P2.D062: Oral N-Acetylcysteine Use for Acetaminophen Toxicity in an Infant

Introduction: The unintentional ingestion of acetaminophen is among the most common reasons for visits to the pediatric emergency department. A specific antidote, N-Acetylcysteine (NAC), is available in equally effective oral or intravenous formulations. We describe the use of oral NAC in an infant with a potentially toxic overdose of acetaminophen.

Case Description: A 4.5 kg 2-month-old, full-term infant presented to the hospital after an unintentional acetaminophen overdose. Patient received a total of 90 mL of acetaminophen (160 mg/5mL) over a 24-hour period with doses of 30 mL administered 8-9 hours apart. The total dose administered was 2,880 mg (640 mg/kg) of acetaminophen. There was no concern for any co-ingestion. At time of presentation, patient was well-appearing with baseline activity level and feeding normally. Approximately 8 hours after the last dose, acetaminophen level was 189.3 mcg/mL and complete metabolic panel showed no abnormalities in liver enzymes (ALT/AST). Patient was started on a one time dose of intravenous NAC in the Emergency Department and Poison Control was contacted. Subsequently, toxicologists recommended the initiation of enteral NAC therapy, 70 mg/kg every 4 hours for a 24-hour period, after which time further treatment needs would be reevaluated. Each dose was administered over 30 minutes via nasogastric tube to reduce the risk of emesis. Twenty hours after starting NAC therapy, patient’s ALT and AST were elevated to 166 U/L and 217 U/L, respectively; acetaminophen level was undetectable. Due to this elevation in ALT/AST, patient continued to receive N-acetylcysteine every 4 hours while monitoring his liver enzymes every 8 hours. Through the hospital course, patient’s liver enzymes trended down with continued treatment. Coagulation studies remained within normal limits throughout clinical course. In total, patient received 15 doses (70 mg/kg) of NAC over 60 hours. He tolerated the therapy well with no hemodynamic instability or adverse effects during treatment.

Discussion: Acetaminophen toxicity is often treated with the intravenous form of NAC. However, certain cases may warrant the consideration of oral NAC. In the infant population, complications with intravenous NAC can include fluid overload and hyponatremia. In our case, the safety profile of oral NAC was thought to be more favorable than intravenous NAC which is one of the main reasons it was utilized. This highlights the benefit of oral NAC in appropriate situations.

Conclusion: Oral NAC is a safe and effective means to treat acetaminophen toxicity in pediatric patients in many cases. Oral therapy should be considered in cases where a patient may be at higher risk of complications of IV therapy such as hyponatremia or volume overload. This case demonstrates a positive outcome with oral NAC therapy and no adverse effects from treatment. Poison Centers can help guide treatment in rare but serious poisoning such as this.