title: Chronic pain: levorphanol, methadone, and the N-methyl-D-aspartate receptor.
authors.forename: Jack P
authors.initials: JP
authors.lastname: McNulty
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D002908:Chronic Disease; D017051:Hospice Care; D006801:Humans; D007981:Levorphanol / Q000627:therapeutic use*; D008691:Methadone / Q000627:therapeutic use*; D016202:N-Methylaspartate / Q000187:drug effects*; D009294:Narcotics / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy*; D010166:Palliative Care; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*
chemical_list: D000701:Analgesics, Opioid; D009294:Narcotics; D016194:Receptors, N-Methyl-D-Aspartate; D007981:Levorphanol; D016202:N-Methylaspartate; D008691:Methadone