Broad-spectrum efficacy of zonisamide at 12 months in children with intractable epilepsy

In a retrospective study of 35 children (ages 8 months to 22 years; mean age 9 years) with intractable epilepsy, seizure frequency was determined before and after 12 months of zonisamide therapy. Charts were reviewed for seizure type (focal, generalized, or mixed), cognitive function (no special education versus special education), concomitant anticonvulsant medications, and the number of previous anticonvulsant drugs. Good to excellent seizure control (50-100% reduction) was attained in seven (54%) patients with generalized seizures, two (40%) patients with focal seizures, five (35%) patients with mixed seizures, and one (33%) patient with infantile spasms. In this group of children, the efficacy of zonisamide was comparable for focal, generalized, and mixed seizures. The efficacy of zonisamide was independent of cognitive status.Adverse effects were not associated with a higher mean dose. This could be attributable to different rates of metabolism or represent idiosyncratic responses to the medication. Our finding that those children taking the combination of zonisamide and levetiracetam had a significantly worse outcome than those on levetiracetam and a different drug warrants further study, both clinically and from the standpoint of mechanisms of action of zonisamide and levetiracetam and/or their pharmacodynamic interactions.