Short-Term Cardiovascular Effects of E-Cigarettes: Influence of E-Liquid pH

NCT04449510 | Completed DMC

• 2 other identifiers: 20-305975U54HL147127-09
• Study Type: interventional
• Target: 14
• Locations: 1 country
• Sites: 2

Brief Summary

This study will examine the short-term cardiovascular (CV) effects of e-liquid pH in a randomized, crossover clinical and behavioral pharmacology study of experienced adult e-cigarette users (N=21). The specific aim is to determine the impact of e-cigarette pH levels on nicotine pharmacology, systemic exposure to toxic volatile organic compounds (VOCs), and short-term cardiovascular effects.

Conditions

Cardiovascular Risk Factor; Nicotine Dependence

Keywords

E-Cigarettes; Vaping; E-Cig Mods

Outcome Measures

Primary Outcomes (7)

• Mean Blood Nicotine Level

  Concentration of plasma nicotine (ng/ml) will be used to assess differences across the three e-liquid pH levels.

  Day 1 of each Arm

• Mean Saliva pH

  Participant saliva pH will be measured before and during outpatient stay.

  Day 1 of each Arm

• Mean Heart Rate

  Participant heart rate will be measured in beats per minute throughout the outpatient stay.

  Day 1 of each Arm

• Mean Skin Blood Flow

  Participant skin blood flow will be measured by product of average blood cell velocity and concentration in mL/min during outpatient stay.

  Day 1 of each Arm

• Mean scores on the Minnesota Nicotine Withdrawal Scale (MNWS)

  The investigators will compile a score for the subjective effect of withdrawal using the sum of points scored on the Minnesota Nicotine Withdrawal Scale (MNWS), where a higher score (score range from 0 points to 60 points) indicates a higher intensity of the indicated subjective effect.

  Day 1 of each Arm

• Mean scores on the Questionnaire of Smoking Urges (QSU-Brief)

  The investigators will compile a score for the subjective effect of craving using the sum of points scored in the two subscales (intention and desire to engage in smoking behavior that is anticipated as pleasant, and anticipation of relief from negative affect through smoking) of the Questionnaire of Smoking Urges (QSU-Brief), where a higher score (score range from 10 points to 70 points) indicates a higher intensity of the indicated subjective effect.

  Day 1 of each Arm

• Mean scores on the Cigarette Evaluation Scale (mCES)

  The investigators will compile a score for the subjective effect of reward using the sum of points scored in the five subscales (Smoking Satisfaction - score range from 1 point to 7 points; Psychological Reward - score range from 5 points to 35 points; Aversion - score range from 2 points to 14 points; Enjoyment of Respiratory Tract Sensations - score range from 2 points to 14 points; and Craving Reduction - score range from 1 point to 7 points) of the modified Cigarette Evaluation Scale (mCES), where a higher score indicates a higher intensity of the indicated subjective effect.

  Day 1 of each Arm

Secondary Outcomes (3)

• Mean puffs per minute

  Day 1 of each Arm

• Mean seconds per puff

  Day 1 of each Arm

• Mean time between puffs

  Day 1 of each Arm

Study Arms (3)

E-liquid pH 5, 7, or 9

OTHER

Using an electronic cigarette, the participant will complete a standardized vaping session using 1 of 3 assigned e-liquid pH.

Other: Electronic Cigarette

1 of the other 2 remaining e-liquid pH

OTHER

Using an electronic cigarette, the participant will complete a standardized vaping session using 1 of the other 2 assigned e-liquid pH.

Other: Electronic Cigarette

Remaining e-liquid pH

OTHER

Using an electronic cigarette, the participant will complete a standardized vaping session using the remaining assigned e-liquid pH.

Other: Electronic Cigarette

Interventions

Electronic Cigarette OTHER

E-cigarette Device: The delivery device will be a variable wattage all-in-one device with operating wattage of 7.0 - 75.0 W. The device will be set at 10 watts for the study visits.

1 of the other 2 remaining e-liquid pH; E-liquid pH 5, 7, or 9; Remaining e-liquid pH

Eligibility Criteria

• Age: 21 Years - 70 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Heart rate \< 105 beats per minute (BPM)\*
• Systolic Blood pressure \<160 and \> 90\*
• Diastolic Blood Pressure \<100 and \> 50\*
• Body Mass Index (BMI) \< 38.0 (at investigator's discretion for higher BMI if no other concurrent health issues)
• \*considered out of range if both machine and manual readings are above/below these thresholds
• Use e-cigarettes on at least 15 days in the past 30 for at least 3 months
• Smoke 10 or fewer cigarettes/tobacco products per day in the last 30 days
• Willing to use mod e-cigarette
• Willing to abstain from tobacco product use for night before study
• Age: \> 21 years old and \< 70 years old
• Using e-liquid \> 0mg/ml nicotine
• Saliva cotinine of ≥ 30 ng/ml or NicAlert=6 (in cases where lab turn around time will delay study procedure)

You may not qualify if:

• Seizures
• Cancer
• Hepatitis B or C or Liver Disease
• Oral Thrush
• Heart disease
• Glaucoma
• Kidney disease or urinary retention
• Diabetes
• High Blood Pressure (taking sympatholytic medications such as alpha and beta blockers)
• History of stroke
• An ulcer in the past year
• Thyroid disease (okay if controlled with medication)
• Active use of an inhaler for asthma or Chronic Obstructive Pulmonary Disease (COPD)
• Psychiatric conditions
• Current or past schizophrenia, and/or current or past bipolar disorder

Sponsors & Collaborators

• University of California, San Francisco: lead
• National Institutes of Health (NIH): collaborator
• Food and Drug Administration (FDA): collaborator
• National Heart, Lung, and Blood Institute (NHLBI): collaborator

Study Sites (2)

Zuckerberg San Francisco General Hospital

San Francisco, California, 94110, United States

Location

University of California, San Francisco

San Francisco, California, 94143, United States

Location

MeSH Terms

Conditions

Tobacco Use Disorder; Vaping

Interventions

Electronic Nicotine Delivery Systems

Condition Hierarchy (Ancestors)

Substance-Related Disorders; Chemically-Induced Disorders; Mental Disorders; Smoking; Behavior

Intervention Hierarchy (Ancestors)

Smoking Devices; Manufactured Materials; Technology, Industry, and Agriculture

Study Officials

• Gideon St. Helen, PhD

  University of California, San Francisco

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 24, 2020
• First Posted: June 26, 2020
• Study Start: January 4, 2021
• Primary Completion: July 31, 2024
• Study Completion: July 31, 2024
• Last Updated: July 15, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will share

Locations

US (2)