A new class of analgesics is provided by substances that inhibit breakdown of endogenous substances such as enkephalins and/or endorphins. Analgesia is obtained in animals by inhibiting endogenous breakdown of enkephalins, or by internal injection of an inhibitor of enkephalin breakdown which itself serves as an analgesic. The analgesic effect of an enkephalin breakdown inhibitor is greatly enhanced by being combined with an Aspirin?-type drug. Specifically, D-phenylalanine as an enkephalin breakdown inhibitor provides excellent analgesia in animals without developing tolerance or addiction in the animal. The injection of a combination of D-phenylalanine and an Aspirin-like drug in an animal provides a greatly enhanced analgesia approaching the analgesia achieved by morphine.
CLASS OF ANALGESICS CONSISTING OF INHIBITORS OF BREAKDOWN OF ENDOGENOUS ENKEPHALIN AND/OR ENDORPHIN, AND COMBINATIONS OF SAID ANALGESICS WITH ANTIPYRETIC (ASPIRIN TYPE) DRUGS