Other than a few FDA-approved cannabinoid-based medications—Sativex, Marinol, and Epidiolex—cannabis products meant for medical use are recreational cannabis products that may lack rigorous safety, dosing, and efficacy studies essential for medical drugs.

Numerous clinical trials for cannabinoid-based medicines are underway, including a recently published Phase 1 multiple-dose study of a standardized THC-dominant product.

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Canopy Growth researchers looked at the safety and pharmacokinetics of one of the company’s standardized THC-dominant products meant for medical purposes.

The capsules tested used cannabis resin extracted by supercritical carbon dioxide and diluted in medium-chain triglycerides and contained 2.5 mg THC and <0.25 mg CBD.

Participants received up to 20 mg THC daily for seven days, which was found to be safe with no serious adverse events noted. Almost two-thirds of participants experienced at least one mild to moderate adverse event, which included sleepiness, lethargy, headache, paranoia, and night sweats. Most of these occurred on the first day of treatment, then dropped off significantly, leading the authors to conclude that slow titration from low doses of THC might improve tolerability.

The study’s limitations include the small sample size—only 41 people participated—and the inclusion of only healthy adults.

As well, no detectable THC or its psychoactive metabolite, 11-hydroxy-THC, was measured in most plasma samples or urine samples over the course of the study, suggesting low bioavailability.

The maximum plasma concentration of a secondary metabolite, 11-carboxy-THC, occurred about two hours after dosing and accumulated over the course of the study.

While 11-carboxy-THC was low in urine samples of all participants over the seven-day dosing study, three of the participants had a positive urine drug screen for 11-carboxy-THC (>50 ng/mL) even many days after the study ended, suggesting that urinary excretion is relatively slow.