Facilitation of Development of Resistance to Morphine Analgesia by Desglycinamide 9 -Lysine Vasopressin

Abstract
Desglycinamide(9)-lysine vasopressin facilitates development of resistance to the analgesic action of morphine in mice if morphine is administered before the peptide. Desglycinamide(9)-lysine vasopressin is not a morphine antagonist, and does not appear to cause either hyperalgesia or alteration of the response to the technique used for evaluating analgesia.