Are Phenothiazines for Sedation in Children Worth the Risk?

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Overdosing a Serious Issue

With any sedative, there is the potential for poisoning by iatrogenic errors in a hospital setting or unintentionally or intentionally in a home setting.[1] NMS, dystonic reactions and oculogyric crisis can all be caused by phenothiazine overdose. The American Association of Poison Control Centers reported 11 065 toxic exposures to phenothiazine sedatives in 1997; 3587 of exposures were in patients aged <19 years.[10]

In general, a triad of coma, prolonged QTc interval and pupillary meiosis is indicative of suspected phenothiazine overdose.[1] Severe extrapyramidal reactions are also commonly seen. Diagnosis is often made in patients presenting with symptoms referrable to the neurological system with a known history of phenothiazine consumption. Dystonia in patients who are hospitalised or being treated by different specialists may be suggestive of therapeutic misadventure.[1]

There is no specific antidote available for phenothiazine intoxication. However, anticholinergic agents may be useful for control of extrapyramidal reactionsassociated with overdosage.[5]

In the patient presenting with unknown poisoning but symptoms of dystonia or oculogyric crisis, diphenhydramine, benzatropine or trihexyphenidyl may be administered to aid in confirming the diagnosis of poisoning with phenothiazines.[1]

Activated charcoal is also useful is cases of phenothiazine overdose because charcoal binds to all phenothiazine compounds, ensuring the complex drug is eliminated in the stool and not in the blood stream.[1] Dantrolene should be administered to those with NMS symptoms and intensive supportive measures should be initiated.


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