Development and Validation of Rapid Stability-Indicating RP-HPLC Method for Assay and Related Substances of Solifenacin Succinate

A simple, inexpensive, rapid and novel stability-indicating reversed-phase high-performance liquid chromatographic method employing Zorbax-CN column has been developed and validated for the determination of both, assay and related substances of Solifenacin Succinate (SOL) drug substance and in its drug product. Forced degradation study of SOL was performed at acid, base, oxidative, photolytic and thermal stress conditions. Significant degradation was observed only in acidic and basic conditions. Four process and degradation impurities and have been identified by LC–MS and characterized by 1H NMR and FT-IR spectroscopy. The baseline separation of the impurities was achieved by gradient elution using phosphate buffer (pH 3.5) and a mixture of solvents (acetonitrile, methanol, and water), as mobile phase at a flow rate of 1.0 mL min−1. All impurities were quantified using a photodiode array detector (PDA) at 220 nm. The developed RP-HPLC method was validated in agreement with ICH requirements. The forced degradation studies proved the stability-indicating power of the method and hence, the validated method is useful for the intended use in routine analysis of SOL as bulk drug and in respective dosage forms. The salient feature of the presented method could be applied for assay and related substances determination of SOL in pharmaceutical laboratories and industries.