Recruiting
Phase 2

THC & Nicotine

Sponsor:

UCLA

Code:

NCT05999383

Conditions

THC

Cannabis

Cannabis Use

Cannabis Smoking

Tobacco Use

Eligibility Criteria

Sex: All

Age: 21 - 65

Healthy Volunteers: Accepted

Interventions

Cannabis

Nicotine

Pax Loose Leaf Vaporizer

Placebo Marijuana

Study Details

Brief summary:

This is a crossover, randomized, double-blinded clinical pharmacology study enrolling dual cannabis-tobacco smokers to better understand the combined effects of co-administering cannabis and tobacco. The project aims to describe the pharmacokinetics and pharmacodynamics of marijuana-tobacco co-administration by delivering THC and nicotine in various combinations. This foundational study will establish a research program focused on elucidating the public health consequences of marijuana-tobacco co-use.

Conditions

THC

Cannabis

Cannabis Use

Cannabis Smoking

Tobacco Use

Study ID

NCT05999383

Start date

Jul 1, 2025

Status verified date

Jan, 2026

Completion date

Feb 1, 2028

Anticipated

Primary completion date

Feb 1, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 21 - 65

Healthy Volunteers: Accepted

Inclusion Criteria:

  • 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 (BMI) ≤ 38.0 (at investigator's discretion for higher BMI if no other concurrent health issues)
  • Current regular user of cannabis who smokes or vapes cannabis or THC extracts at least three days a week for the past 3 months or more
  • Test positive for D-9-tetrahydrocannabinol (THC) at screening and self-report of cannabis use
  • Current user of inhaled forms of tobacco/nicotine (cigarette, cigars, e-cigarettes) who use the product daily for the past 3 months or more
  • Saliva cotinine ≥ 30 ng/mL

Exclusion Criteria:

  • 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
  • An ulcer in the past year
  • Active use of an inhaler for asthma or Chronic Obstructive Pulmonary Disease (COPD)
  • Hypertension if uncontrolled (meaning participant has a diagnosis, but they are not taking medication/under treatment (e.g., diet or exercise plan)
  • Drug/Alcohol Dependence

  • Alcohol or illicit drug dependence within the past 12 months (currently in treatment) with the exception of those who recently completed an alcohol/drug treatment program
  • Positive toxicology test at the screening visit (THC \& prescribed medications okay)
  • Opioid replacement therapy (including methadone, buprenorphine, or other)
  • Psychiatric conditions

  • Current or past schizophrenia, and/or current or past bipolar disorder
  • Major depression, current or within the past year
  • Major personality disorder
  • Participants with current or past minor or moderate depression and/or anxiety disorders will be reviewed by the PI \[study physician\] and considered for inclusion
  • History of psychiatric hospitalizations are not exclusionary, but study participation will be determined as per PI's \[study physician's\] approval
  • Current regular use of any psychiatric medications with the exception of Selective serotonin reuptake inhibitors (SSRI) and serotonin-norepinephrine reuptake inhibitors (SNRI) and current evaluation by the PI that the participant is otherwise healthy, stable, and able to participate
  • Congenital or acquired immunodeficiency disorders (i.e. HIV, congenital immune deficiency syndrome, chronic diseases)
  • Other disorders (i.e. ICU, malnutrition, immunosuppressive therapy)
  • Traumatic brain injury
  • Recent onset or change (worsening) in cough, fever and/or abdominal symptoms (vomiting or pain) in the past two weeks
  • Medications

  • Use of medications that are inducers of nicotine metabolizing enzyme CYP2A6 (Example: rifampicin, dexamethasone, phenobarbital, and other anticonvulsant drugs)
  • Concurrent use of nicotine-containing medications
  • Any stimulant medications (ex. Adderall) generally given for attention deficit hyperactivity disorder (ADHD) treatment
  • Other/Misc. Chronic Health Problems

  • Oral thrush
  • Fainting
  • Other "life threatening illnesses" as per study physician's discretion
  • Pregnancy

  • Pregnancy (self-reported and urine pregnancy test)
  • Breastfeeding (determined by self-report)
  • Concurrent participation in another clinical trial
  • Inability to communicate in English
  • History of marijuana-induced psychosis or paranoia after smoking marijuana
  • Scoring a 7 or higher on the Severity of Dependence Scale (SDS) for cannabis use
  • Planning to quit smoking or vaping within the next 60 days
  • Planning to quit cannabis use within the next 60 days
  • Uncomfortable with getting blood drawn
  • Willingness to abstain from tobacco smoking and all combustible products for 13 hours before admission
  • Willingness to abstain from smoking/ingestion of cannabis 13 hours before
  • Willingness to abstain from nicotine products 13 hours before each admission

Study Design

Enrollment

48 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Placebo marijuana and regular cigarette

Participants will vape a 50/50 mixture of placebo marijuana (0% THC) and regular cigarette (25.94 mg/g nicotine content)

experimental: Placebo marijuana and Very Low Nicotine Content cigarette

Participants will vape a 50/50 mixture of placebo marijuana (0% THC) and Very Low Nicotine Content cigarette (0.42 mg/g nicotine content)

experimental: Medium marijuana and regular cigarette

Participants will vape a 50/50 mixture of medium marijuana (<5% THC) and regular cigarette (25.94 mg/g nicotine content)

experimental: Medium marijuana and Very Low Nicotine Content cigarette

Participants will vape a 50/50 mixture of medium marijuana (<5% THC) and Very Low Nicotine Content cigarette (0.42 mg/g nicotine content)

experimental: High marijuana and regular cigarette

Participants will vape a 50/50 mixture of high marijuana (>10% THC) and regular cigarette (25.94 mg/g nicotine content)

experimental: High marijuana and Very Low Nicotine Content cigarette

Participants will vape a 50/50 mixture of high marijuana (>10% THC) and Very Low Nicotine Content cigarette (0.42 mg/g nicotine content)

experimental: High marijuana only

Participants will vape high marijuana (>10% THC)

experimental: Regular cigarette only

Participants will vape a regular cigarette (25.94 mg/g nicotine content)

Interventions

Cannabis

Participants will vape marijuana in varying doses from the PAX device

Nicotine

Participants will vape Regular and Very Low Nicotine content cigarettes from the PAX device

Pax Loose Leaf Vaporizer

In all arms, participants will be using the PAX Loose Leave Vaporizer.

Placebo Marijuana

Participants will vape placebo marijuana from the PAX device

Primary outcome measure

  • Change in peak plasma concentration of THC [ Time Frame: From Baseline to Day 1 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 1 to Day 2 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 2 to Day 3 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 3 to Day 4 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 4 to Day 5 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 5 to Day 6 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 6 to Day 7 ]
  • Change in peak plasma concentration of THC [ Time Frame: From Day 7 to Day 8 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Baseline to Day 1 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 1 to Day 2 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 2 to Day 3 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 3 to Day 4 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 4 to Day 5 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 5 to Day 6 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 6 to Day 7 ]
  • Change in Peak plasma concentration of nicotine [ Time Frame: From Day 7 to Day 8 ]

Central Contacts and Locations

Central contacts

Locations

Zuckerberg San Francisco General Hospital

Recruiting

San Francisco, California, United States, 94110

Contacts

Principal Investigator:

Gideon St. Helen, PhD

More Information

Sponsor

University of California, San Francisco

Last update posted

Jan 7, 2026

Last verified

Jan, 2026

Keywords

  • THC
  • Cannabis
  • Marijuana
  • Nicotine
  • Vape

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of California, San Francisco on 2026-01-07.