Enadoline is a drug which acts as a highly selective κ-opioid agonist. In human studies, it produced visual distortions and feelings of dissociation, reminiscent of the effects of salvinorin A. It was looked at as a potential analgesic, but abandoned because of the dose-limiting effects of dysphoria, which could be expected from a κ-opioid agonist. There was mention of its potential in treating comatose head injury or stroke victims, where that type of side effect would be immaterial. Enadoline significantly increased measures of sedation, confusion and dizziness, produced visual distortions and feelings of depersonalization, and increased urinary output.Hydromorphone produced prototypic mu opioid effects including respiratory depression, miosis, and euphoria. Butorphanol was most similar to hydromorphone and shared few effects with enadoline.