On the ability of narcotic antagonists to produce the narcotic cue.

The ability of narcotic antagonists to produce the narcotic cue was investigated in rats trained to discriminate fentanyl (0.04 mg/kg) from solvent. The partial antagonists pentazocine, cyclazocine and nalorphine were found to possess narcotic cuing activity whereas naloxone lacked any such action at doses up to 160 mg/kg. The relationship between the present findings and the ability of these drugs to produce opiate-like subjective effects in humans is discussed. The conclusion was reached that the experimental procedure used may contribute significantly to the preclinical evaluation of drug abuse liability.