What are the treatment and management steps for an 18-month-old child who has ingested 200 mg of lamotrigine (anticonvulsant medication)?

Management of 200 mg Lamotrigine Ingestion in an 18-Month-Old Child

Immediate decontamination and supportive care are essential for managing this potentially life-threatening lamotrigine overdose in an 18-month-old child, as ingestions of ≥525 mg have been associated with severe CNS depression and seizures in young children.

Initial Assessment and Stabilization

• Assess and secure airway, breathing, and circulation (ABCs) as the first priority 1
• Obtain IV access immediately for administration of fluids and medications 1
• Monitor vital signs continuously, with particular attention to cardiac monitoring due to risk of conduction abnormalities 2

Decontamination

• Administer activated charcoal 1-2 g/kg via nasogastric tube if the child presents within 1-2 hours of ingestion and has intact airway protective reflexes 1
• Non-sorbitol containing activated charcoal preparations should be used for children under 1 year old 1
• If airway protective reflexes are impaired, the risk of administering activated charcoal may outweigh the benefits 1

Specific Toxicity Management

Neurological Complications

• Seizures are a common complication in lamotrigine overdose, especially in children ≤3.5 years old 2
• For seizure management:
  • Administer lorazepam 0.05-0.1 mg/kg IV (maximum: 4 mg per dose) for acute seizures 1
  • May repeat lorazepam dose every 10-15 minutes if needed for continued seizures 1
  • Be prepared to provide respiratory support as benzodiazepines can cause respiratory depression 1
  • Follow with a long-acting anticonvulsant if seizures persist 1

Cardiovascular Complications

• Monitor for cardiac conduction abnormalities including QRS prolongation, QT prolongation, and heart block 3, 2
• If conduction abnormalities develop:
  • Consider sodium bicarbonate administration, although evidence for efficacy is limited 2
  • Monitor for hypotension and treat with isotonic IV fluids 1
  • Be prepared for possible cardiac arrest, as this has been reported with lamotrigine overdose 3

Laboratory Monitoring

• Obtain baseline complete blood count, electrolytes, renal and liver function tests 2
• Consider measuring serum lamotrigine concentration if available (levels >3.8 mg/L have been associated with seizures in pediatric patients) 2
• Monitor electrolytes, particularly potassium, as hypokalemia has been reported 4

Supportive Care

• Provide isotonic intravenous fluids for hydration and to maintain hemodynamic stability 1
• For respiratory depression, provide supplemental oxygen and be prepared for endotracheal intubation if necessary 5
• Monitor for rhabdomyolysis, especially if seizures occur 4

Disposition

• Admit to pediatric intensive care unit for close monitoring, as lamotrigine overdose can cause delayed toxicity 2
• Continue cardiac monitoring for at least 24 hours after ingestion 2
• Consider consultation with a regional poison control center for additional guidance 1

Prognosis

• While most lamotrigine exposures result in mild or no toxicity, children appear more susceptible to CNS toxicity than adults 2
• The 18-month-old age of this patient is a significant risk factor, as all reported cases of seizures in pediatric lamotrigine overdose occurred in children ≤3.5 years old 2
• Vigilant monitoring and prompt intervention for complications are critical for a favorable outcome 5