Stability-Indicating Spectrofluorimetric Method for the Assay of Ziprasidone in Capsules

A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of ziprasidone hydrochloride (ZPS) in capsules. The method is based on measuring the native fluorescence of ZPS in acetate buffer of pH 4.5 at 398 nm after excitation at 315 nm. The fluorescence-concentration plot was rectilinear over the range of 0.05–0.80 μg mL⁻¹ with a lower detection limit (LOD) of 6.0 ng mL⁻¹ and quantification limit (LOQ) of 20.0 ng mL⁻¹. The method was fully validated and successfully applied to the determination of ZPS in its capsules with average percentage recovery of 99.7 ± 1.4. The method was extended to stability study of ZPS. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and oxidative degradation of the drug. A proposal for the degradation pathways was postulated.