We determined the efficacy of and tolerability to
zonisamide (ZNS) in newly diagnosed patients with
infantile spasms. ZNS, 4-20 mg/kg per day, was introduced as an add-on
therapy or monotherapy in 27 children with
infantile spasms (cryptogenic, 2; symptomatic, 25). The dosage was initially 2-4 mg/kg per day, and then was increased by 2-5 mg/kg every 2-4 days until the
seizures disappeared. Nine (33.3%) out of the 27 patients who were administered ZNS exhibited the disappearance of
seizures. ZNS was effective in all the cryptogenic cases and seven (28.0%) of the symptomatic cases. The effective daily doses were 5-12.5 mg/kg (mean, 7.8 mg/kg), and the daily dosages were 40-100 mg (mean, 61.1 mg). The steady-state plasma ZNS concentrations were almost within the therapeutic range. The mean time interval between the start of ZNS
therapy and the seizure disappearance was 5.0 days. Six (75.0%) of eight effective cases, the exception being one for whom EEG was not performed after the
therapy, showed the disappearance of
hypsarrhythmia. The recurrence of
seizures were observed in four of the nine cases. No adverse reaction to ZNS was noted in any patient. In conclusion, ZNS treatment is considered to be worthwhile trying, for early stage
therapy for
infantile spasms.