Implementation of two sustainable chromatographic methods for the simultaneous micro-quantitation and impurity profiling of metformin and rosuvastatin in recently approved fixed dose pills: Greenness and whiteness studies

Abstract

Rosuvastatin-Metformin is an emerging fixed dose combination (FDC) for the treatment of diabetes mellitus-associated dyslipidemia. Generally, the beneficial outcomes of FDC in reduction of pills burden, cost and complexity of medications protocols, encouraged analysts and we in turn for the development of rapid sustainable analytical methods for the simultaneous estimation of such important drug combinations. Within this framework, two validated analytical methodologies have been implemented for the neat separation and quantitation of metformin (MET) and rosuvastatin (RSV) in presence of the pharmacopeial impurities cyanoguanidine (CYG) (impurity A of MET) and the rosuvastatin-related substance B (RSV-impurity B). The latter was freshly prepared and then confirmed using Liquid Chromatography-Mass spectrometry (LC-MS). Method I represented the first electro-driven separation method for the assay of this FDC using Micellar Electrokinetic Chromatography (MEKC). The optimized conditions were 50 mM borate buffer containing 100 mM sodium dodecyl sulfate (SDS) at pH 9.2 using a deactivated fused silica capillary (50 cm effective length × 50 μm id). Method II was High Performance Liquid Chromatography (HPLC) method using Microsorb MV-C18 (4.6 × 250 mm, 5 μm particle size) column with 20 mM sodium dihydrogen phosphate buffer (pH 3.5), acetonitrile and methanol as mobile phase constituents. The separation was achieved with a linear gradient program and flow rate 1.5 mL/min all over the run. The Diode Array Detector (DAD) detector was set at wavelengths 243 nm for RSV and 235 nm for MET in both methods. The 4 peaks were separated in about 8 and 5 min for methods I and II, respectively. Linear relationships were obtained between peak areas and concentrations of metformin and rosuvastatin in the ranges 10–100 μg/mL for MEKC and 1–150 μg/mL for HPLC. The 2 techniques fulfilled the International Council for Harmonization (ICH) validation criteria, as well as the green and white analytical chemistry principles which were evaluated using the trendiest AGREE, hexagon and RGB12 tools. The interpretation of scores indicated that the suggested methods outperformed the reported methods in terms of eco-friendliness and sustainability. They offered fast, feasible, stability indicating and accurate analysis of both drugs in bulk and in pills.