P3.213: Patching Up the Confusion: Rare Use of Rivastigmine Patch for Oxybutynin Overdose in a Pediatric Patient

Introduction: Many commonly used medications possess anticholinergic properties and, when used in excess, can induce severe side effects. Management of anticholinergic toxicity ranges from supportive care to administration of an antidote for severe central nervous system (CNS) toxicity. The evidence-based agent of choice is physostigmine. Shortage in physostigmine has necessitated trialing alternative cholinesterase inhibitors such as rivastigmine. Rivastigmine, available in oral and transdermal forms, is approved for managing dementia in Alzheimer’s disease and Parkinson’s disease. As such, rivastigmine is primarily used in the geriatric population. We present a unique case of anticholinergic overdose in a pediatric patient effectively treated with rivastigmine patch.

Case Description: A 13-year-old male with spina bifida with tethered cord syndrome status post repair presented with strange behavior. He had intermittent staring episodes, unsteady gait, and spoke nonsensically about mice.

He was awake, lethargic, and disoriented with equal minimally reactive pupils (8mm), dry mucous membranes, and tachycardia to 153 beats per minute (bpm). He spoke in one-word phrases but didn’t respond appropriately or follow commands. He reached for imperceptible objects with outbursts of laughter. He also had episodes of urinary incontinence with high post-void residuals, requiring foley placement. Labs were notable for alanine transaminase 62 U/L, aspartate transaminase 58 U/L, and alkaline phosphatase 414 U/L. Urine drug screen was negative. Electrocardiogram showed sinus tachycardia (144 bpm) with normal intervals. Computed tomography of the head without contrast was negative.

The patient’s family discovered a suicide note along with videos of him ingesting about fifty 10mg tablets of oxybutynin extended release.

Medical toxicology recommended physostigmine which was not accessible due to national shortages. Rivastigmine was available, but the patient was unable to take oral medication, and the tablets could not be crushed for gavage. To prevent treatment delay, a rivastigmine transdermal patch 9.5mg/24 hour was applied.

The patient’s symptoms and mental status gradually resolved with rivastigmine transdermally. He was discharged home on hospital day six in stable condition at baseline after psychiatric clearance.

Discussion: There is a paucity of case reports that demonstrate rivastigmine as an antidote for anticholinergic toxicity, and majority feature adults. In situations where the antidote of choice, physostigmine, is unavailable, rivastigmine should be considered to prevent treatment delay. The transdermal patch makes for a convenient method of treatment especially in those who cannot tolerate oral medications and where bioavailability may vary with oral agents in the setting of decreased gastrointestinal motility with anticholinergic poisoning.

Conclusion: This is one of few reported cases demonstrating effective use of transdermal rivastigmine to manage anticholinergic poisoning in a pediatric patient. Transdermal rivastigmine patch should be explored as an option for reversal of anticholinergic toxicity in pediatric patients, especially those where oral administration is not feasible and where physostigmine is unavailable.