12th March 2024

Paracetamol poisoning

Paracetamol is the most frequently involved drug in intentional overdoses. Toxicity occurs when a dose of 75mg/kg or more is consumed within a 24-hour period. The presentation can vary, with many being asymptomatic and others experiencing nausea, vomiting or abdominal pain. A build-up of the toxic metabolite N-acetyl- p-benzoquinone imine (NAPQI) can result in acute liver injury which, in turn, can lead to fulminant hepatic failure within 24-36 hours. Less commonly, it can cause nephrotoxicity and renal tubular necrosis. If a paracetamol overdose is suspected, then LFTs and INR should be measured, and a paracetamol nomogram should be used to guide management. Acute ethanol intake alongside paracetamol intake is a protective factor for paracetamol toxicity as it inhibits microsomal acetaminophen oxidation leading to reduced levels of NAPQI.

Acetylcysteine is the mainstay of treatment when hepatocellular toxicity is suspected. This agent increases glutathione synthesis which inactivates NAPQI. A liver transplant is indicated if any of the following criteria are met.