Zonisamide: a new drug for Parkinson's disease

Zonisamide is a benzisoxazole derivative and an anti-epileptic drug with a long half life. In 2009 in Japan, three nationwide, double-blind, placebo-controlled studies were carried to evaluate zonisamide as a therapeutic option for the treatment of advanced Parkinson’s disease. The addition of 25-30 mg/day of zonisamide to currently used anti-Parkinsonian drugs significantly improved cardinal symptoms, and the effects were maintained following continuous administration for more than 1 year. The mechanisms underlying the anti-Parkinsonian action of zonisamide are unclear, but may include activation of dopamine synthesis, inhibition of monoamine oxidase, inhibition of T-type calcium channels, inhibition of the indirect pathway in the basal ganglia via the sigma opioid receptor, and the activation of the astroglial cysteine transport system or astroglial proliferation through S100beta production and secretion.