Pilot Study 1: Efficacy and Safety of Sublingual Dexmedetomidine (BXCL501) for the Treatment of Agitation in the Emergency Department

Inclusion Criteria: * English speaking adults age ≥18 years * Patients with an established diagnosis of (1) bipolar I disorder, (2) bipolar II disorder, (3) schizophrenia, (4) schizoaffective disorder, or (5) schizophreniform disorder * Judged to be clinically agitated at the time of Screening and Baseline with a AMSS ≥2 * Able to read, understand, and provide written informed consent * Subject judged to be likely capable of self-administration of BXCL501 sublingually or buccally Exclusion Criteria: * Likely to be discharged, admitted, or transferred from the ED within 6 hours after study medication administration * Administration of benzodiazepines or antipsychotic drugs in the 2 hours before study treatment * Treatment with alpha-1 noradrenergic antagonists * Female patients who are pregnant or are breastfeeding * Hypotension (systolic blood pressure \<100 mmHg or diastolic blood pressure \<60 mmHg) and/or bradycardia (heart rate \<55 beats per minute) at the time of Screening or Baseline evaluation * History of dysautonomia * Patient with a known diagnosis of familial long QT syndrome, second degree or third degree atrioventricular block without pacemaker, or sick sinus syndrome * Patients with serious or unstable medical illnesses determined by the study investigators or qualified designees * Patients with history of allergic reactions to dexmedetomidine * Patients previously enrolled and completed the current study * Patients actively enrolled in other ED-based studies involving pharmacological or behavioral interventions