The Pharmaceutical Journal
Vol 279 No 7464 p157-158
11 August 2007

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A better acetylcysteine prescription

Uttamlal M. Chouhan, Elisabeth J. Dubourg and Linda Dodd discuss the complicated regimen of acetylcysteine administration in paracetamol overdose and how two prescribing aids can reduce the likelihood of both prescribing and administration errors

SUMMARY

It is estimated that there are about 70,000 cases of paracetamol overdose in Britain each year.

Deaths resulting from paracetamol overdose have been falling since the restriction of sales of larger tablet pack sizes in 1998 but, in England and Wales, there are still around 100 deaths every year resulting from the ingestion of paracetamol alone or paracetamol-containing preparations.

Since 1981 the BNF has recommended acetylcysteine as the treatment of choice in the UK for the management of paracetamol overdose. It is be administered as an intravenous infusion as follows:

• First dose: 150mg/kg over 15 minutes in 200ml of 5 per cent glucose

• Second dose: 50mg/kg over four hours in 500ml of 5 per cent glucose

• Third dose: 100mg/kg over 16 hours in 1L of 5 per cent glucose

• The last dose may be repeated according to clinical needs

Considerable thought from the prescriber is needed when writing the prescription and then from the nurse who prepares and administers the infusion. The prescriber needs to specify the actual acetylcysteine dose (in grams), fluid regimen and associated infusion times. The nurse needs to convert the dose (in grams) into a volume (ml) of injection — available as 2g in 10ml — to be added to an appropriately sized intravenous infusion container, calculate the infusion rate (in ml/h) and programme the infusion device.

The basis for such a complicated regimen, initially reported in 1977, is not known but the clinical evidence demonstrating its benefit is well established. With such a complex regimen, however, there are many opportunities for error when writing, preparing and administering a prescription for acetylcysteine.

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