• Pharmacology
• Therapeutics
• Obesity
• Paediatric Practice
• Anaesthetics

A survey conducted by Collier et al 1 highlights the problem of drug dosing in obese children. The authors identify two aspects that require greater attention from paediatric practitioners: the identification of the obese child and the lack of use of ideal body weight (IBW) for drug calculation in that obese child. Both involve effort from prescribers to go beyond simply measuring total body weight (TBW). There remains a question about the benefits of using IBW compared with using TBW or any other measure of body mass. The lack of enthusiasm to calculate IBW obvious from the Collier et al survey is reflective of uncertainty concerning dose calculation in the obese child.

Collier et al propose anecdotally that using IBW rather than TBW would have avoided toxicity from an overdose of aminophylline. While we agree that aminophylline maintenance doses using TBW may be over-predicted in obesity, initial dosing based on either IBW or TBW for a target concentration (TC) of 10 mg/L is unlikely to be toxic.2 While the use of TBW to calculate initial doses may not be ideal for the maintenance dose, the problem could have been avoided by measuring …