A new method for the rapid measurement of analgesic activity in rabbits

A simple and rapid method is described for the screening of narcotic and non-narcotic analgesics in conscious rabbits. This method is based upon the increase in threshold by electrical stimulation of the ears of rabbit, by analgesics. A reliable dose-response and time-response relations were observed for both groups of analgesics. Naloxone did not produce a hyperalgesia when given alone. It antagonized, however, the analgesic activity of morphine without altering that of aspirin. From these results it is concluded that nociception induced by electrical stimulation of rabbit ears is a simple and rapid method for the screening of analgesics as well as their interactions with specific antagonists.