The British National Formulary and many reference textbooks recommend
that drug dosages for children be calculated according to body surface
area (BSA). Although many rules for drug dosage have been developed,
based on age, weight and surface area, none has been accurate and simp
le enough for routine use. These rules are described, and one for clin
ical use: up to 30 kg, a child's drug dose may be (wt x 2)% of an adul
t dose; over 30 kg, (wt + 30)% of an adult dose. if this percentage of
an ''adult'' dose of a drug is used, not only is the BSA curve follow
ed more closely than with the conventional mg kg(-1) regimen, but fewe
r major errors of prescription may be expected.