Overview
This double-blind, placebo-controlled, crossover study aims to characterize the pharmacokinetic (PK) and pharmacodynamic (PD) effects of the main analgesic and psychoactive constituent of cannabis, delta-9 tetrahydrocannabinol (THC), among older adults - the fastest growing population of cannabis consumers, and the most likely age cohort to use cannabinoids to relieve pain.
Description
This is a double-blind, placebo-controlled, crossover study, commencing with an oral THC Sub-Study. Following the completion of this sub-study, the Primary Study will commence.
Oral THC Sub-Study: 10 men and women aged 65 years or older, will be randomized to two doses of oral THC (5 mg and 10 mg). Across three, 8-hour test sessions, participants will receive a random sequence of 3 conditions: 5 mg oral THC; 10 mg oral THC; oral placebo.
Primary Study: 20 men and women aged 65 years or older will be randomized to two doses of oral THC (5 mg and 10 mg) and vaporized THC (2 mg and 4 mg). Across six 8-hour test sessions, participants will receive a random sequence of 6 conditions: 5 mg oral THC; 10 mg oral THC; oral placebo; 2 mg vaporized THC; 4 mg vaporized THC; and vaporized placebo.
For both the sub-study and primary study, blood samples will be regularly collected from an intravenous line, up to 8 hours post-dose, and at 24 hours post-dose, to assess the PK of THC and its phase I and II metabolites. PD effects of THC on pain will be measured with Quantitative Sensory Testing (QST), a psychophysical technique used to reliably measure pain sensitivity and investigate pain modulatory mechanisms. The abuse liability of THC will be measured using an established drug reinforcement paradigm.
Eligibility
Inclusion Criteria:
- Healthy male and female participants aged 65 ≥ years old
- Prior exposure to THC or cannabis least once in the last 10 years; 1-10 times in the last 20 years; or more than 20 times in their lifetime
- Capable of providing informed consent in English.
Exclusion Criteria:
- Meeting DSM-5 criteria for psychiatric/substance use disorders (SUD) other than tobacco use disorder, within the last year
- Current use of cannabinoid products, as evidenced by a urine drug screen
- Having a history of treatment for cannabis use disorder
- History of intent or current intent of abstaining from cannabis use
- Clinically significant medical disorders (e.g. liver/kidney dysfunction, immunosuppressing conditions, history or presence of epilepsy, seizures, head trauma with loss of consciousness)
- Medical conditions that increase the risk of respiratory problems (e.g. COPD, asthma, recuring bronchitis, reactive airway disorder)* (does not apply to the Oral THC Sub-Study)
- History of environmental sensitivities (e.g. bronchospastic allergies, multiple chemical sensitivities) or other airway sensitivities that require the use of an epi pen*(does not apply to the Oral THC Sub-Study)
- Neurological conditions that may change the response to nociceptive stimuli (e.g., stroke, neuropathy), or that lead to loss of balance, evidenced by a neuro-sensory exam
- Contraindications for exposure to nociceptive stimuli, such as untreated hypertension
- Current regular use of drugs known to affect pain, or that are prominent inducers or inhibitors of CYP2C9, CYP3A4, or UGTA19 (e.g., carbamazepine, valproate, fluvoxamine, and paroxetine)
- Major neurocognitive disorders precluding participation, evidenced by a clinical exam
- Abnormal EKG, arrythmia, vasospastic disease, chronic heart failure, or presence of a pacemaker
- Elevation of liver enzymes (ALT, AST) 2x the normal limit or higher
- Personal or family history of primary psychotic disorders, or mood disorders with psychotic features
- Current suicidal ideation
- Allergy or serious adverse reactions to sesame oil, THC, or cannabis
- Having received any drug as part of a research study within 30 days prior to receiving the study medication in the current study.