NCT02590393.

Study name	The role of nicotine and non‐nicotine alkaloids in e‐cigarette use and dependence
Methods	Randomized parallel‐assignment double‐blind trial Setting: Smoking research clinic, USA Recruitment: volunteers
Participants	Estimated enrolment: 375 Inclusion criteria: Have no known serious medical conditions Are 18‐65 years old Smoke an average of at least 10 cpd Have smoked at least 1 cumulative year Have an expired air CO reading of at least 10 ppm Are able to read and understand English Exclude if: multiple, related to baseline health status
Interventions	Switch to standard nicotine EC use for 8 weeks Switch to ECs with same nicotine but very low non‐nicotine alkaloid levels Switch to ECs with very low nicotine and non‐nicotine alkaloids
Outcomes	Primary: CO levels at 8 weeks Secondary: EC use EC solution use cigarette use, at 8 weeks
Starting date	May 2016
Contact information	Jed Rose
Notes	"This is not a smoking cessation study; people who smoke will not be asked to quit smoking, and e‐cigarettes will not be used as a medical device or therapy."