This is a crossover study that will examine use behaviors, chemical exposures, and biological effects of Standardized Research Electronic Cigarette (SREC) compared to usual brand e-cigarette use in natural or synthetic nicotine users.

OBJECTIVES:

I. To characterize nicotine delivery, systemic exposure and effects from SREC in comparison with usual to usual nicotine brand use.

II. To assess aspects of harm of SREC use compared to usual nicotine brand use.

OUTLINE:

Eligible participants will be assigned to one of two treatment conditions for the initial assessment which will take place in a hospital setting. The participant will then be assigned to the second condition within 2 weeks after the initial assessment which will also take place in a hospital setting to repeat the same procedures.

Inclusion Criteria:

• Healthy on the basis of medical history and limited physical examination-

  • Heart rate < 105 beats per minute (BPM)*.
  • Systolic Blood Pressure < 160 and > 90*.
  • Diastolic Blood Pressure < 100 and > 50*.
  • *considered out of range if both machine and manual readings are above/below these thresholds.
  • Body Mass Index <= 38.0.

• Current regular user of electronic cigarettes (EC)

  • EC device use at least 15 or more days in the past 30 days (with e- liquid >= 3mg/ml)
  • No restriction on flavor or type of e-cigarette used
  • Saliva cotinine >= 50 ng/ml and/or NicAlert = 6

• Age >= 21 years old <= 70 years old

• Willingness to abstain from drug use for the duration of the study

Exclusion Criteria:

• The following unstable medical conditions:

  • Heart disease
  • Seizures
  • Cancer
  • Thyroid disease (okay if controlled with medication)
  • Diabetes
  • Hepatitis B or C or Liver disease
  • Glaucoma
  • Kidney disease or urinary retention
  • History of stroke
  • An ulcer in the past year
  • Active use of an inhaler for Asthma or chronic obstructive pulmonary disease (COPD)

• Medications

  • Use of medications that are inducers of nicotine metabolizing enzyme CYP2A6 (Example: rifampicin, carbamazepine, phenobarbital, and other anticonvulsant drugs).
  • Use of sympatholytic medications for cardiovascular conditions including hypertension (Example: beta and alpha-blockers).
  • Concurrent use of nicotine-containing medications (Example: nicotine patch, lozenge, gum).
  • Any stimulant medications (example: Adderall) generally given for attention deficit hyperactivity disorder (ADHD) treatment.

• Other/Misc. Health Conditions

  • Oral thrush
  • Fainting (within the last 30 days)
  • Other "life threatening illnesses" as per principal investigator and/or study physician's discretion

• Pregnancy

  • Pregnancy (self-reported and urine pregnancy test)
  • Breastfeeding (determined by self-report)
  • Women of childbearing potential must be using an acceptable method of contraception

• Concurrent participation in another clinical trial.

• Inability to read and write in English

• Planning to quit smoking or vaping within the next 60 days

• A known propylene glycol/vegetable glycerin allergy

• Uncomfortable with getting blood drawn

• Recent onset or change (worsening) in cough, fever and/or abdominal symptoms (vomiting or pain) in the past two weeks