Acetaminophen overdose resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vidit Bhargava, M.B.B.S [2]

Definition

Acetaminophen overdose/toxicity occurs when there is intentional, accidental, acute and/or chronic ingestion of supratherapeutic doses of acetaminophen (paracetamol). It is the most widely used OTC (over the counter) analgesic in USA. It is available in the U.S market under the following brand names.

Tylenol
Anacin-3
Liquiprin
Percocet
Tempra
Cold and flu medicines
Aceta
Actimin
Apacet>br> Aspirin Free Anacin
Atasol
Banesin
Dapa
Datril Extra-Strength
Feverall
Fibi
Genapap
Genebs

Panadol

Common dosage forms and strengths

1. Suppository: 120 mg, 125 mg, 325 mg, 650 mg
2. Chewable tablets: 80 mg
3. Regular strength: 325 mg
4. Extra strength: 500 mg
5. Liquid: 160 mg/teaspoon
6. Drops: 100 mg / mL, 120 mg / 2.5 mL

Toxic Dose

The toxic dose of paracetamol is highly variable. In individuals over 6 years of age, single doses above 200 mg/kg consumed over a single 24-hour period have a reasonable likelihood of causing toxicity. If an individual has consumed large quantities of paracetamol over a 48 hour period, a dose of above 6 grams or 150 mg/kg in the subsequent 24 hour period may cause toxicity.

Management

Shown below is an algorithm summarizing the approach to Acetaminophen Overdose.

Take focused history: ❑ Time since last ingestion ❑ Number of tablets/other dosing form taken ❑ Frequency of dosage

Characterize the symptoms & examine the patient: Stage I: First 24 hours ❑ Asymptomatic ❑ Nausea & vomiting ❑ Diaphoresis ❑ Anion gap metabolic acidosis & coma (with massive doses) Stage II: 24 to 72 hours Clinical & lab features of hepatotoxicity ❑ Right upper quadrant tenderness ❑ Deranged LFT's, PT, Serum bilirubin Clinical & lab features of nephrotoxicity ❑ Oligouria, hematuria ❑ Deranged RFT's, proteinuria, hematuria, casts Stage III: 72 to 96 hours Signs of liver failure ❑ Hepatic tenderness ❑ Jaundice ❑ Impaired consciousness ❑ Asterixis ❑ Foetur hepaticus ❑ Haemorrhage Labs consistent with severe liver failure ❑ AST/ALT levels > 1000 mg/Dl ❑ Prolonged PT/INR ❑ Hypogycemia ❑ Lactic ❑ Total bilirubin > 4.0 ❑ Renal failure ❑ Death from multiorgan system failure Stage IV: 4 days to 2 weeks ❑ Recovery

References

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