NUBE 2024

Acetaminophen overdose is a potentially fatal clinical syndrome, warranting prompt and accurate assessment and clinical care. Acetaminophen toxicity can occur from acute ingestion, or chronic use over time. Though this talk focuses on acute hepatic consequences of overdose, inadvertent exposure over time often has a worse prognosis due to later recognition and treatment. The acute toxidrome has 4 stages, whereby stage 2 is what appears to be a resolving syndrome. However, if unrecognized, this may progress to severe hepatotoxicity and death. An Acetaminophen level 4 hours after the overdose that is greater than 150 mcg/mL warrants urgent initiation of the antidote N-Acetylcysteine and inpatient hospitalization.

Acetaminophen pharmacology is critical to treatment. Toxicity occurs when the body's innate metabolic pathways are saturated, causing build-up of a toxic metabolite which binds to hepatocytes, leading to liver injury and fatality. N-Acetylcysteine treatment enhances the clearance of the toxic metabolite, and should be promptly started. There are specific protocols for oral and for IV management. Astute and correct treatment has high success rates, though serious complications may result. In cases where Acute Liver Failure occurs, there is a high mortality rate, and 1/3 of patients will require a liver transplant. Fortunately, if N-Acetylcysteine is given within 8-10 hours after the overdose, serious hepatotoxicity is uncommon and death is extremely rare, regardless of the initial serum concentration.

Learning Objectives:

An appreciation of the emergent nature of Acetaminophen overdose.

Using the serum Acetaminophen level to decide when to treat.

Proper use of the antidote N-Acetylcysteine.