Product Code: Z010000

English Name: Zonisamide

English Alias: benzo[d]isoxazol-3-ylmethanesulfonamide

CAS Number: 68291-97-4

Molecular Formula: C8H8N2O3S

Molecular Weight: 212.23

High Purity: As a reference standard for the original drug, purity ≥99.5% (HPLC normalization), meeting the requirements of international pharmacopoeias such as USP and EP.

Stable Chemical Properties: Maintains good stability at room temperature in a dry environment, with a shelf life of up to 36 months under light-protected conditions, suitable for long-term quality monitoring.

Multi-Application Compatibility: Can be used simultaneously as a reference for assay and system suitability testing for related substances, reducing experimental costs.

Quality Control of API and Formulations: Used for assay by HPLC, UV spectrophotometry, etc., ensuring the active ingredient meets the labeled amount (98.5%-101.5%).

Impurity Qualification/Quantification: Serves as a system suitability standard to evaluate the separation capability of chromatographic methods for zonisamide-related impurities (e.g., Impurity 5, 7, 8).

Bioavailability Studies: Acts as an isotopic labeling precursor in pharmacokinetic experiments to support mass spectrometry detection of drug concentrations in biological samples.

Generic Drug Consistency Evaluation: Provides a reference for generic drug development to ensure in vitro dissolution profiles and in vivo bioequivalence meet requirements.

Detection Technology：
The mainstream method is HPLC-UV using a C18 column (4.6×250mm, 5μm) with acetonitrile-phosphate buffer (30:70, v/v) as the mobile phase, detection at 225nm, and a limit of quantification (LOQ) of 0.05%. Developed UPLC-MS/MS technology shortens analysis time to <5 minutes and enables trace impurity detection (e.g., nitrosamines, LOQ as low as 0.01ppm).

Process Optimization：
In traditional processes, the sulfonyl chloride intermediate is prone to hydrolysis to form Impurity 5 (2-(benzo[d]isoxazol-3-yl)acetic acid). Using triethylamine as a base and controlling the reaction temperature ≤5°C reduces this impurity from 0.8% to 0.03%. New catalytic synthesis routes (e.g., palladium-catalyzed coupling) reduce side reactions and increase API purity to >99.8%.

Safety Studies：
Long-term toxicity tests show the no-observed-adverse-effect level (NOAEL) of zonisamide in rats is 200mg/kg/day. Nitroso compounds in the impurity profile must comply with ICH M7(R1) for genotoxic impurities, driving the development of highly sensitive detection methods.