Single drug therapy for intractable epilepsy.

Single drug therapy with either phenytoin or primidone resulted in complete seizure control in 11 of 35 patients (31%) referred to an epilepsy clinic for treatment of uncontrolled chronic epilepsy with complex-partial seizures. Complete seizure control was associated with an increase in the mean plasma concentrations from 14 micrograms/ml to 23 micrograms/ml phenytoin and from 34 micrograms/ml to 40 micrograms/ml phenobarbitone with no change in the antiepileptic drug. Insufficiently low plasma concentrations of less than 11 micrograms/ml phenytoin or phenobarbitone were measured at the first visit in 14 patients (40%). Non-compliance was admitted by eight patients (23%). Optimum single drug therapy is of considerable clinical value in intractable epilepsy with complex-partial seizures.