title: Modification of the response to opioid and nonopioid drugs by chronic opioid antagonist treatment.
abstract: Chronic exposure to opioid antagonists increases the analgesic actions of opioids such as morphine. In the present studies, morphine's analgesic potency was increased (supersensitivity) following an 8 day subcutaneous naltrexone implant in mice, but not following a 1 day implant. Supersensitivity was maximal 24hr following the 8 day implant and declined linearly and had returned to control levels by 120hr. Implantation of naltrexone pellets for 8 days was found to increase the relative analgesic potency of methadone by 120%, while the lethal potency of cocaine was slightly (19%), but significantly, decreased. In contrast, identical treatment did not alter the potency of the benzodiazepine alprazolam to induce ataxia.
authors: Department of Pharmaceutical Sciences, College of Pharmacy & Allied Health Professions, St. John's University, Jamaica, NY 11439.
authors: B C
authors: BC
authors: Yoburn
authors: C E
authors: CE
authors: Inturrisi
mesh_terms: D000525:Alprazolam; D000698:Analgesia; D000818:Animals; D001259:Ataxia / Q000139:chemically induced; D003042:Cocaine / Q000494:pharmacology; D004343:Drug Implants; D007700:Kinetics; D008297:Male; D008691:Methadone; D051379:Mice; D009020:Morphine; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology*
chemical_list: D004343:Drug Implants; D009294:Narcotics; D009270:Naloxone; D009020:Morphine; D003042:Cocaine; D008691:Methadone; D000525:Alprazolam