Review on how to calculate medicine doses in children who are obese which includes a table on commonly prescribed medicines.

  • Obesity results in physiological changes that can affect the volume of distribution and the clearance of drugs. The extent of these changes is variable and depends upon both patient –specific factors and the physico-chemical properties of the drug.
  • There are a lack of pharmacokinetic data on the use of commonly used drugs in obese children, therefore knowledge of which size descriptor to use in determining the optimum dose for this group of patients is limited.
  • Drug-dosing guidelines are typically derived from available data in adults who are obese.
  • Height measurements are needed on admission to hospital to identify obesity and to calculate doses based on the appropriate size descriptor.
  • Evidence-based, locally agreed guidance is required indicating which method to use for IBW calculation and which size descriptor to use for commonly used drugs in children to reduce variability and ensure optimal effectiveness and safety.
  • Although this information is provided to guide prescribers on dosing, each patient is individual and they should be clinically monitored and regularly reviewed for side effects (safety) and treatment response (efficacy).
  • In an emergency setting, actual body weight (or estimated body weight) may be used to prevent delay of treatment.


Update history

  1. RCPCH endorsed and logo added
  2. Additional medicines added to table 2.
  3. Removal of lean body mass section and algorithm for drug dosing as no longer relevant to paper.
  4. Additional information on Moore's method as a preferred method for IBW.
  5. Addition of WHO chart and STAMP tool as useful reference tools.
  6. Published

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