The overarching goal of this double-blind, placebo-controlled, crossover study is 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. This protocol includes two sub-studies, each randomizing 20 men and women aged 65 years or older to receive two administration routes of THC; oral administration and vaporized administration.
This is a double-blind, placebo-controlled, crossover study, with two sub-studies each focusing on different routes of THC administration. Oral THC Sub-Study: 20 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. Vaporized THC Sub-Study: 20 men and women aged 65 years or older will be randomized to two doses of vaporized THC (2 mg and 4 mg). Across three 8-hour test sessions, participants will receive a random sequence of 3 conditions: 2 mg vaporized THC; 4 mg vaporized THC; and vaporized placebo. For both the Oral and Vaporized THC Sub-Studies, 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. General adverse, cardiovascular, and cognitive/psychomotor effects of THC will be thoroughly assessed with behavioral, physiological, and neuropsychological methods.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
20
Dronabinol 5 mg
Dronabinol 10mg
2mg Purified THC in an ethanolic solution
4mg Purified THC in an ethanolic solution
Oral placebo and/or vaporized saline
VA Connecticut Healthcare System
West Haven, Connecticut, United States
RECRUITINGPeak concentration (Cmax)
Serial blood samples will be collected for plasma levels of THC; its phase I metabolite 11-hydroxy-THC (OH-THC); phase II metabolite 11-nor-9-carboxy-THC (THC-COOH); and THC-COOH glucuronide. For THC and all other analytes, the peak concentration (Cmax) will be derived using a linear noncompartmental analysis.
Time frame: Up to 8 hours
Time to attain Cmax concentration (Tmax)
Serial blood samples will be collected for plasma levels of THC; its phase I metabolite 11-hydroxy-THC (OH-THC); phase II metabolite 11-nor-9-carboxy-THC (THC-COOH); and THC-COOH glucuronide. For THC and all other analytes, the time to attain Cmax concentration (Tmax) will be derived using a linear noncompartmental analysis.
Time frame: Up to 8 hours
Area under the plasma concentration-time curve (AUC0-8h)
Serial blood samples will be collected for plasma levels of THC; its phase I metabolite 11-hydroxy-THC (OH-THC); phase II metabolite 11-nor-9-carboxy-THC (THC-COOH); and THC-COOH glucuronide. For THC and all other analytes, the area under the plasma concentration-time curve (AUC0-8h) will be derived using a linear noncompartmental analysis.
Time frame: Up to 8 hours
Nociception
Multimodal quantitative sensory testing (QST) will be used ensure that various types of afferent fibers are engaged, so that the analgesic efficacy of THC can be comprehensively investigated. A composite pain sensitivity measure as a Z-score (ranging from -1 to +1) will be derived from the QST battery, with greater scores indicating a higher sensitivity to pain.
Time frame: Up to 8 hours
Abuse Liability
A modified Multiple-Choice Procedure (MPC) will be used to measure abuse liability. The MCP was developed and validated by Roland Griffiths to efficiently assess drug reinforcement - including cannabinoid-induced reinforcement. In each of the 6 experimental sessions, participants will choose between forfeiting or receiving escalating sums of money, on a scale of values between -$20.00 and $20.00; or re-receiving the study medication assigned for that day. The primary outcome will be the crossover point, the value at which the participant chooses money rather than the study medication, which will be determined for each session.
Time frame: Up to 8 hours
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