Paediatric medicine - Prescribing for children

Considered prescribing is essential in child medicine.

Prescribing for children brings with it a host of potential risks. Many of these risks may go unnoticed, but occasionally they cause serious problems.

Good communication: write the exact strength required or specify the manufacturer on the prescription (Photograph: Jim Varney)

By raising awareness of some of these risks, potential errors in the treatment of one of the most vulnerable population groups can be avoided. Good prescribing for children must concentrate on ensuring that we get the basics right. Much of this is highlighted in the NSF for Children, Young People and Maternity Services (see box, below).1

Prescribing for children
  • Use good sources of information to prescribe - the BNF for Children should be used as the standard reference source.
  • Write the child's weight on the prescription if it has been used to calculate the dose.
  • Involve the child and family in decision making - this will help with compliance if the right formulation is chosen, the same brand is used (if continuation) and should avoid error if the same strength is prescribed.
  • Avoid decimal points if possible as they have been shown to lead to errors. Remember that when prescribing in whole numbers the corresponding volume to be administered may not be a whole number. For example, a 6.5kg baby requires ranitidine at 2mg/kg (13mg). It would be easy to prescribe 13mg twice a day, but the liquid is 15mg/ml and it is far better to prescribe 15mg (1ml) twice daily than ask the carer to try to administer 0.867ml.

Source: NSF for Children, Young People and Maternity Services

Responsibility of the prescriber
Many children must use medicines that are either unlicensed or are being used outside their licence (off-label).2

Although this may not be ideal, it is an essential part of healthcare practice to ensure that children are treated appropriately - denying use of such medicines may be regarded as being as negligent as not treating children at all.

New consensus guidance Making medicines safer for children - guidance for the use of unlicensed medicines in paediatric patients aims to make this common but necessary prescribing practice safer for the child as well as the prescribing GP.3

The shift of healthcare provision will inevitably mean that the prescribing and dispensing of these medicines will increasingly be required in the community.

While we could debate ad infinitum the accountability of all healthcare professionals if a prescription is not appropriate for the clinical condition, there is no question that a large proportion of responsibility will remain with the prescriber.

However, as a prescriber are you really aware of what the child is actually taking?

Not only does it need to be a quality product, fit for purpose, it also needs to be suitable for the clinical situation and age group for which it is intended.

For example, take the various strengths of liquid that can be supplied, when we know that parents or carers often carry on administering the same volume unaware of the strength.

It is important to consider that in the EU, half of all medicines used in children have never been studied in children.4

Not only does this leave doctors in the position of having to justify the evidence base of treatment, but means there is often no suitable licensed product available to administer the correct dose safely to different age groups (see boxes for examples).

Example 1. Dispersible tablets
Dispersible tablets are only licensed to give the full tablet dose. They are dispersible to aid administration. Putting a tablet in 5ml of water and giving an aliquot of 2ml to achieve 40% of the full dose to a child may not be appropriate. Dispersible does not mean dissolvable and studies of some products have shown aliquots such as these can be less than 50% accurate if not adequately dispersed prior to removing the dose.

 

Example 2. Phenobarbital Elixir BP

Even products that seem to be made for purpose need some caution. Phenobarbital Elixir BP is a liquid formulation made to high standards as a medicine used predominantly in young children. However, as it contains 38% alcohol, a 5ml dose given to a newborn baby is the equivalent of an adult having a couple of glasses of wine - alcohol which babies with their immature livers cannot handle as well as adults.

 

Example 3. Crushing a tablet

In order to crush a tablet and mix it with food or water there must be some pharmaceutical understanding of the product:

  • Does the tablet have some sort of coating that modifies release and therefore crushing may not be suitable?
  • Is the tablet formed of pellets that protect the drug from stomach acid and therefore crushing will destroy these and render the drug ineffective?
  • Does the tablet crush and quickly fall out of solution once dispersed?

Unlicensed options
If there is not a suitable licensed product to prescribe then the following unlicensed options may be considered.5 The BNF for Children gives many useful solutions to these issues.6

Extemporaneous product: this is where a pharmacist makes a product themselves. While this is very occasionally necessary, it should be avoided if possible because it usually involves little formulation data and very little built-in quality assurance.

Use of 'specials': specials are bespoke unlicensed medicines made under a Manufacturer's Specials Licence. Specials give far more guarantee that a product has been made to a high, quality-assured specification than extemporaneous products.

Different manufacturers will use different formulations and manufacturing processes for the same product, thus excipients and bioavailability will vary.

This variance may be critical to patient response with some medicines and - where possible - a patient should be kept on the same manufacturer's medication for continuity of care.

Importing products: this is often the most costly option but it can have pros and cons. If a product can be obtained by one of the big importation companies that is licensed in a country with similar regulatory standards to the UK (such as the US, Europe, Australia and Canada) then you have some guarantee of the quality of the product.

If it is licensed for the intended use then that is ideal. If it is licensed for another indication, then the same considerations as stated previously must apply.

Of course, if the product and patient information is in a foreign language it may lead to error and confusion.

While the purchase of the exact medicine may be outside the remit of the prescriber, there is much they can do to help.

If a patient is already taking a medicine or has been suggested to start a medicine via secondary care, then this should be written on the prescription to aid the pharmacist in purchasing the same medicine again.

This may mean writing the exact strength required, specifying the same manufacturer or indicating avoidance of certain excipients (such as alcohol).

All children have the right to expect that the medicine they are being given is appropriate, safe and effective for them to the best of the professional's ability.

Detailed and considered prescribing, backed up with good communication, is essential in achieving this.

  • Mr Tomlin is consultant pharmacist, Children's Services, Evelina Children's Hospital, London

References

1. DoH. National Service Framework for Children, Young People and Maternity Services. London: DoH; 2004. www.dh.gov.uk

2. Nunn A J. Making medicines that children can take. Arch Dis Child 2003; 88: 369-71.

3. Tomlin S, Cockerill H, Costello I et al. Making medicines safer for children - guidance for the use of unlicensed medicines in paediatric patients. Berkhamsted: MGP Ltd; 2009. www.eguidelines.co.uk/paediatric

4. Conroy S, Choonara I, Impicciatore P, et al. Survey of unlicensed and off label drugs used in paediatric wards in European countries. BMJ 2000; 320:79-82.

5. Tomlin S. Understanding how to select appropriate liquid medicines for children will ensure they receive the best-available product for their needs. Pharmacy in Practice 2007; 211-4.

6. BMA, the Royal Pharmaceutical Society of Great Britain, the Royal College of Paediatrics and Child Health, and the Neonatal and Paediatric Pharmacists Group. BNF for children. http://bnfc.org/bnfc/index.htm

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