Methsuximide for refractory complex partial seizures.

The efficacy and safety of methsuximide were evaluated for 12 weeks in 21 patients with complex partial (psychomotor) seizures refractory to conventional anticonvulsants. After addition of methsuximide to the previous anticonvulsant regimens, the number of complex partial seizures per patient decreased from a weekly average of 5.8 to 0.9 seizures. A 90 to 100% control of complex partial seizures was achieved in 15 (71%) of the patients. Dose reduction or discontinuation of one or more previous medications was possible in 42%. Seizure control was optimal at methsuximide doses of 9.5 to 11.0 mg per kilogram per day and plasma levels of 20 to 24 micrograms per milliliter. Adverse experiences, particularly somnolence and lethargy, were reported by 12 patients. Methsuximide appeared to be an effective and generally well tolerated adjunct medication in the management of complex partial seizures.