Medication prescribing in children

Useful drug resources

    Prescribing of medications in children is different to adults.

    The following points must be adhered to at all times when prescribing medications for children:

    Most medications are prescribed on a per kilogram basis for children under 50 kg *

    • Ensure you check the dosing per kg with a paediatric dosing reference prior to prescribing
    • Once a child is over 50 kg or if the drug, when calculated per kg, reaches the adult dose, the adult dose should be prescribed. Never exceed the maximum adult dose (e.g. a 60 kg child receiving a stat dose of paracetamol should receive the adult dose of 1g, not 20 mg/kg x 60 = 1.2g).
    • You must document the basis of your dose calculation (e.g. mg/kg/dose or other units) on the drug chart for every medication (other than those that do not require weight based calculations).
    • Ensure that the child's documented weight is current, and is roughly what you would expect based on their age, before prescribing.
      • for children aged 1-7 years, rough formula is (age + 4) x 2
      • please use the relevant WHO growth charts or the EMR growth charts in BOSSnet when unsure.
    • for neonates always use birth weight for medication calculations until the current weight exceeds the birth weight.
    • all weights at BHS should be double checked by nursing staff when they are first recorded.

    * Occasionally body surface area (BSA) is used to determine paediatric doses for some narrow therapeutic index medications e.g. IV aciclovir, chemotherapy, some electrolyte corrections

      • an accurate and current weight and height is required to determine BSA
      • take extra care when determining doses based on BSA as the calculation is more difficult
      • BSA = SQR [weight (kg) x height (cm) / 3600]

    Drugs which are fat soluble must be dosed at ideal body weight (IBW), not total body weight (TBW).

    • this is very important to avoid toxicity of some commonly used drugs, and calculating medication doses in obese patients based on their TBW puts them at risk of being prescribed an overdose.
    • calculating IBW is done by measuring height and plotting this, then taking the equivalent percentile line for the child's age on the weight chart.
    • medications that require dosing based on IBW:
      • aciclovir
      • carbamazepine
      • digoxin
      • gentamicin (use adjusted body weight: ABW = 0.4 (TBW - IBW) + IBW)
      • methylprednisolone
      • midazolam (maintenance doses)
      • paracetamol
    • medications that require dosing based on TBW:
      • enoxaparin
      • heparin
      • vancomycin
    • seek the advice of the pharmacy department for dosing information in obese patients when in doubt.

    There are certain drugs that have particular safety concerns when prescribing in children

    • aspirin - not recommended in any children < 12 years unless under paediatrician supervision
      • increased risk of Reye syndrome (acute hepatic encephalopathy)
    • cefaclor (Ceclor) - not recommended in children, suitable alternative should be used
      • high risk of serum sickness reaction 7-10 days later.
    • ceftriaxone - not recommended in neonates (use cefotaxime instead)
      • can displace bilirubin and lead to increased hyperbilirubinaemia
    • codeine - not recommended in children < 12 years, or post adenotonsillectomy < 18 years
      • risk of respiratory failure
    • co-trimoxazole (Bactrim) - not recommended in neonates (use trimethoprim alone instead)
      • can displace bilirubin and lead to increased hyperbilirubinaemia
    • ibuprofen (Nurofen) - contraindicated in infants < 3 months old.
    • metoclopromide (Maxalon) - not recommended in any children < 12 years, suitable alternative should be used (e.g. ondansetron)
      • risk of oculogyric crisis - reversal agent is benztropine
    • prochlorperazine (Stemetil) - not recommended in any children < 12 years, suitable alternative should be used (e.g. ondansetron)
      • risk of oculogyric crisis - reversal agent is benztropine
    • tetracyclines (doxycycline, minocycline) - not recommended in children < 8 years
      • can cause tooth discolouration & enamel dysplasia as well as possible bone problems.
    • tramadol - not advised in children < 12 years, or post adenotonsillectomy < 18 years
      • risk of respiratory failure