Exploring The Effect Of Cannabidiol On Cannabis Tolerance Using A Novel Vaporiser Device In Heavy Users (Stage 1)

NCT07471347 | Not Yet Recruiting

• 1 other identifier: R&D2025/050
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

Cannabis contains delta-9-tetrahydrocannabinol (THC), which causes intoxication. People who use cannabis frequently often develop tolerance, meaning they need to use more THC to feel the same effects. Cannabidiol (CBD) is another compound found in cannabis that is not intoxicating and may influence how THC affects the body and brain. This study will examine whether taking CBD changes how much THC heavy cannabis users consume to reach their usual level of intoxication. The study will also develop a new laboratory method that allows participants to safely and gradually self-administer THC using a vaporiser, similar to how cannabis is used in real-world settings. The study will include around 30 adults who use cannabis heavily. In the first stage, participants will take part in pilot sessions to help refine the THC administration procedure. In the second stage, participants will attend two study sessions and receive a single oral dose of CBD or placebo, in a random order. After this, they will inhale THC using a vaporiser and decide when to stop based on how intoxicated they feel. Researchers will measure how much THC is used, along with mood, mental health symptoms, thinking abilities, physical measures such as heart rate and blood pressure, and blood levels of THC and CBD. The results will help improve understanding of cannabis tolerance and whether CBD alters responses to THC in heavy cannabis users.

Conditions

Cannabis Intoxication

Keywords

Cannabis; THC; Delta-9-tetrahydrocannabinol

Outcome Measures

Primary Outcomes (1)

• Cannabis tolerance

  Change in THC cartridge weight

  From initiation of use until the participant reaches their desired level of intoxication (self-titrated), assessed up to 4 hours.

Secondary Outcomes (10)

• Cannabis tolerance (maximum)

  From initiation of use until the participant reaches their maximum tolerated level of intoxication (self-titrated), assessed up to 4 hours.

• Drug effects questionnaire (DEQ)

  Baseline; The timepoint at which the participant reaches their desired level of intoxication (self-titrated); The timepoint at which the participant reaches their maximum tolerated level of intoxication (self-titrated), assessed up to 4 hours.

• Visual analogue scales

  Baseline; The timepoint at which the participant reaches their desired level of intoxication (self-titrated); The timepoint at which the participant reaches their maximum tolerated level of intoxication (self-titrated), assessed up to 4 hours.

• Observer Rated Cannabis Intoxication Scale (ORCIS)

  Baseline; The timepoint at which the participant reaches their desired level of intoxication (self-titrated); The timepoint at which the participant reaches their maximum tolerated level of intoxication (self-titrated), assessed up to 4 hours.

• Cannabis withdrawal Scale (CWS)

  Baseline; The timepoint at which the participant reaches their desired level of intoxication (self-titrated); The timepoint at which the participant reaches their maximum tolerated level of intoxication (self-titrated), assessed up to 4 hours.

Study Arms (1)

Delta-9-tetrahydrocannabinol/Cannabidiol

EXPERIMENTAL

Delta-9-tetrahydrocannabinol/Cannabidiol (vaporised; self-administered by the participant, titrated to individual tolerability)

Drug: delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD)

Interventions

delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) DRUG

Vida T400:C20 Blueberry Cookies Medical Cannabis Cartridge (400mg delta-9-tetrahydrocannabinol and 20mg cannabidiol per cartridge)

Delta-9-tetrahydrocannabinol/Cannabidiol

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Adults, between 18 and 45 years old
• Heavy and frequent cannabis user: using 7-14 grams of high potency cannabis per week over the past month, and using cannabis on at least 5 days per week over the past month
• Positive urine drug screen (UDS) for cannabis
• Willing to abstain from cannabis use for 4 hours before any experimental session.
• Willing to eat two non-vegan full-fat yoghurts to aid drug absorption
• Providing written informed consent.

You may not qualify if:

• Dependent use of alcohol or illicit drugs (apart from cannabis or tobacco/nicotine)
• Not able to provide a UDS which is negative for illicit drugs (apart from cannabis)
• Not able to provide a negative alcohol breath test
• Personal or family history (first-degree) of psychosis or mania
• Currently prescribed antidepressant, mood-stabilising, antipsychotic or stimulant medication, or regular medication for a significant medical condition (e.g. antihypertensives, anticonvulsants, anticoagulants, or immunosuppressants)
• Diagnosis of a major medical or psychiatric illness that the study doctor considers inappropriate for the purposes of this study
• Female participants who are pregnant or mothers who are lactating
• Not willing to use an adequate form of contraception for the duration of the study
• Participant in another experimental medicine study or clinical trial within the past three months.

Sponsors & Collaborators

• King's College London: lead
• South London and Maudsley NHS Foundation Trust: collaborator

Study Sites (1)

King's Clinical Research Facility

London, United Kingdom

Location

MeSH Terms

Conditions

Marijuana Abuse

Interventions

Dronabinol; Cannabidiol

Condition Hierarchy (Ancestors)

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

Intervention Hierarchy (Ancestors)

Cannabinoids; Terpenes; Hydrocarbons; Organic Chemicals

Central Study Contacts

Edward Chesney, MRCPsych PhD

CONTACT

+4420 7836 5454; kingscrf@kcl.ac.uk

Study Design

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

Study Record Dates

• First Submitted: January 30, 2026
• First Posted: March 13, 2026
• Study Start: March 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: March 13, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)