Antidotal treatment of antimuscarinic delirium (AMD) standardly involves parenteral administration of physostigmine. However, due to cessation of physostigmine production, administration of oral or transdermal rivastigmine may serve as a suitable alternative. A pediatric case of diphenhydramine-induced AMD who was successfully treated with transdermal rivastigmine is presented. A 15-year-old, 47 kg girl without medical history presented to the emergency department after intentionally ingesting approximately 2.5 grams of diphenhydramine the evening prior. The patient was delirious and quickly transferred to a pediatric intensive care unit (PICU). On admission, the patient was exhibiting AMD. An electrocardiogram demonstrated sinus tachycardia, with a QRS of 78 msec and a QTc interval of 453 msec. Serum acetaminophen, salicylate, ethanol levels, and routine chemistries were unremarkable. Transdermal rivastigmine 0.2 mg/kg/24 hours was administered three hours after PICU arrival in the nearest available patch dose, 9.5mg/24 hours. Six hours after initiating rivastigmine, she was fully oriented, and AMD resolved. The rivastigmine patch was removed after 24 hours without recurrence of delirium. The patient had no adverse effects from the rivastigmine patch and was transferred in normal condition on hospital day four for psychiatric admission. In this single pediatric patient, transdermal rivastigmine was a safe, effective, long-acting treatment for AMD without significant side effects. Further study is required, especially regarding pediatric dosing and the role of combined oral and transdermal formulations. This case is unique, with no prior reports on transdermal rivastigmine for pediatric AMD.
Druetto et al. (Sun,) studied this question.