In silico toxicity assessment and trace level quantification of potential genotoxic impurities in imipramine...

Since the adoption of the ICH M7 guidelines in 2014, pharmaceutical industries have been mandated to screen all reagents and chemicals used in drug synthesis for genotoxicity. Genotoxic impurities (GTIs) have the potential to induce mutations in DNA, which may lead to cancer. Unlike routine impurities, the threshold for controlling GTIs is extremely low. Imipramine hydrochloride (IH) is a commonly used antidepressant; however, the genotoxicity of both the drug and their impurities remain unknown. In this study, we systematically investigate the raw materials, intermediates, and known impurities involved in the synthesis pathway of IH for their potential genotoxicity. We employed in silico prediction tools to evaluate the toxicity of the impurities, intermediates, and raw materials used in the synthesis of IH, in accordance with ICH M7 guidelines. In silico prediction results revealed two specific impurities, 2,2-dinitro-1,2-diphenylethane (DNB) and 2,2-amino-1,2-diphenylethane (DAB), as potentially genotoxic. Furthermore, molecular docking and simulation studies were conducted to evaluate the specific interactions of these impurities with DNA. The results demonstrated consistent interactions of these impurities with the dG-rich region of the DNA duplex, particularly at the minor groove. Both in silico predictions and molecular docking studies corroborated the genotoxic nature of these impurities. As part of our risk assessment and control strategy, we developed and validated an HPLC-UV method in accordance with ICH guidelines to identify both GTIs in the final active pharmaceutical ingredient (API) of imipramine. This study will assist manufacturers of IH in controlling these genotoxic impurities to ensure its safe consumption.