Characterizing Drug Liking During Drug Administration in Peri-procedural Clinical Settings

Inclusion Criteria: * American Society of Anesthesiologists (ASA) physical status classification of I, II or III * Candidates who are expected to receive fentanyl up to 3 mcg/kg IBW for their scheduled for surgery or procedure Exclusion Criteria: * Craniofacial abnormalities * Known or suspected difficult intubation or mask ventilation * Known or suspected need for rapid sequence induction and intubation * Allergies or hypersensitivities to amisulpride or fentanyl * Clinically significant pulmonary disease, such as chronic obstructive lung disease requiring long-term oxygen therapy, or other conditions that, in the study team's judgment, may increase the risk of severe respiratory depression with opioid administration * History of long QT syndrome * Any heart rhythm other than normal sinus rhythm (including but not limited to atrial fibrillation, atrial flutter, paced rhythms, ventricular tachycardia, or any supraventricular tachycardia) * History of Torsades de Pointes * History of psychosis * History of movement disorders e.g. Parkinson's Disease * Past chronic use of anti-psychotics * Current use of amisulpride, droperidol, levodopa, lithium, clozapine, metoclopramide, benzodiazepines * Current use of opioids * History of opiate abuse within the last 3 years * Known or suspected severe chronic pain condition that require use of opiates or limit daily activities * History of pheochromocytoma * History of concomitant prolactin-dependent tumors e.g. prolactinoma, breast cancer * Pregnancy or nursing * Failure to satisfy the investigator of fitness to participate for any other reason