OPRM1 and delirium: In practice, physicians typically use one or more medications to control delirium and agitation: benzodiazepines and propofol, which act as gamma aminobutyric acid type A (GABAA) receptor agonists, antipsychotic medications, such as haloperidol (a dopamine D2 receptor antagonist) or quetiapine (which is a dopamine D2 receptor and serotonin 5-HT receptor antagonist), and opioids, which act mainly as mu opioid receptor agonists (1, 30).