title: The search for a better analgesic.
mesh_terms: D000700:Analgesics / Q000037:antagonists & inhibitors / Q000138:chemical synthesis; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D003061:Codeine; D003932:Heroin; D006801:Humans; D004091:Hydromorphone; D007981:Levorphanol; D008614:Meperidine; D008691:Methadone; D009019:Morphinans; D009021:Morphine Dependence; D013329:Structure-Activity Relationship
chemical_list: D000700:Analgesics; D009019:Morphinans; D007981:Levorphanol; D003932:Heroin; D008614:Meperidine; D004091:Hydromorphone; D008691:Methadone; D003061:Codeine