Zonisamide improves motor function in Parkinson disease: a randomized, double-blind study.

OBJECTIVE To evaluate the efficacy, safety and tolerability of daily doses of 25, 50, and 100 mg of zonisamide (ZNS) administered as adjunctive treatment in patients with Parkinson disease (PD). METHODS We conducted a multicenter, randomized, double-blind, parallel-treatment, placebo-controlled study in Japan. Patients with PD who showed insufficient response to levodopa treatment were given placebo for 2 weeks and then treated for 12 weeks with 25, 50, or 100 mg/day of ZNS or placebo, in addition to levodopa, followed by a 2-week dose-reduction period. The primary endpoint was change from baseline in the total score of the Unified Parkinson's Disease Rating Scale (UPDRS) Part III at the final assessment point. Secondary endpoints included changes from baseline in total daily "off" time; total scores of UPDRS Parts I, II, and IV; and Modified Hoehn and Yahr Scale score. Safety analysis was based on the incidence of adverse events. RESULTS There was significant improvement in the primary endpoint in the 25-mg and 50-mg groups vs placebo. The duration of "off" time was significantly reduced in the 50-mg and 100-mg groups vs placebo. Dyskinesia was not increased in ZNS groups. The incidence of adverse effects was similar between the 25-mg, 50-mg, and placebo groups but higher in the 100-mg group. CONCLUSIONS Zonisamide is safe, effective and well tolerated at 25 to 100 mg/day as an adjunctive treatment in patients with Parkinson disease.