Are the endorphins active in clinical pain states? Narcotic antagonism in chronic pain patients

Abstract
To test the possibility of endorphin release in clinical pain states naloxone was given, alternate with saline, in a double-blind study to 10 patients with chronic neuralgia or low back pain. There was no significant alteration of the levels of spontaneous pain or heat pain thresholds. The endorphin system probably does not offer protection of any importance in chronic pain.