[Effect of droperidol, aminazine and diazepam on the analgesic activity of leucine-enkephalin].

In experiments on rats it was shown that the neuroleptics droperidol (0.6 mg/kg) and aminazin (10 mg/kg) can potentiate the analgetic action of the endogenous morphine-like pentapeptide leucin-enkephalin administered into the brain ventricles at a dose of 50 micrograms. A statistically significant increase in the analgetic activity lf leucin-enkephalin given at a dose of 100 micrograms was induced only by droperidol. The tranquilizer diazepam (5 mg/kg) had no effect on the action lf leucin-enkephalin. Naloxon (2 mg/kg) removed the analgetic effect of leuchin-enkephalin administered both alone and after a preliminary injection od droperidol or aminazin.