Identification and in vitro genotoxicity assessment of forced degradation products of glimepiride and glyburide using HEK cell-based COMET assay

This study focuses on characterizing the forced degradation products of antidiabetic drugs glimepiride (GMD) and glyburide (GBD), with previously unexplored genotoxicity. Drugs underwent stress induced by acid, base, and hydrogen peroxide. For GMD, impurities were profiled and isolated using Hypersil Gold C8 (250 × 10 mm, 5 μ) through semi-preparative HPLC with a fraction collector. For GBD, impurity profiling was performed using semi-preparative HPLC (Hypersil GOLD C18, 250 × 10 mm, 5 μ), and reverse-phase flash chromatography (FP ECOFLEX C18 4 g column) for isolation. Although five GMD and three GBD impurities were detected, only three GMD and two GBD impurities were separated and assessed for purity using analytical RP-HPLC with the purity percentages ranging from 96.6% to 99.9%. LC-Orbitrap MS was used to identify these three GMD impurities (m/z: 408.122, 338.340, 381.160) and two GBD impurities (m/z: 369.065, 325.283). ProTox-II in silico predictions classified all impurities as class 4 and 5, with no positive genotoxicity indications. In vitro comet assays, using HEK cells, indicated that for GMD, impurity 2 and impurity 5 were less genotoxic, whereas impurity 4 exhibited genotoxicity. For GBD, both impurities 1 and 3 were found to be genotoxic, with impurity 3 showing a higher level of genotoxicity than impurity 1.