OPRM1 and Meniere disease: The combination of phentanyl (a synthetic primary MOR agonist 100 times more potent than morphine) and droperidol (an antidopaminergic drug used as an antiemetic and antipsychotic) has been used for the treatment of Ménière's disease crises; this mixture has a rapid action and results in a complete suppression of vestibular activity in normal subjects and in those with Ménière's disease [32].