haloperidol

Haloperidol is a butyrophenone-class typical antipsychotic that primarily works by blocking dopamine D2 receptors in the mesolimbic, mesocortical, nigrostriatal, and tuberoinfundibular pathways. Its high potency means effective antipsychotic action at low doses (0.5-20mg daily), but this correlates with increased extrapyramidal side effects (EPS) including acute dystonia, parkinsonism, akathisia, and tardive dyskinesia. The drug has minimal anticholinergic, antihistaminergic, and alpha-adrenergic blocking activity compared to low-potency antipsychotics like chlorpromazine. Haloperidol is highly effective for positive symptoms (hallucinations, delusions) but poor for negative symptoms of schizophrenia. It's commonly used in emergency settings for acute agitation and psychosis. The drug undergoes hepatic metabolism via CYP3A4 and has a long half-life (12-38 hours). Notable adverse effects include QT prolongation (especially with IV administration), hyperprolactinemia, and neuroleptic malignant syndrome (rare but potentially fatal). It's available in oral, IM, and long-acting depot formulations.