Management overview for modified-release paracetamol poisoning

For paracetamol poisoning presenting in primary care, see Paracetamol poisoning: advice for primary care providers.

This monograph discusses management of acute ingestions of modified-release paracetamol tablets. Other scenarios covered in different monographs include:

Paracetamol is widely available and responsible for a large proportion of accidental and deliberate cases of poisoning. Paracetamol poisoning is common, but rarely causes severe liver injury or death. Poisoning caused by modified-release paracetamol is associated with a higher risk of acute liver injury1 than immediate-release preparations, irrespective of treatment. Observational studies of modified-release paracetamol poisoning found that many patients had persistently raised serum paracetamol concentrations and needed prolonged acetylcysteine treatment; some patients developed acute liver injury despite prompt acetylcysteine treatment.

Modified-release paracetamol is available in 665 mg tablets, each containing 69% modified-release and 31% immediate-release paracetamol. If a patient has taken a mixture of immediate-release and modified-release paracetamol, treat as for poisoning caused by modified-release paracetamol.

Note: Treat patients who have taken a mixture of immediate-release and modified-release paracetamol as for poisoning caused by modified-release paracetamol.

Refer patients with suspected deliberate paracetamol poisoning to hospital for assessment, regardless of the dose ingested. The hospital must be able to measure liver biochemistry and serum paracetamol concentration urgently. For advice on the management of acute paracetamol poisoning presenting to rural and remote facilities lacking pathology services, refer to the 2019 Australian and New Zealand guidelines for the management of paracetamol poisoning2.

Treatment algorithms for modified-release paracetamol poisoning are based on guidelines for immediate-release paracetamol poisoning. However, the pharmacokinetics of modified-release paracetamol after deliberate self-poisoning have not been well defined. Serial serum paracetamol concentration measurements are important to check for ongoing paracetamol absorption.

Treatment for modified-release paracetamol poisoning may involve gastrointestinal decontamination with activated charcoal, and the antidote, acetylcysteine3.

1 Liver injury has various definitions; the Toxicology and Toxinology Expert Group uses a definition of a serum alanine aminotransferase (ALT) concentration of 50 U/L or higher.Return
2 Chiew AL, Reith D, Pomerleau A, Wong A, Isoardi KZ, Soderstrom J, et al. Updated guidelines for the management of paracetamol poisoning in Australia and New Zealand. Med J Aust 2019. [URL] Return
3 Acetylcysteine is also commonly known as N-acetylcysteine, and the abbreviation ‘NAC’ is used in many texts and local protocols.Return