Michaelis-Menten pharmacokinetics of diphenylhydantoin and application in the pediatric age patient.

Michaelis-Menten pharmacokinetics were evaluated for diphenylhydantoin given to 104 patients 0.5 to 16 years of age with seizures. A method for individualizing the dosage regimen of DPH for each patient was evaluated retrospectively. The Vmax was inversely related to age (r = 0.552, P less than 0.001) but there was no such relationship for Km. The individual pharmacokinetics were characteristic of that person and could be used to adjust dosage so that toxicity would be avoided. We present a nomogram for adjusting the dosage of DPH in the pediatric age groups.