Antipyretic, analgesic and anti-inflammatory effects of delta 9-tetrahydrocannabinol in the rat

The effects on body temperature produced by graded doses of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and phenylbutazone were compared in both normal and pyretic rats. Dose related hypothermic responses were produced by the oral administration of Δ⁹-THC in normal animals. Moreover, Δ⁹-THC significantly reduced elevated temperatures in yeast-induced pyretic rats to near normal levels at doses which exhibited little hypothermic activity in normal rats. The oral antipyretic potency of Δ⁹-THC was approximately 2 times that of phenylbutazone. The comparative oral antinociceptive activity of Δ⁹-THC and selected narcotic and non-narcotic analgesics was determined by the increase in response latency to pressure applied to normal and yeast-inflamed paws. Δ⁹-THC administered orally was essentially inactive at dose levels below those producing pronounced central nervous system depression. The oral anti-inflammatory efficacy of Δ⁹-THC was compared to phenylbutazone and acetylsalicylic acid. Δ⁹-THC was ineffective in inhibiting carrageenin-induced edema of the rat paw following acute or chronic administration.