Zonisamide-¹³C₂,¹⁵N

Zonisamide-¹³C₂,¹⁵N is intended for use as an internal standard for the quantification of zonisamide (Item No. 24183) by GC- or LC-MS. Zonisamide is an antiepileptic agent.¹ It selectively inhibits the repeated firing of sodium channels (IC₅₀ = 2 μg/ml) in mouse embryo spinal cord neurons and inhibits spontaneous channel firing when used at concentrations greater than 10 μg/ml.² In rat cerebral cortex neurons, zonisamide (1-1,000 μM) inhibits T-type calcium channels with a maximum reduction of 60% of the calcium current.³ Zonisamide inhibits H. pylori recombinant carbonic anhydrase (CA) and the human CA isoforms I, II, and V with K_i values of 218, 56, 35, and 21 nM, respectively.^4,5 In mice, it has anticonvulsant activity against maximal electroshock seizure (MES) and pentylenetetrazole-induced maximal, but not minimal, seizures (ED₅₀s = 19.6, 9.3, and >500 mg/kg, respectively). Zonisamide (40 mg/kg, p.o.) prevents MPTP-induced decreases in the levels of dopamine (Item No. 21992), but not homovanillic acid (HVA; Item No. 27307) or dihydroxyphenyl acetic acid (DOPAC; Item No. 24912), and increases MPTP-induced decreases in the dopamine turnover rate in mouse striatum in a model of Parkinson's disease.⁶ Formulations containing zonisamide have been used in the treatment of partial seizures in adults with epilepsy.

WARNING This product is not for human or veterinary use.

1. Masuda, Y., Ishizaki, M., and Shimizu, M. Zonisamide: Pharmacology and clinical efficacy in epilepsy. CNS Drug Rev. 4(4), 341-360 (1998).

2. Rock, D.M., Macdonald, R.L., and Taylor, C.P. Blockade of sustained repetitive action potentials in cultured spinal cord neurons by zonisamide (AD 810, CI 912), a novel anticonvulsant. Epilepsy Res. 3(2), 138-143 (1989).

3. Suzuki, S., Kawakami, K., Nishimura, S., et al. Zonisamide blocks T-type calcium channel in cultured neurons of rat cerebral cortex. Epilepsy Res. 12(1), 21-27 (1992).

4. Nishimori, I., Vullo, D., Minakuchi, T., et al. Carbonic anhydrase inhibitors: Cloning and sulfonamide inhibition studies of a carboxyterminal truncated α-carbonic anhydrase from Helicobacter pylori. Bioorg. Med. Chem. Lett. 16(8), 2182-2188 (2006).

5. De Simone, G., Di Fiore, A., Menchise, V., et al. Carbonic anhydrase inhibitors. Zonisamide is an effective inhibitor of the cytosolic isozyme II and mitochondrial isozyme V: Solution and X-ray crystallographic studies. Bioorg. Med. Chem. Lett. 15(9), 2315-2320 (2005).

6. Yabe, H., Choudhury, M.E., Kubo, M., et al. Zonisamide increases dopamine turnover in the striatum of mice and common marmosets treated with MPTP. J. Pharmacol. Sci. 110(1), 64-68 (2009).