High Activity of Potent Analgesics on Conditioned Rat Tranquilizer Test

Abstract

The analgesics codeine, morphine, and 1-14-hydroxydihydromorphinone (Numorphan) produced inhibition of the conditioned avoidance-escape response in rats, a widely used tranquilizer test. The potencies in blocking the conditioned response correlated roughly with the analgesic potencies determined in mice by thehot-plate method, and with figures reported in the literature for analgesia in man. The very potent analgesic, l-14-hydroxydihydro-morphinone, exhibited by subcutaneous injection slightly more conditioned response blocking activity than perphenazine, one of the most active tranquilizers now in clinical use, and much more activity than morphine.