Phenytoin elimination kinetics in two children with drug intoxication.

Two girls aged 6 and 10 years treated with anticonvulsants developed nystagmus and ataxia. The peak plasma concentrations of phenytoin were 42.6 and 46.6 microgram/ml, respectively, compatible with phenytoin toxicity. The decline in plasma phenytoin levels did not fit first order kinetics, but followed Michaelis-Menten kinetics.