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Oral methionine compared with intravenous n-acetyl cysteine for paracetamol overdose
  1. Walid Alsalim, Specialist Registrar,
  2. Mohamed Fadel, Specialist Registrar
  1. Department of Emergency Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK;


    A short cut review was carried out to establish whether methionine was better than n-acetyl cysteine at reducing the severity of liver damage after paracetamol overdose. Thirty nine papers were found using the reported search, of which two presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. A clinical bottom line is stated.

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    Report by Walid Alsalim,Specialist RegistrarChecked by Mohamed Fadel, Specialist Registrar

    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] AND [exp acetylcysteine OR acetylcysteine$.mp OR] LIMIT to human AND English.

    Search outcome

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

    Table 5


    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.


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

    Report by Walid Alsalim,Specialist RegistrarChecked by Mohamed Fadel, Specialist Registrar