What is the treatment for acetaminophen (Tylenol) overdose in pediatric patients?

Treatment of Acetaminophen Overdose in Pediatric Patients

N-acetylcysteine (NAC) is the definitive treatment for acetaminophen overdose in pediatric patients and should be administered as soon as possible, ideally within 8-10 hours of ingestion, to reduce the risk of hepatotoxicity, liver failure, and mortality. 1, 2

Risk Assessment and Indications for Treatment

• Use the Rumack-Matthew nomogram to stratify risk for patients with:

  • Single acute ingestion
  • Known time of ingestion
  • Presentation within 24 hours of ingestion
  • Serum acetaminophen level drawn at least 4 hours post-ingestion

• NAC is indicated for:

  • Patients with acetaminophen levels in the "possible risk" or "probable risk" zones on the nomogram 1
  • Patients who cannot be risk-stratified using the nomogram (delayed presentation >24 hours, unknown time of ingestion, extended-release preparations) 2
  • Patients with repeated supratherapeutic ingestions (>200 mg/kg or 10g in 24 hours, whichever is less) 1
  • Any patient with evidence of hepatotoxicity (elevated transaminases) thought to be due to acetaminophen 1
  • Patients with hepatic failure due to acetaminophen 1

NAC Administration Protocols

Intravenous NAC Protocol

1. Loading dose: 150 mg/kg diluted in appropriate fluid over 15-60 minutes
2. First maintenance dose: 50 mg/kg over 4 hours
3. Second maintenance dose: 100 mg/kg over 16 hours 2, 3

Alternative two-bag regimen (associated with fewer medication errors and cutaneous reactions in pediatric patients):

1. Loading dose: 150 mg/kg over 1 hour
2. Maintenance infusion: 10-15 mg/kg/hr for 20 hours 4, 5

Oral NAC Protocol

1. Loading dose: 140 mg/kg
2. Maintenance doses: 70 mg/kg every 4 hours for 17 doses 2

For patients presenting within 4 hours of ingestion, activated charcoal should be administered before starting NAC 2.

Fluid Considerations for Pediatric Patients

• To prevent hyponatremia in pediatric patients, use 0.45% saline with 5% dextrose as the diluent for NAC rather than just 5% dextrose 6

Duration of Treatment

• Standard duration: 21 hours for IV protocol or 72 hours for oral protocol
• Treatment may be discontinued earlier if:
  • Acetaminophen levels are undetectable
  • Liver enzymes are normal or trending downward
  • Patient shows no signs of hepatotoxicity 7, 5

Monitoring During Treatment

• Serial acetaminophen levels
• Liver function tests (AST, ALT)
• Renal function tests
• Coagulation studies
• Monitor for adverse reactions to NAC:
  • Oral: nausea, vomiting (common)
  • IV: anaphylactoid reactions (rash, urticaria, bronchospasm) - treat with antihistamines and slow infusion rate 2

Special Considerations

• For patients with evidence of hepatic failure, IV NAC is preferred over oral administration 2
• Early initiation of NAC is critical - efficacy decreases significantly when started >10 hours post-ingestion 1
• Even with delayed presentation (>24 hours), NAC should still be administered if acetaminophen toxicity is suspected 8
• Pediatric patients receiving NAC have shown better outcomes than those not receiving NAC, with no reported deaths in treated pediatric patients 3

Pitfalls and Caveats

• Do not delay NAC administration while waiting for acetaminophen levels if there is strong suspicion of toxic ingestion
• Do not rely on normal initial liver enzymes to exclude toxicity, as hepatotoxicity may develop hours to days after ingestion
• Repeated supratherapeutic ingestions may have worse outcomes than single acute overdoses and require a higher index of suspicion 1
• Medication errors are common with the traditional three-bag regimen; two-bag regimens may reduce this risk in pediatric patients 4, 5
• Remember that the nomogram cannot be used for extended-release preparations, repeated ingestions, or unknown time of ingestion