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

Abstract

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.

Full text

Vol.:(0123456789)
1 3
Internal and Emergency Medicine
https://doi.org/10.1007/s11739-019-02025-3
IM - ORIGINAL
A randomised, open‑label, cross‑over clinical study toevaluate
thepharmacokinetic proles ofcigarettes ande‑cigarettes
withnicotine salt formulations inUS adult smokers
GrantO’Connell1· JohnD.Pritchard1· ChrisPrue1· JosephThompson1· ThomasVerron1· DonaldGra2·
TanvirWalele1
Received: 4 October 2018 / Accepted: 2 January 2019
© The Author(s) 2019
Abstract
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 phar-
macokinetics, 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.
Keywords Conventional cigarette· Electronic cigarette· E-cigarette· Pharmacokinetics· Nicotine delivery· Nicotine salt·
Nicotine lactate
Introduction
According to Public Health England and the Royal College
of Physicians, electronic cigarettes (e-cigarettes) are likely to
be at least 95% less harmful than conventional cigarettes [1,
2]. This view was recently reaffirmed, with a further com-
ment from Public Health England that e-cigarettes pose only
a fraction of the harms that smoking does, and that smokers
should be encouraged to switch [3]. Continuing to recognise
that complete cessation of all tobacco and nicotine use as
the best action smokers can take to improve their health,
Public Health England and the Royal College of Physicians
are clear that encouraging and assisting smokers who are
neither interested nor willing to quit smoking to switch to
using nicotine products that are substantially less harmful
than inhaled tobacco smoke is the next best option to help
stop smoking [2, 3].
A growing body of evidence suggests that e-cigarettes
can be an effective tool in helping smokers to quit smoking
[3–6]. E-cigarettes have become the most common quitting
aid for smokers in England, a finding supported by recent
data, suggesting that 38.2% of smokers in the last quarter
of 2017 reported using an e-cigarette in their recent quit
attempt compared with 18% using nicotine replacement
therapy (NRT) and 2.8% using Varenicline [3]. Studies
* Grant O’Connell
grant.oconnell@uk.imptob.com
* Tanvir Walele
Tanvir.Walele@fontemventures.com
1 Imperial Brands plc, 121 Winterstoke Road,
BristolBS32LL, UK
2 Celerion Inc., 621 Rose Street, Lincoln, NE68502, USA

Internal and Emergency Medicine
1 3
investigating abstinence rates have found that e-cigarettes
are helpful in enabling smokers to switch and subsequently
remain smoke free. For example, a 2016 report estimated
that 2.5% of smokers in England who used an e-cigarette
in their quit attempt (22,000 people) succeeded where they
would have failed if they had used nothing or a licensed
nicotine product purchased over the counter [7]. An analy-
sis of the data from the Eurobarometer 429 cross-sectional
survey, performed in a representative sample of the Euro-
pean Union 28 Member States in 2014, found that smoking
cessation with daily use of e-cigarettes was over 47% [8].
A recent study by Manzoli and colleagues followed up 236
e-cigarette users (all of whom were ex-smokers), 491 smok-
ers, and 232 dual users for 12months. They reported that
61.9% of the vapers were still abstinent from tobacco smok-
ing after 12months, compared with just 20.6% of the smok-
ers and 22.0% of the dual users, suggesting that e-cigarettes
can be effective in helping smokers abstain [9]. Research
undertaken by Polosa and colleagues has also shown that the
provision of e-cigarettes to smokers that have expressed no
prior commitment to stopping smoking is associated with a
significant reduction in smoking prevalence [10].
While there is a growing consensus that e-cigarettes
are substantially less harmful than smoking and have the
potential to generate substantial public health benefits at a
population level if significant numbers of smokers switch
from smoking to e-cigarette use [2, 3, 11, 12]; at this time,
only minority of smokers have fully switched to vaping.
For example, in the UK, there are an estimated 7.4 mil-
lion adults who continue to smoke [13]. Whilst inaccurate
beliefs on the relative harmfulness of e-cigarettes may be
deterring many smokers from even trying an e-cigarette [3],
it also suggests that currently available e-cigarettes do not
provide smokers with the sensory experience they require
from their conventional cigarettes [14]. Given the US Food
and Drug Administration (FDA) have highlighted the role of
nicotine in tobacco products, we hypothesise that the nico-
tine delivery profile of e-cigarettes may play a major role in
consumer-reported satisfaction [15].
Adapting the speed of nicotine delivery from e-ciga-
rettes may assist smokers in fully switching [16]. Nico-
tine replacement therapies (NRT) such as nicotine gums,
patches and inhalators, deliver nicotine much more slowly
and at lower doses than conventional cigarettes [3, 15, 17].
In addition to the absence of the behavioural and sensorial
aspects of the smoking experience using such products,
this may explain the limited success rate of NRT in smok-
ing cessation. Smoking abstinence using NRTs is report-
edly less than 7% after 12months [17]. There have been
number of attempts to develop an inhaled product which
would deliver nicotine through the lung and mimic the
physiological response from smoking. However, many of
them produced intolerable aversive reactions or delivered
an ineffective dose of nicotine [18]. By contrast, as e-cig-
arettes have evolved through several technical innovations,
their nicotine delivery has also improved, although it has
been shown to vary considerably across e-cigarette prod-
ucts [19–21]. Under the same puffing regime, experienced
e-cigarette users can achieve greater increases in blood
nicotine levels than naïve users, albeit at a much slower
rate than achieved by smoking a conventional cigarette
[20, 22]. E-cigarette nicotine intake and delivery have also
been shown to be related to, and influenced by, user puff-
ing topographies [1, 2, 23, 24], which differ significantly
from puffing behaviours associated with smoking [25,
26]. When focussing on experienced e-cigarette users, it
has been shown that comparable or higher blood nicotine
levels can be obtained compared to smoking [27, 28]. A
recent pharmacokinetic study also found that similar doses
and speed of nicotine delivery to conventional cigarettes
can be achieved among users of more modern advanced
tank e-cigarette devices [29].
The form of nicotine ordinarily used in e-liquids is termed
as ‘freebase’ nicotine. Freebase nicotine is volatile. As a
result, when an e-cigarette aerosol is inhaled by a user, the
nicotine is more likely to off-gas from the aerosol droplets
and deposit in the mouth/upper respiratory tract, where it is
absorbed into the blood. Absorption in the oral cavity/upper
respiratory tract is slower than that with conventional ciga-
rette with pharmacokinetic studies indicating a profile which
more closely resembles NRT than a conventional cigarette
[18]. The need for more effective and appealing e-cigarette
products to provide satisfying alternatives to smoking has
led to the recent development and marketing of e-liquids
containing ‘nicotine salts’. Nicotine salts are formed by the
reaction of nicotine with a suitable acid and are less volatile
than freebase nicotine [15]. As a result, a greater fraction of
the nicotine in the salt form would be expected to remain in
inhaled aerosol droplets until the aerosol reaches the alveoli
for pulmonary absorption. For pulmonary absorption, once
deposited, nicotine salts must first dissociate into freebase
and acid, to enable the non-polar, lipid-soluble freebase
nicotine to gain cellular entry at the alveoli [15]. If nicotine
salts can more closely replicate cigarette-like nicotine deliv-
ery in the lung, they should enable switching to e-cigarettes,
therefore helping to further realise the harm reduction poten-
tial of these products.
Currently, there are limited data in the published litera-
ture available on the pharmacokinetic profiles of e-cigarettes
containing nicotine salts. Here we performed a randomised,
open-label, six-period cross-over clinical study to evaluate
the nicotine uptake from two e-cigarette device platforms
with varying concentrations of nicotine lactate (nicotine salt)
or freebase nicotine e-liquids relative to conventional ciga-
rettes in US adult smokers. In addition, subjective effects
and tolerability of the tested products were also assessed.

Internal and Emergency Medicine
1 3
Methods
Study design
This randomised, open-label, six-period crossover study
(ClinicalTrials.gov; NCT03822546) was approved by the
Institutional Review Board of Chesapeake Research Review
(Maryland, USA) and was conducted in accordance with the
International Conference on Harmonisation (ICH) Harmo-
nised Tripartite Guideline for Good Clinical Practice (GCP)
and the Declaration of Helsinki. Up to 15 adult subjects (at
least six subjects of each sex) participated in this study which
was performed at a single clinical site (Celerion, Nebraska,
USA) in a confined setting over 6days in April 2018. All sub-
jects provided written informed consent prior to the study start.
Participants
Fifteen healthy American smokers aged 21–65years were
eligible for the study if they had smoked ≥ 10 manufactured
cigarettes (no restrictions on brand type) per day for at least
the last year. Women of child-bearing potential were eligible
only if they were using an accepted method of contraception.
All subjects had an expired carbon monoxide level of > 10ppm
at screening and tested positive for urinary cotinine (≥ 500ng/
mL). Subjects could try each product after check-in on Day 1
to ensure that they would be willing to use the products during
the pharmacokinetic evaluations. In total, subjects abstained
from using any tobacco or nicotine-containing product for at
least 18h prior to use on Day 1 (conventional cigarettes), and
thereafter were provided products at 24-h intervals.
Participants were excluded if they had a known or suspected
hypersensitivity to any component of the e-liquid formula-
tions; were taking or receiving prescription smoking cessa-
tion medicines; were willing or considering to stop smoking;
had a history or presence of clinically significant pulmonary,
cardiovascular, renal, hepatic, neurological, haematological,
endocrine, oncological, immunological or psychiatric condi-
tion that could place them at risk or interfere with the inter-
pretation of the study data; were a self-reported ‘puffer’, i.e.,
smokers who draw smoke into their mouth and throat but do
not inhale; or had a body mass index (BMI) of less than 18kg/
m2 or greater than 40kg/m2. Women who were breastfeeding
were excluded from the study.
No subjects reported previous e-cigarette use prior to
screening for the study and, thus, are considered naïve users.
Investigational products
The five e-cigarette products tested were (1) myblu pod-system
containing 25-mg nicotine (‘freebase’) tobacco flavour; (2)
myblu pod-system containing 16-mg nicotine lactate tobacco
flavour; (3) myblu pod-system containing 25-mg nicotine lac-
tate tobacco flavour; (4) myblu pod-system containing 40-mg
nicotine lactate tobacco flavour; and (5) blu PRO open system
containing 48-mg nicotine lactate tobacco flavour. The refer-
ence cigarettes, provided by the subjects, were their preferred
brand of commercially available conventional cigarette.
The e-cigarette products assessed in this study were
obtained from the US market and are manufactured by Fon-
tem Ventures B.V. (The Netherlands). The myblu device is
a rechargeable, closed pod-system e-cigarette, consisting
of two segments. A rechargeable battery section (battery
capacity, 350 mAh) and a replaceable e-liquid containing
pod (volume, 1.5mL; coil resistance, 1.3 Ω). The myblu
device delivers on average 7–8mg of aerosol per puff under
machine vaping conditions [30]. The blu PRO device is a
rechargeable, open-system e-cigarette, consisting of two
segments. A rechargeable battery section (battery capacity,
1100 mAh) and a refillable clearomiser (volume, 2.0mL;
coil resistance, 1.8 Ω). The blu PRO device delivers on aver-
age 2–3mg of aerosol per puff.
Procedure
Subjects visited the study site for a screening visit within
28days prior to baseline Day 1. Screening evaluations
included physical examination, vital signs, ECG, clinical
laboratory tests (clinical chemistry, haematology, urinaly-
sis, and serology), urine drug, cotinine, and alcohol screen,
and serum pregnancy tests for females only. On Day 1,
subjects completed a trial of all investigational products
and completed the Fagerström Test for Cigarette Depend-
ence (FTCD). On Days 1–6, after overnight smoking and
nicotine abstinence, participants used the assigned product
under controlled conditions according to their randomisa-
tion sequence. On Day 1, all participants smoked a single
preferred brand of conventional cigarette (not randomised)
with puffs taken at 30-s intervals. On each of Days 2–6,
participants received their randomised assigned e-cigarette
with a fully charged battery and fresh pre-filled pod (myblu)
or clearomiser (blu PRO) and used the product for 10 inhala-
tions every 30s for 3s in duration. All product use sessions
were directly monitored by the clinic staff, who indicated to
the subjects when to start and stop puffing. All e-cigarette
products were weighed before and after use to determine the
quantity of e-liquid consumed.
Study assessments
Pharmacokinetic analysis
Plasma nicotine pharmacokinetic assessment was the pri-
mary outcome measure for this study. On each study day
(Days 1–6), 4mL of whole blood was collected 5min prior

Internal and Emergency Medicine
1 3
to and at 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, and 30min fol-
lowing the start of product use. Plasma was separated by
centrifugation within 60min of collection, aliquoted and
stored at − 20°C. The determination of plasma nicotine con-
centrations was carried out using a validated LC–MS/MS
method, over a calibration range spanning from the lower
limit of quantification of 0.200–25.0ng/mL.
The pharmacokinetic parameters determined were the
mean maximum plasma nicotine concentration (Cmax), the
median time to maximum plasma nicotine concentration
(Tmax), and the mean area under the plasma nicotine con-
centration–time curve, from time 0 to 30min (AUC
0–30).
Pharmacokinetic analyses were performed using Phoe-
nix™ WinNonlin® Version 7.0.
Subjective eects
To assess the impact of the investigational products on desire
to smoke, their effects on aspects of nicotine satisfaction
and other subjective measures, responses were elicited on a
Likert-type scale with responses ranging from 1 (not at all)
to 7 (extremely). The following questions were compiled by
the clinical research organisation and were based on previ-
ous questionnaires designed to assess the effects of tobacco
product use [31, 32]: Did it make you dizzy? Did it make
you nauseous? Did you enjoy it? Did it relieve the urge to
smoke? Was it enough nicotine? Was it too much nicotine?
This assessment was made 20min after the start of product
use.
Safety andtolerability
Safety and tolerability were assessed by the study investiga-
tor. The incidence and nature of any adverse events (AEs)
and concomitant medications throughout the study were
recorded by assessment of reported events, physical exami-
nation, monitoring of vital signs (respiratory rate, heart
rate, blood pressure, ECG, and temperature) and clinical
biochemistry tests (clinical chemistry, haematology and
urinalysis).
Statistical analyses
Statistical summarizations were performed using SAS® Ver-
sion 9.3.
The sample size was determined adequate for nicotine
bioavailability comparisons and was selected based on simi-
lar pharmacokinetic studies on e-cigarette products [20–22,
31–34].
Participants were included in the pharmacokinetic pop-
ulation if they completed use of the tested investigational
product and evaluable data for the specified endpoints were
obtained. Baseline adjustments were performed. For the
subjective effects, descriptive statistics were calculated.
For AEs, investigational product use-emergent AEs are sum-
marised; an investigational product use-emergent AE was
defined as an AE that started or worsened at the time of, or
after, the first investigational product is used.
To determine whether pharmacokinetic parameters fol-
lowing use of the e-cigarette products were significantly
different from those of the conventional cigarette, a multi-
ple test comparison with a P value adjustment based on the
Westfall–Young approach was used. If the P value was less
than 0.05, the difference was considered to be statistically
significant where *P < 0.05, **P < 0.01 and ***P < 0.001.
Individual participants’ subjective scores to each investi-
gational product type were analysed by means of a non-para-
metric randomised block analysis of variance Friedman test.
Where a significant difference was observed (*P < 0.05),
post hoc comparisons were performed using a Nemenyi
test, with differences considered as statistically significant
for *P < 0.05.
Results
Study population
Fifteen subjects were enrolled to test each investigational
product. There was one non-completer for the myblu 25mg
(freebase) and blu PRO 48mg (nicotine lactate) and two
for the myblu 25mg (nicotine lactate) which did not result
from product-related AEs. The baseline characteristics of
the subjects are summarised in Table1. No subjects reported
previous e-cigarette use prior to screening for the study.
Study product use
The mean number of puffs taken during each product use
session and the change in e-cigarette mass are reported
in Table2. Ten puffs were taken from each of the myblu
products containing nicotine lactate during each use ses-
sion, while one puff from the myblu 25mg (freebase), blu
PRO 48mg (nicotine lactate), and conventional cigarette
was missed by two subjects. All conventional cigarettes were
consumed in 9 or 10 puffs. Mean product mass changes from
pre- to post-use was greatest for the myblu 16-mg (nicotine
lactate) product, followed by the myblu 40mg (nicotine lac-
tate), myblu 25mg (nicotine lactate), myblu 25mg (free-
base), and blu PRO 48mg (nicotine lactate), respectively.
Pharmacokinetic analysis
The mean plasma nicotine concentration profiles of the con-
ventional cigarettes and the investigational e-cigarette prod-
ucts are shown in Fig.1 and the pharmacokinetic parameters

Internal and Emergency Medicine
1 3
for each product are reported in Table3. The myblu 40mg
(nicotine lactate) product had the closest set of pharmacoki-
netic parameters to that of the conventional cigarette.
All e-cigarette products had a median Tmax that was in the
range of the conventional cigarette indicating aerosol deposi-
tion in the deep lung facilitating rapid nicotine absorption
from all tested e-cigarettes.
The Cmax for all the e-cigarette products was significantly
lower (P < 0.05) than that of the conventional cigarette,
except for the myblu 40-mg (nicotine lactate) product which
was not significantly different. An increase in the nicotine
lactate concentration in the myblu device also resulted in an
increased Cmax, with a trend toward dose proportionality.
Of note, the Cmax was significantly higher (P < 0.05) for the
myblu 40-mg (nicotine lactate) product than the blu PRO
48-mg (nicotine lactate) open-system device which is likely
to be reflective of the technological improvements of the
newer myblu device.
For all e-cigarette products, the extent of nicotine absorp-
tion (AUC
0–30) was significantly less (P < 0.05) than that of
the conventional cigarette, except for the myblu 40-mg (nico-
tine lactate) product which was not significantly different.
With increasing nicotine lactate concentrations in the myblu
device, the AUC
0–30 increased, with a trend toward dose pro-
portionality. The blu 48-mg (nicotine lactate) product had
an AUC
0–30 significantly less than that of the myblu 40-mg
(nicotine lactate) product again indicating the improved
aerosol generation properties and nicotine delivery of the
myblu device vs the blu PRO device, which uses an older
aerosol generation technology.
Subjective eects
Subjective effect scores are reported in Table4. Subjective
scores were numerically highest for all questions after use of
the conventional cigarette followed by the myblu 40-mg (nic-
otine lactate) product. For three questions (Did it make you
dizzy? Did it relieve the urge to smoke? and Was it enough
nicotine?), a significant difference was observed between the
six investigational products (P < 0.05). In general, a rapid
absorption of nicotine with a higher Cmax appears to produce
greater relief in desire to smoke which may be important for
facilitating smoker switching and preventing relapse. The
other subjective measures appear to be numerically compa-
rable and not significantly different across all formulations
irrespective of nicotine delivery, indicating that in addition
to nicotine, other behavioural and sensorial elements that
e-cigarettes provide play a role in satisfaction.
Safety andtolerability
There were no serious adverse events reported during the
study. Product-use AEs were infrequent with four subjects
reporting 10 AEs in this study, none of which led to discon-
tinuation. Vessel puncture site pain was the most frequently
reported AE, experienced by two subjects. All remaining
Table 1 Demographic and baseline characteristics of the pharmacoki-
netic population
BMI body mass index; FTCD Fagerström Test for Cigarette Depend-
ence Questionnaire; SD standard deviation
a 15 enrolled, 1 participant did not use myblu 25 mg (freebase) and
blu PRO 48mg (nicotine lactate) and 2 participants did not use myblu
25mg (nicotine lactate)
Variable Characteristics
Number of subjects, n15a
Smoker type 10 ‘full flavour’
cigarettes; 5 ‘light’
cigarettes
1 menthol
14 non-menthol
Age (years)
Mean (SD) 42.3 (12.41)
Range 24–62
Sex, n (%)
Male 9 (60%)
Female 6 (40%)
BMI (kg/m2)
Mean (SD) 28.137 (5.1412)
Range 20.20–39.49
FTCD (total score)
Mean (SD) 5.5
Range 3–9
Table 2 Summary of product use by investigational product type
All values are arithmetic mean and standard deviation (SD)
NA not applicable
Conven-
tional
cigarette
myblu 40mg (nico-
tine lactate)
myblu 25mg (nico-
tine lactate)
myblu 16mg (nico-
tine lactate)
blu PRO 48mg
(nicotine lactate)
myblu 25mg
(freebase)
Number of puffs 9.9 (0.35) 10.0 (0.00) 10.0 (0.00) 10.0 (0.00) 9.9 (0.27) 9.9 (0.27)
Product mass
change (g)
NA 0.04853 (0.022660) 0.04425 (0.018735) 0.06526 (0.028930) 0.01791 (0.013702) 0.04396 (0.019524)

Internal and Emergency Medicine
1 3
Fig. 1 Pharmacokinetic profiles:
mean plasma nicotine concen-
tration by investigational prod-
uct (linear scale) over 30 min
Table 3 Summary of pharmacokinetic parameters by investigational product type
All values are geometric mean and geometric coefficient of variation (CV%) unless stated otherwise
Cmax maximum plasma nicotine concentration; Tmax time to maximum nicotine concentration; AUC
0–30 area under the concentration–time curve
from time zero to the last quantifiable concentration (30min)
*Significant difference compared to conventional cigarette (**P < 0.01 and ***P < 0.001)
† Significant difference between myblu 40mg (nicotine lactate) and blu PRO 48mg (nicotine lactate) (†P < 0.05; ††P < 0.01)
Conventional
cigarette
myblu 40mg
(nicotine
lactate)
myblu 25mg
(nicotine lactate)
myblu 16mg (nico-
tine lactate)
blu PRO 48mg
(nicotine lactate)
myblu 25mg
(freebase)
Cmax, ng/mL 17.81 (49.6) 10.27 (83.6) 7.58 (80.6)** 6.51 (76.5)*** 4.85 (108.3)***, † 5.048 (49.9)***
Tmax, median
(range), min
8.05 (5.00–15.13) 7.9 (1.97–15.0) 6.03 (4.58–16.77) 6.967 (3.98–15.05) 6.908 (2.35–15.03) 8.034 (2.28–15.10)
AUC
0–30, ng*min/
mL
324.9 (35.8) 190.7 (71.8) 125.2 (53.4)*** 118.5 (60.8)*** 84.84 (89.8)***, †† 98.99 (35.8)***
Table 4 Summary of subjective evaluations of each investigational product type
Scale: 1, not at all; 2, very little; 3, a little; 4, modestly; 5, a lot; 6, quite a lot; 7, extremely
All values are mean and standard deviation (SD)
* Significant difference between the six investigational products (*P < 0.05)
Conventional
cigarette
myblu 40mg
(nicotine lactate)
myblu 25mg
(nicotine lactate)
myblu 16mg
(nicotine lactate)
blu PRO 48mg
(nicotine lactate)
myblu 25mg
(freebase)
Did it make you dizzy?* 3.7 (1.80) 2.8 (1.78) 2.1 (1.32) 1.5 (0.74) 1.7 (0.99) 1.9 (1.73)
Did it make you nauseous? 1.9 (1.44) 1.4 (0.91) 1.2 (0.44) 1.1 (0.26) 1.4 (0.84) 1.3 (0.83)
Did you enjoy it? 4.9 (1.44) 4.0 (1.36) 3.5 (1.98) 3.5 (1.46) 3.2 (1.81) 3.5 (1.87)
Did it relieve the urge to smoke?* 5.5 (1.60) 4.1 (1.79) 3.5 (1.98) 3.3 (1.91) 3.1 (2.11) 3.6 (2.10)
Was it enough nicotine?* 5.4 (1.55) 4.3 (1.79) 3.1 (1.93) 3.3 (1.99) 3.2 (2.08) 4.0 (1.96)
Was it too much nicotine? 2.4 (1.55) 2.2 (1.66) 1.5 (0.97) 1.7 (1.11) 1.4 (0.63) 2.5 (2.21)

Internal and Emergency Medicine
1 3
AEs were experienced by one subject each. All AEs were
mild in severity, apart from moderate insomnia with the
blu PRO 48mg (nicotine lactate). The principal investiga-
tor considered one AE of headache with the myblu 25mg
(freebase) to be possibly related to study product and the
remaining nine events unlikely or unrelated.
The use of the e-cigarette products under the study con-
ditions appeared to be well tolerated by the healthy adult
smokers in this study.
Discussion
This study provides new insights into e-cigarette products
that contain nicotine lactate when used by adult smokers
under controlled conditions. The data indicate that nicotine
in lactate salt formulation is rapidly delivered into the sys-
temic circulation following inhalation using nicotine lactate
e-cigarette products with plasma pharmacokinetic profiles
consistent with pulmonary absorption; however, with nico-
tine doses less than that of a conventional cigarette. Com-
pared to conventional cigarettes, exposure to nicotine was
41% lower following use of myblu 40mg (nicotine lactate),
60% lower following use of myblu 25mg (nicotine lactate),
63% lower following use of myblu 16mg (nicotine lactate),
and 70% lower following use of myblu 25mg (freebase).
The blu PRO 48-mg (nicotine lactate) product delivered
approximately 73% less nicotine compared to conventional
cigarettes.
As might be expected, variations in the concentration
of nicotine content of the e-liquid also had an impact on
nicotine delivery. Indeed, the pharmacokinetic profile of the
40-mg nicotine lactate e-cigarette product was approach-
ing that of a conventional cigarette; whereas, the 16-mg
comparator was significantly different. The subjective data
also show that the 40-mg nicotine lactate product reduced
the desire to smoke numerically more than the 16-mg nico-
tine lactate product; this may be consistent with an efficient
transfer of more nicotine to the lungs and a rapid rise of
nicotine absorption in the plasma. These initial findings sug-
gest that e-cigarettes with a higher concentration of nicotine
in nicotine lactate form may be more effective and more
appealing products for adult smokers switching from ciga-
rettes to vapour products. This is in line with public health
recommendations in the UK and elsewhere, e.g. [3, 12, 35].
From smoking a conventional cigarette, a plasma nico-
tine concentration of around 4ng/mL has been reported to
occupy up to 90% of available α4β2* nicotinic acetylcholine
receptors in the brain and significantly reducing desire to
smoke [36]. By contrast, following use of a licensed nicotine
inhaler, a peak receptor occupancy of 60% is only reached
after 3h which was insufficient to reduce desire to smoke
[37]. Thus, it appears that a shorter Tmax is important to
activate most nicotine receptors and provide smoker satisfac-
tion from alternative products. In our study, the Tmax values
for all e-cigarettes were in a range which is comparable to
published conventional cigarette data [38]. A study is under-
way to assess smoking reduction and switch rates associ-
ated with nicotine lactate e-cigarette adlibitum use in the
real-world with medicinal nicotine replacement product and
freebase e-cigarette comparators.
The European Union Tobacco Products Directive
(EUTPD) mandates that the maximum nicotine content of
an e-liquid cannot exceed 20mg/mL. Recent research has
shown that the use of lower nicotine concentration e-liq-
uids may be associated with ‘compensatory behaviour’ as
e-cigarette users puff more deeply, more frequently and for
longer to obtain a level of nicotine that reduces desire to
smoke [39]. In the present study, the myblu 40-mg nico-
tine lactate product had the closest nicotine uptake profile
to the conventional cigarette with the greatest relief in desire
to smoke. However, this product would not be permitted
in the European Union. Both Public Health England and
the Royal College of Physicians have stated that the cap on
nicotine concentrations imposed by the EUTPD may limit
the effectiveness of e-cigarettes as a smoking substitute,
particularly for heavier smokers [1, 2]. Based on our initial
data presented here, and other research insights [40], the
EUTPD nicotine concentration limit should be reviewed in
line with the scientific literature to ensure that adult smokers
have ready access to better alternatives that reduce desire to
smoke. Higher nicotine strength liquids with nicotine lactate
formulations and suitable flavour options that can be mar-
keted to smokers may maximise the public health potential
of e-cigarettes.
This was a small, short-duration study that was not
designed to fully evaluate safety. However, reports of AEs
were recorded, and the study was conducted to GCP. Use
of the nicotine lactate e-cigarettes was well tolerated by the
participants with no severe or serious AEs and no partici-
pants discontinued the study owing to an AE.
The main limitation of this study is that the e-cigarette
puff profile was fixed (use was not adlibitum) to obtain
clear pharmacokinetic profiles and blood sampling was
collected for only 30min. A more robust pharmacokinetic
assessment is planned in future studies. It is likely that
smokers using the e-cigarette devices in the ‘real world’
would change their behaviour to adapt to the new products
and own preference. To assess the amount of nicotine and
smoker satisfaction that nicotine lactate e-cigarettes pro-
vide under real-world conditions, it would be beneficial
to conduct a long-term study that allows subjects to adapt
their behaviour to product use. Another limitation is that
study participants were not experienced e-cigarette users.
However, prior to study start, subjects could use each of
the products, although their preferences on the products

Internal and Emergency Medicine
1 3
ahead of the study start were not known. This may have
influenced the reporting of subjective effects. The e-ciga-
rette products may not have been used in an optimal way
or in the same way they would have been used had the
participants been familiar with the product; a longer famil-
iarisation training period would be beneficial in future
studies. Furthermore, only tobacco-flavoured e-cigarettes
were assessed in this study; had the participants the oppor-
tunity to vary the flavour it may have influenced product
use and satisfaction. In the present study, only nicotine
lactate salt formulations were assessed; further research is
also warranted to determine the pharmacokinetic profiles
and efficacy of other nicotine salt formulations.
Conclusion
In summary, the results of this study indicate that the use
of nicotine lactate in e-cigarettes has promise as an effec-
tive form of nicotine replacement. The pharmacokinetic
and subjective data demonstrate that nicotine lactate can
be used to deliver nicotine via the pulmonary route for
increased speed of absorption, albeit with a maximum nic-
otine level that did not exceed the conventional cigarette,
coupled with acceptable subjective satisfaction and relief
of desire to smoke. Further studies are warranted to fully
assess the efficacy of nicotine lactate in aiding smokers to
fully switch to e-cigarettes in the real-world, as well as the
research on the role of flavours and other innovations that
can maximise the public health potential of alternatives to
cigarettes for adult smokers.
Acknowledgements The authors thank Celerion who conducted the
study and analysed the data.
Funding This study was supported by Imperial Brands plc. Fontem
Ventures B.V., the manufacturer of the investigational e-cigarettes used
in this study, is a wholly owned subsidiary of Imperial Brands plc.
Compliance with ethical standards
Conflict of interest GOC, JDP, CP, JT, TV and TW are full time em-
ployees of the Imperial Brands Group. Celerion has received funding
from several e-cigarette/tobacco manufacturers to conduct pharma-
cokinetic/pharmacodynamic studies of their products with smokers
and vapers, as well as biomarker studies on smokers who switch to
vaping.
Ethics approval The study is registered at ClinicalTrials.gov
(NCT03822546) and a favourable ethical opinion of this study was
given by the Institutional Review Board of Chesapeake Research
Review (Maryland, USA).
Informed consent Participants were presented with an Informed Con-
sent Form and gave written consent to participate at the start of the
study.
Open Access This article is distributed under the terms of the Crea-
tive Commons Attribution 4.0 International License (http://creat iveco
mmons .org/licen ses/by/4.0/), which permits unrestricted use, distribu-
tion, and reproduction in any medium, provided you give appropriate
credit to the original author(s) and the source, provide a link to the
Creative Commons license, and indicate if changes were made.
References
1. McNeill A, Brose LS, Calder R, Hitchman SC, Hajek P, McRob-
bie H (2015) E-cigarettes: an evidence update (Public Health Eng-
land 2015 report). Public Health England
2. Royal College of Physicians (2016) Nicotine without smoke:
tobacco harm reduction. https ://www.rcplo ndon.ac.uk/proje
cts/outpu ts/nicot ine-witho ut-smoke -tobac co-harm-reduc tion-0.
Accessed Dec 2018
3. McNeill A, Brose LS, Calder R, Bauld L, Robson D (2018) Evi-
dence review of e-cigarettes and heated tobacco products 2018.
A report commissioned by Public Health England. London
4. McRobbie H, Bullen C, Hartmann-Boyce J, Hajek P (2014) Elec-
tronic cigarettes for smoking cessation and reduction. Cochrane
Database Syst Rev 12:CD010216. https ://doi.org/10.1002/14651
858.cd010 216.pub2
5. Hartmann-Boyce J, McRobbie H, Bullen C, Begh R, Stead
LF, Hajek P (2016) Electronic cigarettes for smoking cessa-
tion. Cochrane Database Syst Rev 9:Cd010216. https ://doi.
org/10.1002/14651 858.cd010 216.pub3
6. Hajek P, Corbin L, Ladmore D, Spearing E (2015) Adding e-cig-
arettes to specialist stop-smoking treatment: city of London pilot
project. J Addict Res Ther 6:244
7. West R, Shahab L, Brown J (2016) Estimating the population
impact of e-cigarettes on smoking cessation in England. Addiction
(Abingdon, England) 111(6):1118–1119. https ://doi.org/10.1111/
add.13343
8. Farsalinos KE, Poulas K, Voudris V, Le Houezec J (2017) Preva-
lence and correlates of current daily use of electronic cigarettes in
the European Union: analysis of the 2014 Eurobarometer survey.
Intern Emerg Med 12(6):757–763. https ://doi.org/10.1007/s1173
9-017-1643-7
9. Manzoli L, Flacco ME, Fiore M, La Vecchia C, Marzuillo C,
Gualano MR, Liguori G, Cicolini G, Capasso L, D’Amario C,
Boccia S, Siliquini R, Ricciardi W, Villari P (2015) Electronic
cigarettes efficacy and safety at 12 months: cohort study. PLoS
One 10(6):e0129443. https ://doi.org/10.1371/journ al.pone.01294
43
10. Polosa R, Caponnetto P, Maglia M, Morjaria JB, Russo C (2014)
Success rates with nicotine personal vaporizers: a prospective
6-month pilot study of smokers not intending to quit. BMC Public
Health 14:1159. https ://doi.org/10.1186/1471-2458-14-1159
11. National Academies of Science, Engineering and Medicine (2018)
Public health consequences of e-cigarettes. http://natio nalac ademi
es.org/hmd/Repor ts/2018/publi c-healt h-conse quenc es-of-eciga
rette s.aspx. Accessed Dec 2018
12. US Food and Drug Administration (2017) FDA announces com-
prehensive regulatory plan to shift trajectory of tobacco-related
disease, death. https ://www.fda.gov/newse vents /newsr oom/press
annou nceme nts/ucm56 8923.htm. Accessed Dec 2018
13. Office for National Statistics (2018) Adult smoking habits in the
UK: 2017. https ://www.ons.gov.uk/peopl ep opu la tio na ndc om mun
ity/healt hands ocial care/healt handl ifeex pecta ncies /bulle tins/adult
smoki nghab itsin great brita in/2017. Accessed July 2018
14. Khoudigian S, Devji T, Lytvyn L, Campbell K, Hopkins R,
O’Reilly D (2016) The efficacy and short-term effects of electronic

Internal and Emergency Medicine
1 3
cigarettes as a method for smoking cessation: a systematic review
and a meta-analysis. Int J Public Health 61(2):257–267. https ://
doi.org/10.1007/s0003 8-016-0786-z
15. Caldwell B, Sumner W, Crane J (2012) A systematic review of
nicotine by inhalation: is there a role for the inhaled route? Nico-
tine Tob Res 14(10):1127–1139. https ://doi.org/10.1093/ntr/nts00
9
16. Schroeder MJ, Hoffman AC (2014) Electronic cigarettes and nico-
tine clinical pharmacology. Tob Control 23(Suppl 2):ii30–ii35.
https ://doi.org/10.1136/tobac cocon trol-2013-05146 9
17. Konstantinos F (2017) Electronic cigarettes: an aid in smoking
cessation, or a new health hazard? Ther Adv Respir Dis. https ://
doi.org/10.1177/17534 65817 74496 0
18. Cipolla D, Gonda I (2015) Inhaled nicotine replacement therapy.
Asian J Pharm Sci 10(6):472–480. https ://doi.org/10.1016/j.
ajps.2015.07.004
19. Glasser AM, Collins L, Pearson JL, Abudayyeh H, Niaura RS,
Abrams DB, Villanti AC (2016) Overview of electronic nicotine
delivery systems: a systematic review. Am J Prev Med. https ://doi.
org/10.1016/j.amepr e.2016.10.036
20. Hajek P, Przulj D, Phillips A, Anderson R, McRobbie H (2017)
Nicotine delivery to users from cigarettes and from different types
of e-cigarettes. Psychopharmacology. https ://doi.org/10.1007/
s0021 3-016-4512-6
21. Dawkins L, Corcoran O (2014) Acute electronic cigarette use:
nicotine delivery and subjective effects in regular users. Psychop-
harmacology 231(2):401–407. https ://doi.org/10.1007/s0021
3-013-3249-8
22. Farsalinos KE, Spyrou A, Tsimopoulou K, Stefopoulos C,
Romagna G, Voudris V (2014) Nicotine absorption from elec-
tronic cigarette use: comparison between first and new-generation
devices. Sci Rep 4:4133. https ://doi.org/10.1038/srep0 4133
23. Dawkins LE, Kimber CF, Doig M, Feyerabend C, Corcoran O
(2016) Self-titration by experienced e-cigarette users: blood nico-
tine delivery and subjective effects. Psychopharmacology. https ://
doi.org/10.1007/s0021 3-016-4338-2
24. St Helen G, Ross KC, Dempsey DA, Havel CM, Jacob P 3rd,
Benowitz NL (2016) Nicotine delivery and vaping behavior dur-
ing adlibitum e-cigarette access. Tob Regul Sci 2(4):363–376.
https ://doi.org/10.18001 /trs.2.4.8
25. Farsalinos KE, Romagna G, Tsiapras D, Kyrzopoulos S, Voudris V
(2013) Evaluation of electronic cigarette use (vaping) topography
and estimation of liquid consumption: implications for research
protocol standards definition and for public health authorities’
regulation. Int J Environ Res Public Health 10(6):2500–2514.
https ://doi.org/10.3390/ijerp h1006 2500
26. Behar RZ, Hua M, Talbot P (2015) Puffing topography
and nicotine intake of electronic cigarette users. PLoS One
10(2):e0117222. https ://doi.org/10.1371/journ al.pone.01172 22
27. Ramoa CP, Hiler MM, Spindle TR, Lopez AA, Karaoghlanian
N, Lipato T, Breland AB, Shihadeh A, Eissenberg T (2015)
Electronic cigarette nicotine delivery can exceed that of com-
bustible cigarettes: a preliminary report. Tob Control. https ://doi.
org/10.1136/tobac cocon trol-2015-05244 7
28. St Helen G, Havel C, Dempsey D, Jacob P 3rd, Benowitz NL
(2015) Nicotine delivery, retention, and pharmacokinetics from
various electronic cigarettes. Addiction (Abingdon, England).
https ://doi.org/10.1111/add.13183
29. Wagener TL, Floyd EL, Stepanov I, Driskill LM, Frank SG, Meier
E, Leavens EL, Tackett AP, Molina N, Queimado L (2016) Have
combustible cigarettes met their match? The nicotine delivery
profiles and harmful constituent exposures of second-generation
and third-generation electronic cigarette users. Tob Control. https
://doi.org/10.1136/tobac cocon trol-2016-05304 1
30. CORESTA (2015) Routine analytical machine for e-cigarette aero-
sol generation and collection – definitions and standards. https ://
www.cores ta.org/sites /defau lt/files /techn ical_docum ents/main/
CRM_81.pdf. Accessed Jan 2019
31. Bullen C, McRobbie H, Thornley S, Glover M, Lin R, Laug-
esen M (2010) Effect of an electronic nicotine delivery device
(e cigarette) on desire to smoke and withdrawal, user preferences
and nicotine delivery: randomised cross-over trial. Tob Control
19(2):98–103. https ://doi.org/10.1136/tc.2009.03156 7
32. Walele T, Sharma G, Savioz R, Martin C, Williams J (2016) A
randomised, crossover study on an electronic vapour product, a
nicotine inhalator and a conventional cigarette. Part A: pharma-
cokinetics. Regul Toxicol Pharmacol RTP 74:187–192. https ://
doi.org/10.1016/j.yrtph .2015.12.003
33. Teichert A, Brossard P, Felber Medlin L, Sandalic L, Franzon M,
Wynne C, Laugesen M, Lüdicke F (2018) Evaluation of nicotine
pharmacokinetics and subjective effects following use of a novel
nicotine delivery system. Nicotine Tob Res 20(4):458–465. https
://doi.org/10.1093/ntr/ntx09 3
34. St Helen G, Dempsey DA, Havel CM, Jacob P III, Benowitz NL
(2017) Impact of e-liquid flavors on nicotine intake and phar-
macology of e-cigarettes. Drug Alcohol Depend. https ://doi.
org/10.1016/j.druga lcdep .2017.05.042
35. Government of Canada (2018) Vaping and quitting smoking. https
://www.canad a.ca/en/healt h-canad a/servi ces/smoki ng-tobac co/
vapin g/smoke rs.html. Accessed Jan 2019
36. Brody AL, Mandelkern MA, London ED, Olmstead RE, Farahi
J, Scheibal D, Jou J, Allen V, Tiongson E, Chefer SI, Koren AO,
Mukhin AG (2006) Cigarette smoking saturates brain alpha 4
beta 2 nicotinic acetylcholine receptors. Arch Gen Psychiatry
63(8):907–915. https ://doi.org/10.1001/archp syc.63.8.907
37. Esterlis I, Mitsis EM, Batis JC, Bois F, Picciotto MR, Stiklus SM,
Kloczynski T, Perry E, Seibyl JP, McKee S, Staley JK, Cosgrove
KP (2011) Brain β(2)*-nicotinic acetylcholine receptor occu-
pancy after use of a nicotine inhaler. Int J Neuropsychopharmacol
14(3):389–398. https ://doi.org/10.1017/S1461 14571 00012 27
38. Benowitz NL, Hukkanen J, Jacob P (2009) Nicotine chemistry,
metabolism, kinetics and biomarkers. Handb Exp Pharmacol
192:29–60. https ://doi.org/10.1007/978-3-540-69248 -5_2
39. Kośmider L, Kimber CF, Kurek J, Corcoran O, Dawkins L (2017)
Compensatory puffing with lower nicotine concentration e-liquids
increases carbonyl exposure in e-cigarette aerosols. Nicotine Tob
Res. https ://doi.org/10.1093/ntr/ntx16 2
40. House of Commons Science and Technology Committee (2018)
E-cigarettes seventh report of the session 2017–19. https ://publi
catio ns.parli ament .uk/pa/cm201 719/cmsel ect/cmsct ech/505/505.
pdf. Accessed Jan 2019
Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.