Δ9-tetrahydrocannabinol attenuates oxycodone self-administration under extended access conditions.
Neuropharmacology June 1, 2019 Jacques D Nguyen, Yanabel Grant, Kevin M Creehan et al.
Combined Δ9-tetrahydrocannabinol (THC) and oxycodone produced additive pain-relieving effects while reducing opioid self-administration in rats. Male rats trained to self-administer oxycodone intravenously obtained fewer infusions after inhaling vaporized THC or receiving injected THC (0-10 mg/kg, i.p.) compared to vehicle. Follow-up tests showed dose-dependent reductions across different oxycodone doses, with an intact loading dose arguing against general behavioral suppression. In separate groups of male and female Wistar rats, tail withdrawal latency increased more after inhaled THC (50 mg/mL) plus oxycodone (100 mg/mL) than either alone; similar additive antinociception occurred with injected THC (5.0 mg/kg, i.p.) and oxycodone (2.0 mg/kg, s.c.). These additive effects suggest THC could enhance opioid therapeutic efficacy and reduce abuse.