UMEM Educational Pearls

Title: Benefit of activated charcoal in large acetaminophen ( >= 40 gm) overdose.

Keywords: activated charcoal, large acetaminophen overdose, NAC dose (PubMed Search)

Posted: 1/11/2018 by Hong Kim, MD, MPH (Updated: 4/23/2024)
Click here to contact Hong Kim, MD, MPH

Acetaminophen (APAP) overdose is the leading cause of liver failure in the U.S. and Europe. Large APAP ingestion can result in hepatotoxicity despite the early initiation of n-acetylcysteine (NAC).

A recently published study from Austrialia investigated the effect of activate charcoal and increasing the NAC dose for large APAP overdose patients (3rd bag: 100 to 200 mg/kg over 16 hours) during first 21 hours of NAC therapy

acetaminophen ratio (first APAP level taken between 4 to 16 hour post ingestion / APAP level on the Rumack nomogram line at that time point) was determined to compare APAP levels at different time points among study sample

e.g.

first APAP level at 4 hour post ingestion = 400

APAP level on the Rumack APAP nomogram at 4 hour post ingestion = 150

APAP ratio = 400/150 = 2.67

Findings:

Activated charcoal (AC): if given within 4 hours, AC significantly decreased the APAP ratio (OR: 1.4 vs. 2.2)
Increased dose of NAC during the first 21 hour significantly decreased the risk of hepatotoxicity (OR: 0.27; 95% CI: 0.08 - 0.94).

Conclusion:

Administration of AC in patients with history of large APAP overdose (>=40 gm) within 4 hour of ingestion can still be beneficial.
Increasing NAC dosing (3rd bag in first 21 hour thearpy) may decrease the risk of hepatotoxicity.

Note: Any increase in NAC dosing from the standard 21 hour therapy should be performed after consulting your regional poison center.

References

Chiew AL et al. Massive paracetamol overdose: an obsevational study of the effect of activated charcoal and increased acetylcysteine dose (ATOM-2). Clin Toxicol 2017;55:1055-1065. PMID: 28644687.