Abstracts

Zonisamide (ZNS) was introduced in Japan since 1991, and has been acknowledged as a safe and efficient anticonvulsant. There was a suggestion that ZNS was safe and better tolerated to elderly patients in post-market multi-center safety study in Japan. It[apos]s longer elimination half-life allows reliable once-a-day drug regimen. Side effects of ZNS includes GI upset, dizziness, skin rash, and acute psychosis in Japanese articles, but the incidence of them are believed less in older patients for unknown reasons. There has been so far no report for utilization of ZNS exclusively in elderly epileptic population.
This is a retrospective outcome review in the outpatient neurology clinic in Saginaw VA Medical Center. Zonisamide was utilized in those patients whose seizure was not under control (more than one episode per month) with other AEDs previously. 20 consecutive patients of complex partial seizure, whose seizure control was resistant to at least three preexisting AED, age range 49 to 89 (average 64.1), were identified. ZNS was added on the concurrent AEDs in all cases expecting adjunctive benefit. The starting dose was 100mg po qd. The patiens were followed for two months and the dose was increased to 100mg bid or 200mg qd if patients could tolerate ZNS, but clinical improvement was not sufficient. The dose was not increased if patients could attain significant seizure frequency reduction greater than 50%. Follow-up period varies from 4 to 12 months.
Among the above identified 20 patients, 4 patients had post-anoxic etiology, 3 had post-trauma, 3 had post-stroke etiology, and 10 had unknown cause. In the review, three patients became seizure-free. 16 patients out of 20 (80%) experienced greater than 50% reduction in seizure frequency with the low adjunctive ZNS with no greater than 200 mg/day. Clinical improvement did not correlate with etiology. Three patients discontinued ZNS. One experienced skin rash, and one experienced visual hallucination, and the other had excessive drowsiness. None experienced paradoxical aggravation of seizure frequency. Among the sixteen patients whose seizure improved, 5 patients experienced mild drowsiness and GI upset, but they continued ZNS. No patients experienced kidney stones or acute psychosis. Once a day regimen was allowed, and no single patient had compliance problem.
ZNS adjunctive therapy was well tolerated and successful to elderly patients of intractable complex partial seizure disorder in neurology outpatient clinic. Seizure responder rate, defined as [gt]50% seizure frequency reduction, was unexpectedly well in elderly epileptic patients with minimal side effects. Once a day regimen is easy for elderly patients and contributing better compliance. The fndings of this preliminary retrospective study suggests that ZNS adjunction is effective in low dose with less adverse effects in elderly epilepsy.