Nalbuphine: A narcotic used as a pain medication. It appears to be an agonist at kappa opioid receptors and an antagonist or partial agonist at mu opioid receptors.Morphinans: Compounds based on a partially saturated iminoethanophenanthrene, which can be described as ethylimino-bridged benzo-decahydronaphthalenes. They include some of the OPIOIDS found in PAPAVER that are used as ANALGESICS.Butorphanol: A synthetic morphinan analgesic with narcotic antagonist action. It is used in the management of severe pain.Sesame Oil: The refined fixed oil obtained from the seed of one or more cultivated varieties of Sesamum indicum. It is used as a solvent and oleaginous vehicle for drugs and has been used internally as a laxative and externally as a skin softener. It is used also in the manufacture of margarine, soap, and cosmetics. (Dorland, 28th ed & Random House Unabridged Dictionary, 2d ed)Methadyl Acetate: A narcotic analgesic with a long onset and duration of action.Analgesics, Opioid: Compounds with activity like OPIATE ALKALOIDS, acting at OPIOID RECEPTORS. Properties include induction of ANALGESIA or NARCOSIS.Narcotic Antagonists: Agents inhibiting the effect of narcotics on the central nervous system.Pentazocine: The first mixed agonist-antagonist analgesic to be marketed. It is an agonist at the kappa and sigma opioid receptors and has a weak antagonist action at the mu receptor. (From AMA Drug Evaluations Annual, 1991, p97)Receptors, Opioid, kappa: A class of opioid receptors recognized by its pharmacological profile. Kappa opioid receptors bind dynorphins with a higher affinity than endorphins which are themselves preferred to enkephalins.Morphine: The principal alkaloid in opium and the prototype opiate analgesic and narcotic. Morphine has widespread effects in the central nervous system and on smooth muscle.Receptors, Opioid, mu: A class of opioid receptors recognized by its pharmacological profile. Mu opioid receptors bind, in decreasing order of affinity, endorphins, dynorphins, met-enkephalin, and leu-enkephalin. They have also been shown to be molecular receptors for morphine.Tramadol: A narcotic analgesic proposed for severe pain. It may be habituating.