“Given the use of cannabis as an analgesic by a broadening age range of patients, the aim of this study was to determine whether the antinociceptive effects of Δ9-tetrahydrocannabinol (THC) differ by age.
On the tail withdrawal test, THC was significantly more effective in middle-aged adult than in young adult rats and significantly less effective in adolescent than in young adult rats.
Sex differences in THC’s antinociceptive effects were consistent across the 3 ages examined, with greater THC effects observed in females than males of each age. Age-related differences in THC’s locomotor-suppressing effect were also observed, with the greatest effect in young adult female rats. Serum THC levels were slightly higher in adolescent than in young adult rats, and levels of the active metabolites 11-OH-THC and cannabinol, as well as the inactive metabolite 11-nor-9-carboxy-THC, did not differ between adolescent and young adult rats.
These results suggest that the pain-relieving effects of THC may be more limited in adolescents than in adults and that these age-related differences in THC effect are not attributable to differential absorption or metabolism of THC.”