Title: Zonisamide
CAS Registry Number: 68291-97-4
CAS Name: 1,2-Benzisoxazole-3-methanesulfonamide
Additional Names: 3-(sulfamoylmethyl)-1,2-benzisoxazole
Manufacturers' Codes: AD-810; CI-912
Trademarks: Excegran (Dainippon); Zonegran (Dainippon)
Molecular Formula: C8H8N2O3S
Molecular Weight: 212.23
Percent Composition: C 45.27%, H 3.80%, N 13.20%, O 22.62%, S 15.11%
Literature References: Sulfonamide antiseizure agent; blocks repetitive firing of voltage-sensitive sodium channels and reduces voltage-sensitive T-type calcium currents. Prepn: H. Uno et al., JP Kokai 78 77057; eidem, US 4172896 (1978, 1979 both to Dainippon); eidem, J. Med. Chem. 22, 180 (1979). Pharmacology and toxicity: Y. Masuda et al., Arzneim.-Forsch. 30, 477 (1980). Mode of action study: T. Ito et al., ibid. 603. HPLC determn in serum: U. Juergens, J. Chromatogr. 385 233 (1987). Clinical trial in epilepsy: D. Schmidt et al., Epilepsy Res. 15, 67 (1993). Review of neuropharmacology: E. J. Hammond et al., Gen. Pharmacol. 18, 303 (1987); of pharmacokinetics and therapeutic potential: D. H. Peters, E. M. Sorkin, Drugs 45, 760-787 (1993); of pharmacokinetics and mechanism of action: I. E. Leppik, Seizure 13S, S5-S9 (2004).
Properties: White needles from ethyl acetate, mp 160-163° (Uno); also reported as mp 162-166° (Masuda, 1980). pKa 10.2. Soly (mg/ml): water 0.80; 0.1 N HCl 0.50. Sparingly sol in chloroform, n-hexane. Sol in methanol, ethanol, ethyl acetate, and acetic acid. LD50 in mice, rats (mg/kg): 1892, 2001 orally; 1273, 2569 s.c.; 699, 733 i.p.; 604, 748 i.v. (Masuda, 1980).
Melting point: mp 160-163° (Uno); mp 162-166° (Masuda, 1980)
pKa: pKa 10.2
Toxicity data: LD50 in mice, rats (mg/kg): 1892, 2001 orally; 1273, 2569 s.c.; 699, 733 i.p.; 604, 748 i.v. (Masuda, 1980)
Therap-Cat: Anticonvulsant.
Keywords: Anticonvulsant.
Zopiclone Zopolrestat Zosuquidar Zotepine Zoxamide

Systematic (IUPAC) name
Clinical data
Trade names Zonegran
AHFS/Drugs.com monograph
MedlinePlus a603008
Pregnancy cat. D (AU) C (US)
Legal status Prescription Only (S4) (AU) -only (CA) POM (UK) -only (US)
Routes Oral
Pharmacokinetic data
Bioavailability ~100%[1]
Protein binding 40%[1]
Metabolism Hepatic through CYP3A4[1]
Half-life 63 hours in plasma[1]
Excretion Renal (62%); Faeces (3%)[1]
CAS number 68291-97-4 YesY
ATC code N03AX15
PubChem CID 5734
DrugBank DB00909
ChemSpider 5532 YesY
UNII 459384H98V YesY
KEGG D00538 YesY
ChEBI CHEBI:10127 YesY
Chemical data
Formula C8H8N2O3S 
Mol. mass 212.227 g/mol
Physical data
Melt. point 162 °C (324 °F)
 YesY (what is this?)  (verify)

Zonisamide is a sulfonamide anticonvulsant approved for use as an adjunctive therapy in adults with partial-onset seizures; infantile spasm, mixed seizure types of Lennox-Gastaut syndrome, myoclonic, and generalized tonic clonic seizure.[2]