Method of simultaneously enhancing analgesic potency and attenuating

Abstract

This invention relates to a method of selectively enhancing the analgesic potency of morphine and other clinically used bimodally-acting opioid agonists and simultaneously attenuating development of physical dependence, tolerance and other undesirable side effects caused by the chronic administration of said bimodally-acting opioid agonists comprising the co-administration of a bimodally-acting opioid agonist which activates both inhibitory and excitatory opioid receptor-mediated functions of neurons in the nociceptive (pain) pathways of the nervous system and an opioid receptor antagonist which selectively inactivates excitatory opioid receptor-mediated side effects. This invention also relates to a method of using excitatory opioid receptor antagonists alone to block the undesirable excitatory side effects of endogenous bimodally-acting opioid agonists which may be markedly elevated during chronic pain. This invention further relates to a method of long-term treatment of previously detoxified opiate, cocaine and alcohol addicts utilizing said excitatory opioid receptor antagonists, either alone or in combination with low-dose methadone, to prevent protracted physical dependence, and to compositions comprising an excitatory opioid receptor antagonist of the invention and a bimodally-acting opioid agonist.