Alkaline Degradation Kinetic Study of Thiocolchicoside by Stability Indicating High-Performance Thin-Layer Chromatographic Method

Abstract

A stability indicating high-performance thin-layer chromatographic (HPTLC) method was developed using aluminum plates pre-coated with silica gel 60 F254 as the stationary phase and toluene: acetone: water (1.5:7.5:1.0, v/v/v) as the mobile phase with detection wavelength 277 nm. Thiocolchicoside was subjected to degradation in alkaline, acidic, oxidative, neutral, dry heat, and photolytic conditions. Linearity was observed in the concentration range 100–500 ng/spot with correlation coefficient (R2) 0.9961. The developed method was validated for specificity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ) as per International Conference on Harmonisation (ICH) guidelines. The proposed method was successfully applied for the estimation of thiocolchicoside in pharmaceutical dosage forms and assay results were found to be in good agreement with the labeled claim of pharmaceutical dosage forms of thiocolchicoside. The proposed method was also applied for the degradation kinetic study of thiocolchicoside in 0.1 N, 0.5 N, and 1.0 N sodium hydroxide at different temperatures. The degradation of thiocolchicoside in all conditions was found to be first order and the highest degradation was found in 1.0 N NaOH at 60°C. The prediction of the degradation rate constant was also carried out at different temperatures and strengths of NaOH using Design Expert software-9 (trial version). The degradation products of thiocolchicoside formed in alkaline medium were isolated and characterized using infrared (IR), mass, and nuclear magnetic resonance (NMR) spectroscopy.