The discovery of an antiparkinsonian drug, zonisamide; Murata M; Clinical Neurology (Rinsho Shinkeigaku) 50 (2), 67-73 (Feb 2010

http://www.ncbi.nlm.nih.gov/pubmed/20196486

We serendipitously found that zonisamide (ZNS), an antiepileptic agent, has beneficial effects on Parkinson disease. A 25 mg once a day of ZNS (200-600 mg/day for epilepsy), significantly improves motor function of advanced patients with Parkinson disease. Its effects maintained at least one year even in patients with advanced stage. It was finally approved as an anti parkinsonian agent in Japan on January 2009. As the mechanism of antiparkinsonian effects of ZNS, we showed that ZNS increases dopamine contents in the striatum by activating dopamine synthesis through increasing the levels of tyrosine hydroxylase (TH) mRNA and TH protein. It moderately inhibits monoamine oxydase (MAO) activity. ZNS shows significant inhibition on T-type Ca++ channel. It may also affect the beneficial effects of ZNS on Parkinson disease. ZNS also showed neuroprotective effects on several parkinsonian models. It markedly inhibited quinoprotein formation and increased the level of glutathione by enhancing the astroglial cystine transport system and/or astroglial proliferation through S100beta. We will verify the neuroprotective effects of ZNS on patients with Parkinson disease and study the factors responsible for the individual difference of the effects of ZNS by using genome wide association study (GWAS) in the near feature.


(as usual the drug is not without adverse effects, though it has been in use for >8yrs (and possibly longer--there exists generic forms of the drug), thus has a record over a longer period of time and in larger numbers than a new drug.
http://www.rxlist.com/zonegran-drug.htm

Its primary use is as an antiepilepsy drug; its off label uses appear to be for migrane sufferers and as an agent for neuropathic pain syndromes.
In surface researching this drug, I recall something about antichoninergic effects, though am unable to substantiate (ie cannot find the reference again). Also discovered one of the generic preparations contains lactose as a filler.
The "neuroprotective effects" is a red flag for me; becoming cynical, I guess. madelyn