Electronic nicotine delivery systems (ENDS) heat and vaporize a nicotine-containing liquid to produce an aerosol that can deliver nicotine to the blood and the brain. ENDS use has increased rapidly in the last decade, especially among youth: over 20% of US high school students are current ENDS users, and there is evidence of nicotine dependence in this population. Federal legislation has been proposed that would restrict ENDS liquid nicotine concentration to make ENDS "significantly less addictive and appealing to youth." However, these and other efforts to curb addiction by limiting nicotine liquid concentration are unlikely to succeed because nicotine emissions from ENDS depend on multiple variables. To achieve the intended public health aims, regulations targeting addiction must focus on nicotine delivery, not nicotine concentration. While nicotine delivery cannot be regulated directly, the rate at which an ENDS emits nicotine, the "nicotine flux", can be regulated and, importantly, predicted based on a few device design and operating variables. However, to date there is no empirical evidence demonstrating the relationship between flux and delivery, nor between flux and the subjective effects that support nicotine dependence. Closing this gap is essential for providing an effective framework for regulating ENDS. At the American University of Beirut, the investigators will assess the relationship between nicotine flux, form, and subjective effects. Participants will use ENDS devices with varying nicotine fluxes and forms. Dependency measures, such as urge to smoke, craving, and abstinence, will be assessed. The outcome will indicate the degree to which nicotine flux/form influence subjective effects related to dependency, puffing intensity, and exposure to toxicants. In summary, this project will provide the empirical evidence needed for public health agencies to use nicotine flux as an encompassing and convenient construct to regulate nicotine delivery from ENDS.
Assess the influence of nicotine flux and nicotine form on subjective effects. At AUB, the investigators will assess subjective effects (e.g. product liking, nicotine craving) and puffing topography for 130 participants who will undergo 5 ENDS use sessions (combinations 1-5) consisting of 2 bouts (10 puffs + 60min ad libitum) with 2 fluxes (15 and 35μg/s) x 2 forms (protonated, freebase) and a 0 nicotine condition. In addition, the investigators will use a state-of-the-art device to sample in situ a fraction of the aerosol generated during each puff to verify actual nicotine flux and form, and measure exposure to pulmonary toxicants (carbonyls). The investigators hypothesize that increasing nicotine flux and protonated nicotine will result in greater reductions of nicotine craving, and lower puffing intensity and carbonyl exposure. 10 of the participants that completed AIM 2 will be asked to attend our lab at AUB for one additional visit, where they will be assigned either a high flow or low flow ENDS. During the visit, participants will undertake three smoking bouts consisting of 10 puffs each, where they will be presented with alternating puffs of the assigned device in which a specific ENDS design variable is systematically varied between puffs. Puff topography, inhalation behavior, and subjective effects related to sensory feedback will be recorded. We hypothesize that power and liquid composition variations will result in immediate and reversible changes in puffing/inhalation behavior.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
142
30/70 propylene glycol/vegetable glycerin ratio with nicotine concentration 4mg/ml protonated
30/70 PG/VG ratio with nicotine concentration 10mg/ml protonated
30/70 PG/VG ratio with nicotine concentration 4mg/ml free base
30/70 PG/VG ratio with nicotine concentration 10mg/ml freebase
30/70 PG/VG ratio with nicotine concentration 0mg/ml (placebo)
30/70 PG/VG ratio with nicotine concentration 0mg/ml
e-liquid 7: 30/70 PG/VG ratio with nicotine concentration 4mg/ml protonated e-liquid 8: 30/70 PG/VG ratio with nicotine concentration 8mg/ml protonated
e-liquid 9: 30/70 PG/VG ratio with nicotine concentration 4mg/ml protonated e-liquid 10: 70/30 PG/VG ratio with nicotine concentration 4mg/ml protonated
American University of Beirut
Beirut, Beirut, Lebanon
Subjective Effects - Strong Flavor (Combinations 1-5)
Strong flavor will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled magnitude scale (gLMS) on a subjective scale (0-10, No sensation - Strongest Imaginable), with higher scores indicating a stronger perceived flavor.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Harshness/Irritancy (Combinations 1-5)
Harshness/irritancy will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled magnitude scale (gLMS) on a subjective scale (0-10, No sensation - Strongest Imaginable), with higher scores indicating harsher/more irritating effects.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Throat Hit (Combinations 1-5)
Throat hit will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled magnitude scale (gLMS) on a subjective scale (0-10, No sensation - Strongest Imaginable), with higher scores indicating a stronger throat hit.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Overall Like: Flavor (Combinations 1-5)
Overall like: flavor will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled hedonic scale (LHS) on a subjective scale (0-10, most disliked - most liked), with higher scores indicating the flavor was liked more.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Overall Like: Harshness (Combinations 1-5)
Overall like: harshness will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled hedonic scale (LHS) on a subjective scale (0-10, most disliked - most liked), with higher scores indicating the harshness was liked more.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Overall Like: Throat Hit (Combinations 1-5)
Overall like: throat hit will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled hedonic scale (LHS) on a subjective scale (0-10, most disliked - most liked), with higher scores indicating the throat hit was liked more.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Overall Like: Warmth (Combinations 1-5)
Overall like: warmth will be assessed by the Electronic Cigarette Specific Effects questionnaire, general labeled hedonic scale (LHS) on a subjective scale (0-10, most disliked - most liked), with higher scores indicating the warmth was liked more.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Satisfying (Combinations 1-5)
Satisfying will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating greater satisfaction.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Pleasant (Combinations 1-5)
Pleasant will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating greater pleasantness.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Taste Good (Combinations 1-5)
Taste good will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating better taste.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Calm (Combinations 1-5)
Calm will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating feeling calmer.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Concentrate (Combinations 1-5)
Concentrate will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating better ability to concentrate.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Awake (Combinations 1-5)
Awake will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating feeling more awake/alert.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Reduce Hunger (Combinations 1-5)
Reduce hunger will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating greater reduction in hunger.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Dizzy (Combinations 1-5)
Dizzy will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating greater dizziness.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Feeling Sick (Combinations 1-5)
Feeling sick will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating feeling more sick.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Want it Right Now (Combinations 1-5)
Want it right now will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating a stronger immediate desire for the product.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Smell (Combinations 1-5)
Smell will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating a stronger perceived smell. This item is drawn from the Electronic Cigarette Specific Effects Questionnaire, a modified/expanded version of the modified Cigarette Evaluation Questionnaire (mCEQ; Cappelleri et al., 2007) developed for ENDS. Participants rate the item on a 0-10 scale immediately following each bout. Item wording: 'Did the e-cig produce a smell?' (0 = not at all, 10 = extremely).
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Visible Vapor (Combinations 1-5)
Visible vapor will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating more visible vapor.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Importance Vapor (Combinations 1-5)
Importance vapor will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating vapor visibility mattered more to the participant. This item is drawn from the Electronic Cigarette Specific Effects Questionnaire, a modified/expanded version of the modified Cigarette Evaluation Questionnaire (mCEQ; Cappelleri et al., 2007) developed for ENDS. Participants rate the item on a 0-10 scale immediately following each bout. Item wording: 'Is the vapor/cloud of the e-cig important to you?' (0 = not at all, 10 = extremely).
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Subjective Effects - Puffs Similar (Combinations 1-5)
Puffs similar will be assessed by the Electronic Cigarette Specific Effects questionnaire and consists of 1 item scored 0 - 10 with 0 being not at all and 10 being extremely, with higher scores indicating the puffs were perceived as more similar to the participant's usual product.
Time frame: Post Bout 1: assessed 5 minutes after onset of the directed 10-puff bout (average bout duration ~5 minutes). Post Bout 2: assessed 5 minutes after onset of the 60-minute ad libitum bout.
Smoking Urges - Brief Factor 1 (Intention/Desire)
Brief Factor 1 (Intention/Desire) will be assessed by the Questionnaire of Smoking Urges-Brief (QSU-Brief; Tiffany \& Drobes, 1991; Toll et al., 2006). Factor 1 is the sum of 6 items, each rated on a 0-10 scale (0=strongly disagree, 10=strongly agree), yielding a total score range of 0-60, with higher scores indicating stronger urges.
Time frame: Assessed before and after the directed bout (Bout 1), and before, midway through, and after the ad libitum bout (Bout 2).
Smoking Urges - Brief Factor 2 (Relief of Neg. Affect)
Brief Factor 2 (Relief of Neg. Affect) will be assessed by the Questionnaire of Smoking Urges-Brief (QSU-Brief; Tiffany \& Drobes, 1991; Toll et al., 2006). Factor 2 is the sum of 4 items, each rated on a 0-10 scale (0=strongly disagree, 10=strongly agree), yielding a total score range of 0-40, with higher scores indicating stronger urges.
Time frame: Assessed before and after the directed bout (Bout 1), and before, midway through, and after the ad libitum bout (Bout 2).
Withdrawal Symptoms - Minnesota Nicotine Withdrawal Scale (MNWS; Based on Hughes and Hatsukami, 1986)
The Minnesota Nicotine Withdrawal Scale (MNWS; based on Hughes and Hatsukami, 1986 questionnaire) was measured using composite mean of MNWS items (irritability, anxiety, difficulty concentrating, restlessness, hunger/appetite, Impatient, depression, desire for sweets and craving) on a 0-10 scale (Not at all - Extremely), with higher scores indicating greater withdrawal severity.
Time frame: Assessed before and after the directed bout (Bout 1), and before, midway through, and after the ad libitum bout (Bout 2).
Puff Duration
Puff duration combination 1,2,3,4 \& 5
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
Number of Puffs
Measured topography Total Number of Puffs (puffs).
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
Puffing Time
Measured topography Average Puffing time (sec).
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
Inter Puff Interval
Measured topography Average Inter Puff Interval (sec).
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
Flow Rate
Measured topography Average Flow rate (Liters per minute: LPM).
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
Mouth-level PM
Mouth-level PM (Particulate matter) dose estimated using the REALTIME real-time in-situ sampling device, which collects 5% of the aerosol at the mouthpiece during each puff; values are reported as the total session dose (5% fraction × 20), in mg.
Time frame: Will be measured after the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
Mouth-level Nicotine
Mouth-level nicotine dose estimated using the REALTIME real-time in-situ sampling device, which collects 5% of the aerosol at the mouthpiece during each puff; values are reported as the total session dose (5% fraction × 20), in mg.
Time frame: Will be measured after the approximately 5-minute, 10-puff use bout and 60-minute, ad lib use bout
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Puff Duration - Combination 6,7 & 8
Measured topography Average Puff Duration (sec) - using Subox mini C. Puffs were administered in alternating order using block randomization; for Combination Six, odd puffs were delivered at 20W and even puffs at 40W; for Combination Seven, odd puffs were delivered at 20W/8mg/mL and even puffs at 40W/4mg/mL; for Combination Eight, odd puffs were delivered at 30/70 PG/VG and even puffs at 70/30 PG/VG.
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout
Sensory Feedback - Perceived Mouthful - Using Kangertech Subox Mini C (Sub-ohm Device)
The perceived mouthful will be assessed using the following question: "How would you rate the amount of smoke filling your mouth during the puff you just smoked?". A subjective visual analog scale will be used (1-5, barely any smoke- a lot of smoke) with higher scores indicating higher mouthful. Puffs were administered in alternating order using block randomization; for Combination Six, odd puffs were delivered at 20W and even puffs at 40W; for Combination Seven, odd puffs were delivered at 20W/8mg/mL and even puffs at 40W/4mg/mL; for Combination Eight, odd puffs were delivered at 30/70 PG/VG and even puffs at 70/30 PG/VG.
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout
Sensory Feedback - Perceived Draw Effort - Using Kangertech Subox Mini C (Sub-ohm Device)
The perceived draw effort will be assessed using the following question: " How would you rate the effort needed to draw the puff you just smoked?". A subjective visual analog scale will be used (1-5, easy- hard) with higher scores indicating harder draw effort. Puffs were administered in alternating order using block randomization; for Combination Six, odd puffs were delivered at 20W and even puffs at 40W; for Combination Seven, odd puffs were delivered at 20W/8mg/mL and even puffs at 40W/4mg/mL; for Combination Eight, odd puffs were delivered at 30/70 PG/VG and even puffs at 70/30 PG/VG.
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout
Sensory Feedback - Throat Hit - Using Kangertech Subox Mini C (Sub-ohm Device)
The perceived Throat hit will be assessed using the following question: "How would you describe the throat hit of the device you just used" (0-100 General Labeled Magnitude Scale; anchors: "barely detectable" to "strongest imaginable"). Puffs were administered in alternating order using block randomization; for Combination Six, odd puffs were delivered at 20W and even puffs at 40W; for Combination Seven, odd puffs were delivered at 20W/8mg/mL and even puffs at 40W/4mg/mL; for Combination Eight, odd puffs were delivered at 30/70 PG/VG and even puffs at 70/30 PG/VG.
Time frame: Will be measured during the approximately 5-minute, 10-puff use bout