ABSTRACT: 1. After oral administration to mice, pethidine, Δ8-tetrahydrocannabinol (THC), Δ9-THC, a cannabis extract and cannabinol had a dose-dependent antinociceptive effect when measured by the hot-plate method. Cannabidiol was inactive at 30 mg/kg. Δ8-THC, Δ9-THC and pethidine did not differ significantly in potency, but Δ9-THC was 6·5 times more active than ... Continue Reading