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KembaraXtra-Emergency and Acute Medicine - Neuroleptic Poisoning
Neuroleptic poisoning refers to toxicity from antipsychotic medications used to treat psychotic disorders, agitation, dementia, autism-related behavioral problems, eating disorders, migraines, and as antiemetics. In acute overdose, symptoms are usually mild to moderate, with central nervous system and cardiovascular effects predominating, though severe toxicity with seizures, coma, or life-threatening complications may occur. Symptom onset is typically within 6 hours but may be delayed up to 24 hours with extended-release preparations such as paliperidone or with agents like aripiprazole.
Typical neuroleptics such as haloperidol, chlorpromazine, prochlorperazine, and droperidol strongly antagonize dopamine receptors and also block histamine, muscarinic, and alpha-adrenergic receptors, contributing to sedation, hypotension, and anticholinergic effects. Atypical neuroleptics including risperidone, olanzapine, quetiapine, clozapine, and ziprasidone have weaker dopamine antagonism with additional serotonergic effects, generally causing less extrapyramidal toxicity but still capable of serious overdose effects.
Clinical manifestations range from mild sedation to coma, with possible anticholinergic delirium, seizures, dystonia, and akathisia. Cardiovascular findings include tachycardia, hypotension, QT prolongation, and rarely torsades de pointes. Respiratory depression and loss of airway reflexes may occur. Dystonic reactions are the most common adverse effect, presenting with involuntary spasms of the face, neck, back, or limbs; rare laryngeal dystonia may cause stridor and respiratory distress. Neuroleptic malignant syndrome is an uncommon but life-threatening complication marked by hyperthermia, rigidity, altered mental status, autonomic instability, rhabdomyolysis, and renal failure. Clozapine and olanzapine may cause agranulocytosis, and several neuroleptics are associated with hyperglycemia and new-onset diabetes.
Evaluation includes continuous monitoring of vital signs, cardiac rhythm, oxygen saturation, and core temperature. Laboratory studies should assess electrolytes, renal function, glucose, liver enzymes, creatine kinase when neuroleptic malignant syndrome or agitation is suspected, and complete blood count in clozapine exposure. An electrocardiogram is essential to evaluate QT or QRS prolongation.
Management is primarily supportive, with early attention to airway, breathing, and circulation. Supplemental oxygen, intravenous access, glucose assessment, and intubation for respiratory compromise are critical. Activated charcoal may be given within one hour of ingestion if the airway is protected. Hypotension is treated with intravenous fluids and vasopressors such as norepinephrine if refractory. Dystonic reactions respond rapidly to diphenhydramine or benztropine, continued for several days to prevent recurrence. Seizures are treated with benzodiazepines, with phenobarbital for refractory cases. Suspected neuroleptic malignant syndrome requires immediate discontinuation of the offending agent, aggressive cooling, benzodiazepines, intravenous fluids, and consideration of bromocriptine or dantrolene in severe cases.
Patients with significant symptoms, abnormal vital signs, central nervous system depression, dysrhythmias, or suspected neuroleptic malignant syndrome require admission, often to an intensive care unit. Asymptomatic patients may be discharged after adequate observation, with longer monitoring for delayed-onset agents or extended-release formulations. Intentional overdoses require psychiatric evaluation, while accidental exposures warrant poison prevention counseling.
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