Abstract
Rationale
Self-titration is well documented in the tobacco literature. The extent to which e-cigarette users (vapers) self-titrate is unknown.
Objective
This study explored the effects of high and low nicotine strength liquid on puffing topography, nicotine delivery and subjective effects in experienced vapers.
Methods
Eleven experienced male vapers completed 60 min of ad libitum vaping under low (6 mg/mL) and high (24 mg/mL) nicotine liquid conditions in two separate sessions. Measurements included puffing topography (puff number, puff duration, volume of liquid consumed) and changes in plasma nicotine levels, craving, withdrawal symptoms, self-reported hit, satisfaction and adverse effects.
Results
Liquid consumption and puff number were higher and puff duration longer, in the low nicotine strength condition (all ps < 0.01). The mean difference in nicotine boost from baseline in the low condition was 8.59 (7.52) ng/mL, 16.99 (11.72) ng/mL and 22.03 (16.19) ng/mL at 10, 30 and 60 min, respectively. Corresponding values for the high condition were 33.77 (34.88) ng/mL, 35.48 (28.31) ng/mL and 43.57 (34.78) ng/mL (ps < 0.05). There were no statistically significant differences between conditions in self-reported craving, withdrawal symptoms, satisfaction, hit or adverse effects.
Conclusions
Vapers engaged in compensatory puffing with lower nicotine strength liquid, doubling their consumption. Whilst compensatory puffing was sufficient to reduce craving and withdrawal discomfort, self-titration was incomplete with significantly higher plasma nicotine levels in the high condition.
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Acknowledgments
This study forms part of a PhD research project and is funded by an ‘Excellence Studentship’ awarded to the second author from the University of East London (UEL). We also thank the participants for their time and participation in this research and the technical support staff at the School of Health, Sport and Bioscience: Mr Paul Boakes and Mr Rory Butterworth.
Details of contributors
LED and OC conceived the original idea for this study and designed the study with input from CK and MD. CK, LED and OC managed the running of the participant facing experiment; OC and CK were responsible for the plasma extraction and MD and CF conducted the biochemical analysis of blood and saliva samples. CK and LED analysed the data and wrote the first draft with edits from OC, MD and CF. All authors had full access to all of the data and collectively take responsibility for the integrity of the data and accuracy of the data analysis. All authors read and approved the final version of the manuscript. Study guarantor: UEL.
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The study received full ethical approval from the University of East London’s ethics committee (UREC_1415_40) and was conducted in accordance with the ethical standards outlined in the 1964 Declaration of Helsinki. All participants provided written informed consent to take part in the study and for the study to be written up for publication.
Funding
This study was fully funded by the University of East London PhD Excellence Studentship to CK.
Conflict of interest
We declare that we have received no support from any companies for this work and no non-financial conflicts of interest that would be considered relevant to this work. All authors have completed the conflict of interest disclosure form at http://static.springer.com/sgw/documents/1378102/application/pdf/213_Conflict+of+Interest+form-Mar2012.pdf (available on request from the corresponding author).
LED has previously conducted research for several independent electronic cigarette companies. These companies had no input into the design, conduct or write up of the projects. She has also acted as a consultant for the pharmaceutical industry and as an expert witness in a patent infringement case.
CK and OC declare no competing interests.
MD and CF have previously supported other research groups by the quantification of cotinine, 3-hydroxy cotinine and nicotine. These groups had no input into the design, conduct or write up of this project.
Role of the funding source
The funders (UEL) had no involvement in the study design, data collection, analysis or interpretation of data or in the writing of the manuscript or the decision to submit the article for publication.
The authors had sole responsibility for the study design, collection, analysis and interpretation of data and for the writing of the manuscript and decision to submit for publication.
All authors had full access to all of the data (including statistical reports and tables) in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
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I, LED the lead author, affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; no important aspects of the study have been omitted.
Data sharing statement
All participants gave informed consent for data sharing and full dataset will be available after publication of the manuscript on the UEL data repository.
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Dawkins, L.E., Kimber, C.F., Doig, M. et al. Self-titration by experienced e-cigarette users: blood nicotine delivery and subjective effects. Psychopharmacology 233, 2933–2941 (2016). https://doi.org/10.1007/s00213-016-4338-2
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DOI: https://doi.org/10.1007/s00213-016-4338-2