This pilot study will enroll 30 male and female adults with primary psychiatric complaint and a documented diagnosis of bipolar I disorder, bipolar II disorder, schizophrenia, schizoaffective disorder, or schizophreniform disorder, presenting to the emergency department with clinical signs of acute agitation. Eligible subjects will receive an initial dose of BXCL501 (180mcg) and a repeat dose (90mcg) 2 hours after the first BXCL501 dose in the event of persistent or recurrent agitation (up to two repeat doses) while under medical supervision in the emergency department. Efficacy and safety assessments will be conducted periodically before and after dosing.