Introduction Electronic cigarettes’ (e-cigarettes) viability as a public health strategy to end smoking will likely be determined by their ability to mimic the pharmacokinetic profile of a cigarette while also exposing users to significantly lower levels of harmful/potentially harmful constituents (HPHCs). The present study examined the nicotine delivery profile of third- (G3) versus second-generation (G2) e-cigarette devices and their users’ exposure to nicotine and select HPHCs compared with cigarette smokers. Methods 30 participants (10 smokers, 9 G2 and 11 G3 users) completed baseline questionnaires and provided exhaled carbon monoxide (eCO), saliva and urine samples. Following a 12-hour nicotine abstinence, G2 and G3 users completed a 2-hour vaping session (ie, 5 min, 10-puff bout followed by ad libitum puffing for 115 min). Blood samples, subjective effects, device characteristics and e-liquid consumption were assessed. Results Smokers, G2 and G3 users had similar baseline levels of cotinine, but smokers had 4 and 7 times higher levels of eCO (p<0.0001) and total 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (i.e., NNAL, p<0.01), respectively, than G2 or G3 users. Compared with G2s, G3 devices delivered significantly higher power to the atomiser, but G3 users vaped e-cigarette liquids with significantly lower nicotine concentrations. During the vaping session, G3 users achieved significantly higher plasma nicotine concentrations than G2 users following the first 10 puffs (17.5 vs 7.3 ng/mL, respectively) and at 25 and 40 min of ad libitum use. G3 users consumed significantly more e-liquid than G2 users. Vaping urges/withdrawal were reduced following 10 puffs, with no significant differences between device groups. Discussion Under normal use conditions, both G2 and G3 devices deliver cigarette-like amounts of nicotine, but G3 devices matched the amount and speed of nicotine delivery of a conventional cigarette. Compared with cigarettes, G2 and G3 e-cigarettes resulted in significantly lower levels of exposure to a potent lung carcinogen and cardiovascular toxicant. These findings have significant implications for understanding the addiction potential of these devices and their viability/suitability as aids to smoking cessation.

The current study is the first to examine flavours in WP smoking by measuring preferred versus control preparations to understand the impact on subjective experience, smoking behaviour and toxicant exposure. The pattern of results suggests that even this relatively minor manipulation resulted in significant changes in subjective experience. These results indicate a possible need for regulations restricting flavours in WP tobacco as with combustible cigarettes.

Background Recruitment and retention of participants are important factors in empirical studies. Methods that increase recruitment and retention can reduce costs and burden on researchers related to the need for over-recruitment because of attrition. Rideshare services such as Uber and Lyft are a potential means for decreasing this burden. Objective This study aimed to understand the role rideshare utilization plays in participant recruitment and retention in research trials. Methods Data are presented for a study ( N =42) in which rideshare services were utilized for participant transportation to and from study visits during a 2-session, in-laboratory research study. Results Retention at visit 2 was greater than 95% (42/44) in the initial study. In a follow-up survey of the participants from the original trial, participants (N=32) reported that the rideshare service was an important reason they returned for all study visits. Participants reported whether they would prefer differing levels of additional monetary compensation or a ride from a rideshare service. When the additional compensation was less than US $15, participants reported a preference for the rideshare service. Conclusions Rideshare services may represent a relatively low cost means for increasing study retention. Specifically, findings indicate that rideshare services may not be crucial for initial participant recruitment but for their retention in multi-visit studies.

Introduction Relative to non-waterpipe (WP) smokers, WP smokers are more than twice as likely to use alcohol and frequently consume alcohol before or during smoking sessions. Co-use of alcohol and WP may result in greater toxicant exposure compared to WP smoking alone. To date, no study systematically has investigated the impact of acute alcohol intoxication on WP smoking topography, exposure to tobacco-related toxicants, or abuse liability. Methods Dyads of current WP smokers and drinkers (N = 42; age = 21–32 years) completed two in-laboratory ad libitum smoking sessions (≤2 hours) following 12-hour nicotine abstinence in a double-blind, randomized crossover design in which they consumed a placebo versus active drink (sustained breath alcohol concentration = .08). Exhaled carbon monoxide (eCO) and plasma nicotine concentration were assessed. Questionnaires assessed smoking experience and smoking urge. Smoking topography was measured continuously throughout each smoking session. Results The alcohol session was associated with increased inhaled volume, flow rate, and WP session duration compared to placebo. Compared to placebo, participants reported a more positive overall smoking experience following the alcohol session and greater smoking urges pre- and post-smoking session. Although both sessions resulted in significant increases in eCO and plasma nicotine, no significant differences emerged in eCO or nicotine exposure between the active and placebo sessions. Conclusions Co-use of alcohol and WP may contribute to the maintenance of WP smoking through enhanced smoking experiences, increased urge to smoke, and significant exposure to addictive nicotine. Regulations may be necessary to limit the sale of alcohol in WP smoking lounges and reduce exposure to secondhand smoke. Implications The findings suggest co-use of alcohol and WP tobacco likely maintain WP use and dependence by enhancing the smoking experience and increasing urges to smoke. These findings have implications for regulations aimed at limiting co-use of alcohol and WP tobacco in WP lounges and limiting exposure to secondhand smoke. Clinical trials registration NCT03096860

BACKGROUND Recruitment and retention of participants are important factors in empirical studies. Methods that increase recruitment and retention can reduce costs and burden on researchers related to the need for over-recruitment because of attrition. Rideshare services such as Uber and Lyft are a potential means for decreasing this burden. OBJECTIVE This study aimed to understand the role rideshare utilization plays in participant recruitment and retention in research trials. METHODS Data are presented for a study (N=42) in which rideshare services were utilized for participant transportation to and from study visits during a 2-session, in-laboratory research study. RESULTS Retention at visit 2 was greater than 95% (42/44) in the initial study. In a follow-up survey of the participants from the original trial, participants (N=32) reported that the rideshare service was an important reason they returned for all study visits. Participants reported whether they would prefer differing levels of additional monetary compensation or a ride from a rideshare service. When the additional compensation was less than US $15, participants reported a preference for the rideshare service. CONCLUSIONS Rideshare services may represent a relatively low cost means for increasing study retention. Specifically, findings indicate that rideshare services may not be crucial for initial participant recruitment but for their retention in multi-visit studies.