Stability-indicating HPTLC method for the simultaneous detection and quantification of alfuzosin hydrochloride, solifenacin succinate along with four of their official impurities

Abstract

Stability and impurity profiling of new drug formulations are now receiving great attention in modern pharmaceutical analysis. In this work, a novel stability-indicating HPTLC coupled with densitometric quantification was developed for the simultaneous determination of alfuzosin (ALF) and solifenacin (SOL) along with their degradation products/official impurities. The two drugs were subjected to different stress conditions. ALF was liable to acidic and basic hydrolysis, while SOL was found to be susceptible to basic and oxidative degradation. The obtained degradation products, namely; ALF impurity-D and SOL impurities-A, E and I were then characterized by IR and mass spectrometry. Chromatographic separation was then performed on HPTLC silica plates 60 F254, as a stationary phase, using ethyl acetate: toluene: ethanol: ammonia (5: 2: 3: 0.4, by volume), as a mobile phase. The plates were scanned at 220 nm and visualized by iodine vapor in daylight. Effect of different factors, including the mobile phase composition and the detection wavelengths, were carefully studied to achieve the optimum conditions for chromatographic separation. Calibration curves were constructed over the ranges of 0.8 – 30.0 µg/band for ALF and SOL, 0.5 – 15.0 µg/band for ALF imp-D, 0.5 – 4.0 µg/band for SOL imp-I and 0.75 – 7.50 µg/band for SOL basic degradation. The method was also exploited for assessment of the two drugs’ stability in Solitral® capsules under accelerated storage conditions. The proposed method has many potentials of being simple, economic and selective making it an attractive procedure in analyzing not only the two cited drugs but also their impurities.