Aspects of antiepileptic treatment in children.

About 75% of patients with epilepsy have seizures during childhood, often requiring antiepileptic therapy. Children possess all the drug-specific pharmacokinetic features of adults (e.g., nonlinearity of phenytoin elimination and autoinduction of carbamazepine metabolism), plus other factors (e.g., age, intercurrent illness, comedication) that influence dosage. Kinetic differences are maximal in newborns and infants, with limited drug elimination in premature and full-term babies, soon followed by accelerated elimination during infancy and childhood, before lower adult elimination rates develop during late childhood or early adolescence. Most children with epilepsy require two- to fourfold larger doses relative to bodyweight than adults, to achieve comparable drug levels and therapeutic effects. Although rapid growth may require increased dosage, the need is limited as relative clearance declines with age. Children of any age, but particularly premature and newborn babies, show greater individual variability in drug handling and therefore in dose requirements than adults. Clinical response and antiepileptic drug concentrations should both be monitored carefully in children.