On the narcotic cuing action of fentanyl and other narcotic analgesic drugs.

Using a food-reinforced two-levers operant procedure, rats could be trained to discriminate fentanyl (1.25 mg/kg, p.o., t-60') from solvent (1 ml/100 g B.W., p.o.,t60)treatment. The administration of the other narcotic analgesics bezitramide, dextromoramide, methadone and morphine produced a dose-related stimulus generalization with the standard fentanyl treatment. The results further evidence the validity of the narcotic cue.