[Effect of zonisamide on resting tremor resistant to antiparkinsonian medication]

The antiparkinsonian effect of zonisamide (ZNS), an antiepileptic agent, has been reported. Generally, resting tremor of patients with Parkinson's disease is not the main therapeutic target in this disease. However, depending on the social situation of the patient, the amelioration of the tremor may be necessary. In this study, we examined the effect of ZNS on tremor in nine patients who desired amelioration of their tremor. Except for tremor, they seemed to be under optimal therapeutic condition based on their daily activities. By the add-on administration of ZNS, the degree of tremor was reduced in seven out of nine patients (p < 0.0017). Although one patient felt sleepiness and two patients had a transient loss of appetite, all the patients tolerated the eight-week ZNS administration period. The final dose of ZNS was 100 mg/day in the majority of the patients. Although the mechanism of the antitremulous effect of ZNS is not yet clear, other than the enhancement of dopaminergic transmission, some specific action of the drug on tremor may exist. A more detailed random examination should be carried out.