Relation between effects of cannabinoid derivatives on the twitch response of the isolated guinea-pig ileum and their psychotropic properties.

Summary The ability of Δ 6 -THC, five of its hydroxy metabolites and a number of synthetic cannabinoids were tested for their ability to reduce the response of a guinea-pig ileum to electrical stimulation. Good correlation was found between high activity in this test and observed psychotropic activity. Thus Δ 6 -THC and its 3”- and 7-hydroxy metabolites showed equal potency in the guinea-pig test with 5”-hydroxy-Δ 6 -THC showing lower activity. In behavioural tests, 3”-, 4”-, 5”- and 7-hydroxy-Δ 6 -THC showed high activity. THC analogues containing a methylated or acetylated phenol group or an aromatic carboxyl group were inactive in both tests.