(657) Repeated Hemodialysis After Extended-Release Acetaminophen Ingestion

Introduction: The annual number of acetaminophen overdoses among youths has doubled recently, to more than 20,000 cases 2021 and 2022 (Farah et al, 2023). Acetaminophen toxicity results from the production of the metabolite NAPQI and early detoxification with N-acetylcysteine (NAC) is the mainstay of therapy. Rarely, adjunctive therapies including hemodialysis (HD) and fomepizole are employed. We present a patient who received two separate HD runs greater than 24 hours apart after a single, massive ingestion of extended-release (ER) acetaminophen.

Description: A 15 year-old male presented 2 hours after reportedly ingesting ~195g of ER acetaminophen. Despite receiving charcoal treatment and starting NAC, his drug level increased to >400mg/L, lactate rose to 5.6 mmol/L, and mental status declined. He was intubated, his NAC dose was doubled, fomepizole was given, and HD was urgently initiated. His drug level decreased (193mg/L) and mental status improved after 4 hours of HD. Given lack of acidosis or transaminitis, he was extubated. A day later, his drug level again increased substantially (347 mg/L), transaminitis worsened (ALT 5,138 U/L), and INR rose (2.9). His NAC dose was doubled again and fomepizole was re-administered. Given concern for ongoing drug absorption, a CT scan was performed which was negative for bezoar formation. HD was restarted with rapid improvement in his drug level. His transaminases began to fall, his INR normalized, and NAC was stopped.

Discussion: Intermittent HD and fomepizole are more frequently being used to treat acetaminophen ingestion (Woolum et al, 2020, Chiu et al, 2021). Interestingly, this patient’s drug level rose more than 24 hours after the initial HD run. Given the efficiency with which HD clears the drug, it appears that the patient’s absorption was ongoing after the first HD was stopped, which likely was due to the ingestion of an ER product. A bezoar does not to appear to have slowed transit of ingested drug in light of his negative CT. Given the growing number of available extended-release formulations, and the possibility of co-ingestions of medications that slow gastric motility (eg., antihistamines), we recommend close vigilance of both drug levels and markers of liver function prior to removal of dialysis catheters as subsequent HD may be warranted.