Comparison of the Analgesic Effects of Dronabinol and Smoked Marijuana in Daily Marijuana Smokers

The following study is designed to determine the analgesic efficacy of smoked marijuana (0, 1.98, and 3.56% THC) and oral THC (0, 10, and 20 mg) in the Cold-Pressor Test (CPT), a laboratory model of pain which has predictive validity for clinical use of analgesics. Oral THC (dronabinol) is known to have a slower onset and longer duration of action compared with smoked marijuana. Therefore, the analgesic effects of oral THC is expected to peak later and last longer than effects produced by smoked marijuana.

Laboratory animal studies have demonstrated the analgesic effects of drugs which act on the cannabinoid system, however, these effects have et to be clearly elucidated in humans. To better understand the potential clinical application of cannabinoids for pain management, the following study is designed to determine the analgesic efficacy of smoked marijuana (3.56% THC) and oral THC (20 mg) in the Cold-Pressor Test (CPT), a laboratory model of pain which has predictive validity for clinical use of analgesics. Non-treatment seeking marijuana smokers will be recruited for a five-session study during which the analgesic, subjective, and physiologic effects of cannabinoids will be evaluated. Determining the efficacy of cannabinoids in an experimental model of pain will provide important endpoints (i.e., dose, route of administration, time course) or this effect to further investigate the potential role for clinical use of smoked marijuana and/or oral THC as analgesics.

Participants received placebo capsules and smoked inactive marijuana (0% THC) on 1 of 5 outpatient sessions in randomized order.

Participants received low dose Dronabinol + inactive marijuana (0% THC) on 1 of 5 outpatient sessions in randomized order.

Participants received High dose Dronabinol + inactive marijuana (0% THC) on 1 of 5 outpatient sessions in randomized order.

Participants received placebo + low THC marijuana (1.98% THC) on 1 of 5 outpatient sessions in randomized order.

Participants received placebo + smoked high THC marijuana (3.56 % THC) on 1 of 5 outpatient sessions in randomized order.

Change in pain tolerance from baseline (in seconds) as a function of drug condition. The cold pressor test was administered during each session to examine changes in pain threshold (how many seconds it takes for a participant to begin feeling pain after cold water immersion).

Inclusion Criteria: Adults between the ages of 21-45 Current marijuana use Able to perform study procedures Women practicing an effective form of birth control Exclusion Criteria: Female subjects who are currently pregnant or breastfeeding Current,repeated illicit drug use other than marijuana Presence of significant medical illness History of heart disease Request for drug treatment Current parole or probation Recent history of significant violent behavior

Cooper ZD, Comer SD, Haney M. Comparison of the analgesic effects of dronabinol and smoked marijuana in daily marijuana smokers. Neuropsychopharmacology. 2013 Sep;38(10):1984-92. doi: 10.1038/npp.2013.97. Epub 2013 Apr 22.