Zonisamide
Zonisamide is a sulfonamide anticonvulsant used as an adjunctive therapy in adults with partial-onset seizures.  Zonisamide may act by blocking repetitive firing of voltage-gated sodium channels, leading to a reduction of T-type calcium channel currents or by binding allosterically to GABA receptors. This latter action may inhibit the uptake of the inhibitory neurotransmitter GABA while enhancing the uptake of the excitatory neurotransmitter glutamate. Zonisamide represents an alternative for patients that remain refractory to established antiepileptic drugs. In 1989, it was approved for commercial use in Japan. The US and Europe approved it in 2000 and 2005, respectively.