Zonisamide in Parkinson's disease: a current update

Parkinson's disease (PD) is a progressive neurodegenerative disease due to the depletion of the neurotransmitter dopamine in basal ganglia. There is a scarcity of available therapies for motor and non-motor symptoms of PD. Zonisamide (ZNS) may be one such potential candidate to alleviate PD symptoms. It was serendipitously found to be useful for PD in a patient with both epilepsy and PD. Since then, there have been many clinical trials, case series, observational studies, and case reports published supporting the efficacy of ZNS in PD. This review focuses on the efficacy and usefulness of ZNS in various motor and non-motor symptoms of PD. A predefined inclusion and exclusion criteria were used for the search protocol and databases searched were PubMed, Cochrane Library, Ovid, and clinicaltrials.gov. Most of the randomized clinical trials used UPDRS III as the primary efficacy point and showed positive results favouring ZNS. This review shows that there is evidence of the efficacy of ZNS in motor symptoms as an adjunctive therapy to levodopa, but for non-motor symptoms, the evidence is lacking and needs further investigation.