THE EVALUATION OF THE ANALGESIC ACTION OF PETHIDINE HYDROCHLORIDE (DEMEROL)

1. A new method for the evaluation of analgesics is described. 2. By the use of this method, comparison of morphine, diacetylmorphine, codeine and pethidine hydrochlorides has been made. 3. Pethidine hydrochloride has been found to possess one fifth to one sixth of the analgesic activity of morphine hydrochloride against mild pain stimuli, but to be ineffective against severe pain. 4. Aminopyrine and antipyrin are effective only in very large doses. Phenobarbitone sodium and aspirin have no analgesic action that can be detected by this method.