Kinetics of intravenous phenytoin in children.

Single-dose intravenous phenytoin (9.4-21.3 mg/kg) effectively eradicated seizures within 3 minutes in 12 out of 13 patients in status epilepticus. Eleven additional patients were treated prophylactically. No adverse effects were observed and neurological status was unaltered in all 24 cases. Phenytoin volume of distribution was found to decline significantly with age from 1.6 L/kg at 1 year to 0.6 at 10 years (P less than 0.01). Estimates of Vmax, the maximal rate of phenytoin metabolism, were obtainable in 8/24 patients and were in the expected range (10.6 +/- 4.2 mg/kg/day) for their age (6.6 +/- 2.8 years). Therapeutic serum concentrations (initial post distribution values 17.9 +/- 9.0 micrograms/ml) were maintained for more than 10 hours in 15/24 patients. Single-dose intravenous phenytoin is both effective and safe in the treatment and prevention of epileptic seizures in pediatric patients.