opioid analgesic
any opioid used clinically to reduce both the sensation of pain and the emotional response to pain. This analgesia results from agonist activity at the mu opioid receptor. Codeine, dihydrocodeine, propoxyphene, and hydrocodone are among opioids used for the relief of mild to moderate pain; severe pain is managed with more potent agents, such as morphine, meperidine, oxycodone (U.S. trade name: OxyContin), and levorphanol. Methadone, fentanyl, and buprenorphine are potent analgesics that have additional uses. Side effects associated with opioid analgesics include nausea and vomiting, constipation, sedation, and respiratory depression; many also have the potential for abuse and dependence. Also called narcotic analgesic.