Interactions in man of delta-9-tetrahydrocannabinol. II. Cannabinol and cannabidiol.

Oral doses of delta-9-tetrahydrocannabinol (THC) 20 mg, combined with placebo or with 40 mg dses of cannabinol (CBN) and cannabidiol (CBD), were given to volunteers. The combination of THC with CBN produced no detectable changes in the quality, intensity, or duration of the effects of THC alone. The THC-CBD combination tended to delay onset and prolong effects of THC, while making them somewhat more intense. Even this interactive effect was slight, providing no reason to abandon the current practice of basing doses of marihuana for clinical studies solely on THC content.