Several years ago we reported that D-phenylalanine (DPA) and other inhibitors of the degradation of met-enkephalin can produce naloxone- reversible analgesia in animals and man (Ehrenpreis et. al, Adv. Pain Res. and Therap. 3:479, 1979). As an extension of this finding, Cheng and Pomeranz demonstrated that DPA potentiates acupuncture analgesia in mice (Pain 8:231, 1980). In collaboration with Dr. H. Hyodo, Osaka Medical School, we have carried out studies in a variety of human pain conditions. DPA given orally (2-4 grams) 30 minutes prior to acupuncture, significantly increases the duration of acupuncture analgesia in healthy human volunteers. The drug also potentiates acupuncture analgesia for low back, facial, knee and neck pain as well as pain of frozen shoulder. When used in conjunction with DPA, acupuncture analgesia for tooth extraction was also potentiated. These results in humans are consistent with animal findings that acupuncture analgesia results from mobilization of endorphins (primarily enkephalins) in the brain and that DPA enhances the levels of the peptides thereby potentiating the effectiveness of acupuncture analgesia.
