Tue16November0750PM 9

A 16-year-old female is admitted with a severe paracetamol overdose. She is treated with IV N-acetylcysteine (NAC).

By replenishing which of the following compounds does N-acetylcysteine function as an antidote in paracetamol overdose?

(Please select 1 option)

Methionine

Cystine

Cysteine

Glutathione Correct

Arginine

Explanation

Paracetamol is predominantly metabolised to glucuronide and sulphate conjugates, which are excreted in the urine.

Hepatotoxicity is related to the conversion of a small proportion of the ingested dose to N-acetyl-p-benzoquinoneimine.

In therapeutic doses N-acetyl-p-benzoquinoneimine is detoxified by conjugation with glutathione in the liver, but once the protective intracellular glutathione stores are depleted hepatic and renal damage may ensue.

NAC and methionine replenishes glutathione stores in the liver and may also act through its sulphhydryl (-SH) group as a direct reducing agent.

Reference:

Alsalim W, Fadel M. Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Oral methionine compared with intravenous n-acetyl cysteine for paracetamol overdose. Emerg Med J. 2003;20:366-7.

Patient.info. Paracetamol Poisoning.

Answer Statistics

1

2%

2

1%

3

98%

4

1%

Times answered: 270