacological and molecular actions in the brain. Studies were undertaken to examine whether the systemic administration of menthol would modulate nicotine pharmacokinetics, acute pharmacological effects (antinociception and hypothermia) and withdrawal in male ICR mice. In addition, we examined changes in the brain levels of nicotinic receptors of rodents exposed to nicotine and menthol. Administration of i.p. menthol significantly decreased nicotine’s clearance (2-fold decrease) and increased its AUC compared to i.p. vehicle treatment. In addition, menthol pretreatment prolonged the duration of nicotine-induced antinociception and hypothermia (2.5 mg/kg, s.c.) for periods up to 180 min post-nicotine administration. Repeated administration of menthol with nicotine increased the intensity of mecamylamine-precipitated withdrawal signs in mice exposed chronically to nicotine. The potentiation of withdrawal intensity by menthol was accompanied by a significant increase in nicotine plasma levels in these mice. Western blot analyses of α4 and β2 nAChR subunit expression suggests that chronic menthol impacts the levels and distribution of these nicotinic subunits in various brain regions. In particular, co-administration of menthol and nicotine appears to promote significant increase in β2 and α4 nAChR subunit expression in the hippocampus, prefrontal cortex and striatum of mice. Surprisingly, chronic injections of menthol alone to mice caused an upregulation of β2 and α4 nAChR subunit levels in these brain regions. Because the addition of menthol to tobacco products has been suggested to augment their addictive potential, the current findings reveal several new pharmacological molecular adaptations that may contribute to its unique addictive profile.

The effects of smoked nicotine on measures of subjective states and hypothalamic-pituitary-adrenal axis hormones in women during the follicular and luteal phases of the menstrual cycle

OBJECTIVES

To determine the acute effects of cigarette smoking on hypothalamic-pituitary-adrenal (HPA) axis hormones and subjective states as a function of the menstrual cycle in nicotine-dependent women.

METHODS

Seventeen healthy nicotine-dependent women were studied during the follicular and/or luteal phase of the menstrual cycle. Because of observation of a possible bimodal distribution of progesterone levels within the luteal phase group, we performed a set of a posteriori analyses. Therefore, we divided the luteal group into a low progesterone and a high progesterone groups.

RESULTS

Smoked nicotine activated HPA, measured by adrenocorticotropin hormone (ACTH), cortisol, and dehydroepiandrosterone (DHEA) response and affected subjective states in both follicular and luteal phases, with increased "High," "Rush," and decreased "Craving." The HPA stimulation revealed a blunting of ACTH response. There was only modest evidence for a blunting of subjective state responses in the luteal phase. However, upon post hoc analyses, the high progesterone luteal group showed a marked blunting of measures of subjective states and a blunted ACTH response. Examining the association between hormone and measures of subjective states revealed tentative associations of ACTH stimulation with increased "Rush" and "Craving," and DHEA stimulation with increased "Craving."

CONCLUSIONS

This pilot study suggests that menstrual cycle phase differences in progesterone levels may attenuate nicotine's addictive effects via diminution of its reinforcing properties and augmentation of its aversive effects interfering with the pleasure associated with cigarette smoking.

Test-Retest Reliability and Stability of the Nicotine Metabolite Ratio Among Treatment-Seeking Smokers

INTRODUCTION

The nicotine metabolite ratio (NMR), the ratio of 3-hydroxycotinine to cotinine, is a biomarker used in smoking cessation research, with several retrospective studies suggesting that NMR predicts treatment outcome. To be maximally useful in tailoring treatment, estimates of NMR should be stable over time. The present study is the first to examine the short-term test-retest reliability of NMR among treatment-seeking smokers.

METHODS

Blood NMR was assessed at two time points, approximately 2-3 weeks apart and prior to intervention, among 72 healthy adult smokers (49% female; 35% non-White) enrolled in a cessation trial (http://ClinicalTrials.gov ID: NCT01314001).

RESULTS

Mean NMR was stable from Time-1 to Time-2, with no significant change between assessments; test-retest reliability for NMR values was excellent (ICC[2,1] = 0.87). Test-retest reliability remained acceptable to high when NMR was categorized, as in recent clinical trials. Classification of participants as slow (quartile 1, NMR ≤ 0.24) or normal/fast NMR (quartiles 2-4, NMR ≥ 0.25) was consistent from Time-1 to Time-2 for 96% of participants (κ = 0.89). Though classification of participants into NMR quartiles was less consistent from Time-1 to Time-2 (67% agreement; weighted κ = 0.73), all reclassifications occurred between adjacent quartiles.

CONCLUSIONS

Overall, these data support the use of a single NMR assessment for association studies with smoking phenotypes and in smokers seeking to quit, and they encourage large-scale efforts to determine optimal NMR cutpoints for tailoring treatment selection.

Evaluation of a novel nicotine inhaler device: part 2--effect on craving and smoking urges

INTRODUCTION

Many smokers find currently available nicotine replacement therapies unsatisfactory. The pharmacokinetics of nicotine delivered via a novel inhaler device, and its effect on craving satiation and smoking urges, were compared with the Nicorette® Inhalator (10 mg).

METHODS

Results are reported for Parts B (N = 24) and D (N = 24) of a 4-part Phase I study. Participants (18-55 years, ≥ 10 cigarettes/day within 1 hr of waking, expired carbon monoxide >10 ppm on screening) received single doses of nicotine on consecutive days (0.45 and 0.67 mg [Part B] and 0.45 mg [Part D] via the novel device; 10 mg via Nicorette® [Parts B and D]). Venous pharmacokinetics, craving, and tolerability were assessed.

RESULTS

In Part B, the novel device 0.45 and 0.67 mg produced significantly lower C max, AUClast, and AUCall than Nicorette® (all p ≤ .05), higher AUC0-10 and significantly shorter T max (18.7 and 19.2 min vs. 38.0 min, respectively, p ≤ .05). Craving score AUC was lower for the novel device 0.45 mg than for Nicorette® in Part B (1356.3 vs. 1566.3, p = .029) and approached statistical significance in Part D (1208.5 vs. 1402.3 [p = .059]). Mean craving scores were lower for the novel device 0.45 mg than Nicorette® at 7/8 postdose timepoints in Part B (p ≤ .05 at 180 and 240 min) and at all timepoints in Part D (p ≤ .05 at 2, 4, and 10 min).

CONCLUSIONS

The novel device was at least as effective as the Nicorette® Inhalator (10mg) in relieving craving and smoking urges and was statistically superior at certain timepoints and in an overall craving AUC analysis, despite lower total nicotine exposure.

Mu Opioid Receptor Binding Correlates with Nicotine Dependence and Reward in Smokers

The rewarding effects of nicotine are associated with activation of nicotine receptors. However, there is increasing evidence that the endogenous opioid system is involved in nicotine's rewarding effects. We employed PET imaging with [¹¹C]carfentanil to test the hypotheses that acute cigarette smoking increases release of endogenous opioids in the human brain and that smokers have an upregulation of mu opioid receptors (MORs) when compared to nonsmokers. We found no significant changes in binding potential (BP_ND) of [¹¹C]carfentanil between the placebo and the active cigarette sessions, nor did we observe differences in MOR binding between smokers and nonsmokers. Interestingly, we showed that in smokers MOR availability in bilateral superior temporal cortices during the placebo condition was negatively correlated with scores on the Fagerström Test for Nicotine Dependence (FTND). Also in smokers, smoking-induced decreases in [¹¹C]carfentanil binding in frontal cortical regions were associated with self-reports of cigarette liking and wanting. Although we did not show differences between smokers and nonsmokers, the negative correlation with FTND corroborates the role of MORs in superior temporal cortices in nicotine addiction and provides preliminary evidence of a role of endogenous opioid signaling in frontal cortex in nicotine reward.

Use of meconium in perinatal epidemiology: potential benefits and pitfalls

PURPOSE

Meconium is a biomarker matrix that can be used to assess cumulative exposures in epidemiologic studies of prenatal risk factors. Depending on when meconium is collected, different exposure windows during pregnancy can be measured. However, little guidance exists regarding the extent to which timing of meconium collection will influence resulting effect estimates.

METHODS

We performed a simulation study of prenatal tobacco smoke exposure (assessed from meconium nicotine) and birth weight. We discuss four typical meconium collection methods capturing different exposure windows and assess the biases induced by these methods.

RESULTS

In simulations assuming that exposure to tobacco smoke only during late gestation was of etiologic relevance to birth weight, use of a meconium collection method that captured exposure windows other than late gestation resulted in biased estimates of the true nicotine-birth weight association.

CONCLUSIONS

Using meconium collection methods that do not reflect an exposure window of etiologic relevance can lead to biased results and erroneous conclusions regarding the nature of prenatal exposure-outcome associations. Understanding how prenatal exposure patterns vary across the pregnancy and exposure windows of etiologic relevance is essential in determining when and how to collect meconium for use in biomarker studies of prenatal exposure.

Nicotine blood levels and short-term smoking reduction with an electronic nicotine delivery system

OBJECTIVES

To evaluate nicotine delivery from the NJOY® King Bold Electronic Nicotine Delivery System (ENDS) and its short-term potential for smoking reduction or cessation.

METHODS

One week of ad libitum use was followed by measurements of plasma nicotine, heart rate, and craving and withdrawal after 12 hours of nicotine abstinence in 25 adult smokers not interested in quitting.

RESULTS

After 5 minutes of use, blood nicotine levels increased by a mean of 3.5 ng/mL (p < .001), heart rate increased, and craving was reduced by 55%. Cigarettes per day were reduced by 39% during the test week, and perceptions of use for reduction or cessation were positive.

CONCLUSIONS

The NJOY® King Bold ENDS delivers nicotine and led to short-term smoking reduction.

Toxicological evaluation of aerosols of a tobacco extract formulation and nicotine formulation in acute and short-term inhalation studies

A formulation of tobacco extract containing 4% nicotine (TE) and similar nicotine formulation containing vehicle and 4% nicotine (NF) were evaluated using animal inhalation assays. Two 4-h inhalation exposures at 1 and 2 mg/L aerosol exposure concentrations, respectively, of the tobacco extract with 4% nicotine formulation showed that the LC50 was greater than 2 mg/L, the maximum concentration tested. All inhalation exposures were conducted using the capillary aerosol generator (CAG). Increasing aerosol TPM concentrations (0, 10, 50, 200, 1000 mg/m(3) TE and 0, 50, 200, 500, 1000 mg/m(3) NF) were generated via the CAG and used to expose groups of male and female rats for 4-h per day for 14 days. In life monitors for potential effects included clinical observations, weekly body weights and food consumption. Post mortem evaluations included gross tissue findings, hematology, clinical chemistry, serum plasma and nicotine levels, absolute and normalized organ and tissue weights, and histopathology of target organs. Treatment-related changes were observed in body weights, hematology, clinical chemistry, organ weights and histopathological findings for TE at the 200 and 1000 mg/m(3) exposure levels, and in the 500 and 1000 mg/m(3) exposure groups for NF. Under the conditions of these studies, the no-observed-adverse-effect level in the rat was approximately 50 mg/m(3) for the TE aerosol-exposed groups, and approximately 200 mg/m(3) in the NF aerosol-exposed groups.

Effects of intravenous nicotine on prepulse inhibition in smokers and non-smokers: relationship with familial smoking

RATIONALE

The reinforcing properties of nicotine may be, in part, derived from its ability to enhance certain forms of cognitive processing. Several animal and human studies have shown that nicotine increases prepulse inhibition (PPI) of the startle reflex. However, it remains unclear whether these effects are related to smoking susceptibility.

OBJECTIVES

The current study examined the effects of intravenously delivered nicotine on PPI in smokers and non-smokers, as well as its association with a quantitative index of familial smoking.

METHODS

The sample consisted of 30 non-smokers and 16 smokers, who completed an initial assessment, followed on a separate day by a laboratory assessment of PPI prior to and following each of two intravenous nicotine infusions. Separate doses were used in smoker and non-smoker samples.

RESULTS

Analyses indicated that both nicotine infusions acutely enhanced PPI among non-smokers, and this enhancement was positively related to the degree of smoking among first and second-degree relatives. Smokers also displayed PPI enhancement after receiving the first infusion, but this effect was unrelated to familial smoking.

CONCLUSIONS

These data suggest that the PPI paradigm may have utility as an endophenotype for cognitive processes which contribute to smoking risk.