Clinical scenario

A 19 year old woman brought to the emergency department six hours after paracetamol overdose. She is fully conscious and admits ingestion of 32 tablets of paracetamol. She is complaining of abdominal discomfort but no nausea or vomiting. Her examination is unremarkable. You arranged blood investigations. Intravenous access and n-acetyl cysteine infusion started as per protocol. You wonder whether oral methionine would have been as effective as n-acetyl cysteine in her treatment.

Three part question

In a [patient with paracetamol overdose within eight hours] is [methionine as good as or better than n-acetyl cysteine] at [reducing liver damage]?

Search strategy

Medline 1966–04/03 using the OVID interface. [exp methionine OR methionine$.mp] AND [exp acetaminophen OR acetaminophen$.mp OR paracetamol.mp] AND [exp acetylcysteine OR acetylcysteine$.mp OR parvolex.mp] LIMIT to human AND English.

Search outcome

Altogether 39 papers were found, of which two were relevant (table 5).

Comment(s)

There have been no randomised controlled trials and only two prospective observational studies comparing these two drugs. However, patients in these two studies had the antidote within eight hours.

CLINICAL BOTTOM LINE

Intravenous acetylcysteine (parvolex) is more effective than methionine at preventing liver damage in patients after paracetamol overdose.