Determination and Validation of Zonisamide and its Four Related Substances by HPLC and UV-Spectrophotometry

A selective and sensitive liquid chromatographic method has been developed for simultaneous determination of zonisamide and its four related substances in pharmaceutical dosage forms. The assay involved an isocratic elution in perfectsil Target C18 column using a mobile phase composition of disodium hydrogen phosphate buffer, acetonitrile and methanol (650:150:200 v/v, pH adjusted to 3±0.05) with flow rate 1.2 ml/min and analyte monitored at 240 nm. Also a simple and precise spectrophotometric method was developed for dissolution studies. These proposed methods are sensitive, accurate, reproducible and useful for the routine determination of zonisamide in pharmacy.