Two extracts of Cannabis sativa herb, one being
cannabinoid-free (
ethanol) and the other containing the
cannabinoids (
petroleum), were shown to inhibit PBQ-induced writhing in mouse when given orally and also to antagonize
tetradecanoylphorbol acetate (TPA)-induced
erythema of mouse skin when applied topically. With the exception of
cannabinol (CBN) and delta 1-tetrahydrocannabinol (delta 1-THC), the
cannabinoids and
olivetol (their biosynthetic precursor) demonstrated activity in the PBQ test exhibiting their maximal effect at doses of about 100 micrograms/kg. delta 1-THC only became maximally effective in doses of 10 mg/kg. This higher dose corresponded to that which induced
catalepsy and is indicative of a central action. CNB demonstrated little activity and even at doses in excess of 10 mg/kg could only produce a 40% inhibition of PBQ-induced writhing.
Cannabinoid (CBD) was the most effective of the
cannabinoids at doses of 100 micrograms/kg. Doses of
cannabinoids that were effective in the
analgesic test orally were used topically to antagonize TPA-induced
erythema of skin. The fact that delta 1-THC and CBN were the least effective in this test suggests a structural relationship between
analgesic activity and antiinflammatory activity among the
cannabinoids related to their peripheral actions and separate from the central effects of delta 1-THC.