Surface area-based dosing of caspofungin in children

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Caspofungin is an echinocandin antifungal which can be used to treat invasive fungal infections caused by organisms such as Aspergillus spp, including cultures that exhibit resistance to triazole antifungals.

Caspofungin is one of a relatively small number of drugs for which dosing is based on the derived value of body surface area rather than directly measured parameters such as weight. Several physiological variables responsible for drug deposition can be normalised for by using body surface area for initial dosing, which can reduce the incidence of toxicity and adverse drug reactions for drugs dependent on them.

The following calculation considers the use of caspofungin to treat invasive aspergillosis in a 15-month-old child weighing 9.98 kg with a length of 77.7 cm. To calculate the body surface area, calculate the product of the weight (in kg) and the height (in cm), divide the result of this by 3600 and then calculate the square root of that value (Du Bois and Du Bois, 1989). Body surface area  (m2)=height (cm)×weight (kg)3600