Electric shock titration in squirrel monkeys following administration of nantradol, levonantradol, or N-methyl levonantradol.

The effects of some cannabinoid-related analgesics were examined in squirrel monkeys responding under a schedule of shock titration. Nantradol (0.1-0.3 mg/kg), levonantradol (0.03-0.1 mg/kg), or N-methyl levonantradol (0.01-0.03 mg/kg) increased the level at which shock was maintained, but did not change rates of responding. Nantradol effects were not blocked by naloxone (0.3-3.0 mg/kg), but they were attenuated following daily administration of nantradol.