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Acute psychosis, although not recognized as a diagnostic term in DSM-5 is commonly used to describe a rapid deterioration of behavior associated with hallucinations and delusions. Schizophreniform disorder, brief psychotic disorder, and organic psychoses fall under this rubric. The DSM-5 diagnosis of schizophreniform disorder depends on the persistence of schizophrenia-like symptoms for at least 1 month and exclusion of other causes of acute psychosis. Brief psychotic disorder (often referred to as brief reactive psychosis) lasts less than 1 month, but more than 1 day. It is typically regarded as a reaction to marked stress in persons with borderline or antisocial personality disorders.
Haloperidol is a typical butyrophenone type antipsychotic that exhibits high affinity dopamine D 2 receptor antagonism and slow receptor dissociation kinetics.  It has effects similar to the phenothiazines .  The drug binds preferentially to D 2 and α 1 receptors at low dose (ED 50 = and mg/kg, respectively), and 5-HT 2 receptors at a higher dose (ED 50 = mg/kg). Given that antagonism of D 2 receptors is more beneficial on the positive symptoms of schizophrenia and antagonism of 5-HT 2 receptors on the negative symptoms, this characteristic underlies haloperidol's greater effect on delusions, hallucinations and other manifestations of psychosis.  Haloperidol's negligible affinity for histamine H 1 receptors and muscarinic M 1 acetylcholine receptors yields an antipsychotic with a lower incidence of sedation, weight gain, and orthostatic hypotension though having higher rates of treatment emergent extrapyramidal symptoms .