Background: Anticholinergic toxicity is commonly encountered in the emergency department. However, the availability of physostigmine, a central acetylcholinesterase inhibitor used to reverse anticholinergic delirium, has been significantly limited due to national drug shortages in the United States. Several articles have explored the viability of rivastigmine as an alternative treatment in these patients.
Case report: A 33-year-old man presented to the emergency department after a suspected suicide attempt. The patient was found with an empty bottle of diphenhydramine at the scene. On arrival, he was tachycardic and delirious, with dilated and nonreactive pupils and dry skin. As the clinical picture was highly suggestive of anticholinergic toxicity, the patient was treated with oral rivastigmine at a starting dose of 4.5 mg to reverse his anticholinergic delirium. Although a repeat dose was required, his delirium resolved without recurrence. Why Should an Emergency Physician Be Aware of This? Oral rivastigmine has been applied successfully here and in other case reports to reverse anticholinergic delirium with the benefit of prolonged agitation control. Emergency physicians may consider this medication in consultation with a specialist, with initial doses starting at 4.5-6 mg, if encountering anticholinergic delirium when physostigmine is not available.
Keywords: anticholinergic delirium; anticholinergic toxicity; diphenhydramine; physostigmine; rivastigmine.
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