Modulation of THC Effects by CBD: a Dose-ranging Study

Despite more than 40 years of research on the active compounds present in the cannabis plant, the influence of CBD consumption on the metabolism, pharmacology, and behavioral effects of THC remains fragmentary and scarcely documented in vivo in humans. Cannabis users are currently encouraged to choose products containing CBD, but evidence is lacking regarding its potential benefits when consumed jointly with THC across different ratios. Given the recent cannabis legalization in Canada and the widespread use of inhalation as the preferred mode of administration for non-therapeutic cannabis, closing this knowledge gap will help ensure public safety and allow regulatory bodies and public health authorities to elaborate more refined cannabis use guidelines and harm reduction strategies. It will also empower people who use cannabis to make more informed purchasing decisions and will drive the incubation of future research endeavors in the fields of medical and social sciences. The aim of this study is to improve our understanding of the (acute) behavioral and pharmacological effects of different doses of CBD administered concomitantly with THC via inhalation in individuals who engage in occasional cannabis use, taking into consideration multiple factors that can modulate such effects. This study will put to the test conceptions surrounding the interaction between specific cannabinoids by evaluating the role of CBD on the modulation of THC's effects pertaining to cognition, behavior, subjective experience, and physiological parameters.

Inclusion criteria

• Between 21 and 49 years of age, inclusively;
• Have used cannabis at least once in their lifetime and have used cannabis three days or less in the 30 days prior to enrollment;
• Be able to provide a signed informed consent;
• Willing to comply with study procedures and requirements as per protocol;
• Have a forced expiratory volume in first second (FEV) less than or equal to 90 %;
• Able to communicate and understand English or French language;
• For female participants:

a. No childbearing potential, defined as: i. postmenopausal (12 months of spontaneous amenorrhea and ≥ 45 years of age); or ii. Documented surgically sterilized (i.e., tubal ligation, hysterectomy, or bilateral oophorectomy); or b. For female of childbearing potential: i. Must have negative pregnancy test result at screening and at subsequent visits.

ii. AND have no pregnancy plan while on the study iii. AND must agree to use a medically accepted method of birth control throughout the study.

Exclusion criteria

Participants will be excluded if any of the following criteria are met:

• Any disabling medical condition, as assessed by medical history, physical exam, vital signs and/or laboratory assessments that, in the opinion of the study physician, precludes safe participation in the study or the ability to provide fully informed consent;
• Severe psychiatric condition (history of schizophrenia, schizoaffective disorder or bipolar disorder; current acute psychosis, mania or current suicidality based on the Mini International Neuropsychiatric Interview);
• Any other disabling, unstable or acute mental condition that, in the opinion of the study physician, precludes safe participation in the study or ability to provide fully informed consent;
• Known chronic liver disease or aspartate transaminase/alanine transaminase (AST/ALT) two times higher than upper limit of normal values at screening visit;
• Blood pressure higher than 130/80 mmHg;
• Kidney disorders;
• Bleeding disorders;
• Current moderate or severe DSM-5 substance use disorder (except nicotine) according to SCID-V;
• Currently pregnant, breastfeeding or planning to become pregnant either at screening or while enrolled in the study;
• Pending legal action or other reason that, in the opinion of the study physician, might prevent study completion;
• Use of medication within 7 days of experimental sessions; which, in the opinion of the Investigator, may interact with cannabis.
• Participation in clinical studies or undergoing other investigational procedure involving cannabis or cannabinoids administration within 30 days prior to randomization.
• Resting heart rate over 100 beats per minute.
• Current body mass index (BMI) over 29.9 kg/m2.
• Any clinically significant electrocardiogram abnormalities at screening visit.