What I learn this week: Paracetamol – a simple drug with not so simple dosing? #WILTW

This is the 37th WILTW

A while ago I was surprised to find an unusual dose of paracetamol written on an anaesthetic° friend’s kitchen wipeboard (1.2ml). On closer questioning it transpired that his son had developed a viral illness while on holiday in Spain.  The anaesthetist was frustrated as he could only buy a small volume of paracetamol and spent a long time negotiating for a 90ml bottle. On returning to his holiday residence he realised the reason for the pharmacist’s reluctance – in Spain a 100mg/ml concentration is used.  Although this is a standard European dose, in the UK it is more common to have 250mg/5ml which is half the amount per mililitre.

Figure One

The wipeboard contained relevant values for the son’s age but had such diligence not be applied to reviewing the actual dosage it is possible that an un-intentional overdose may have been given. I had thought of submitting this as a case report to alert Paediatricians, GPs, Pharmacists and Parents to the potential problems that buying medications in countries outside of their country of origin may bring (and also a weight rather than volume based syringe may be helpful as parents sometimes find dosing difficult [1]).

Figure 2This case sprang to mind as I have recently reviewed some literature on liver injury secondary to paracetamol overdose [2]. The study based on data from Australia and New Zealand revealed the majority were in small children (< 5) as a result of parental medication errors. An (unrelated) discussion on twitter this week therefore caught me eye. It related to the use of 30mg/kg of paracetamol as a loading dose to aid discharge of chidren from Emergency Departments

I’m going to try to steer clear of the ‘fever’ treatment debate in this blog but I think this is a salient reminder of the dangers of variable medication volumes in children. While I can see the pharcomological rational behind the loading dose, the potential for confusion does exist, especially if parents mis-interpret its use. While I have previously highlighted the medical profession are a little paternalistic about parental decision making (thoughts here) there is evidence children have come to harm as a result medical errors. The work mentioned in the tweet only suggested an improved reduction in temperature, rather than other clinical outcomes, so for me currently there is no a clear reason to use the larger dose. If this was proven to reduce distress in children to the extent disposition decisions could be more safely and effeciently made then I suspect the whole fever debate will be re-ignited!

Until then we know medication errors occur as a result of health care professional and parental/carer mistakes. We should continue to do all we can to ensure we work towards them being never events.

What did you learn this week? #WILTW

°Many thanks to Richard Eve for being so thorough with his dosing calculations!

  1. Marlow R, Lo D, Walton L. Accurate paediatric weight estimation by age: mission impossible? Arch Dis Child 2011;96:A1-A2
  2. Rajanayagam JBishop JRLewindon PJEvans HM. Paracetamol-associated acute liver failure in Australian and New Zealand children: high rate of medication errors. Arch Dis Child. 2015 Jan;100(1):77-80

One thought on “What I learn this week: Paracetamol – a simple drug with not so simple dosing? #WILTW”

  1. The fact that the BNF clearly states 20mg/kg as a loading dose would make giving anything bigger a very difficult action to support if anything went wrong (in the UK).
    I agree the different preparations of paracetamol do mean you need to ensure you know which one has been given- even the concentrations of good old Calpol change in the under and over 6 varieties (and not in an intuitive way). My personal practice is to always ask the brand name and if an unusual one try and see the bottle.

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