Low Level Determination of 4-Amino-2-Ethoxy-Cinnamic Acid and its Ethyl Ester in a Drug Substance and its Formulation Prototypes by HPLC-UV-DAD

摘要

A reversed-phase high-performance liquid chromatographic method (HPLC) with diode-array detection (DAD) has been evaluated for monitoring trace levels of impurities, such as 4-amino-2-ethoxy-cinnamic acid (impurity A), hydrochloride salt of 4-amino-2-ethoxy-ethyl cinnamate (impurity B), and 4-bromo-3_ethoxy-nitrobenzene (impurity C), in drug substance and 3 different formulation prototypes. These compounds have been highlighted as potential genotoxins and 2-ethoxy-4-amino-cinnamic acid (impurity A) as possible degradant isolated during the synthesis of B1 drug substance. HPLC_UV-DAD was found to be more promising, and limits of quantification were between 0.09 and 0.6 μg/mL, which enabled detection limits in drug substance at 2-15 ppm for a 15 mg/mL solution. All three genotoxic impurities are completely resolved from each other as well as from diluent peaks, drug substance, and other related impurities within 40 min. The retention times of impurities A, B, and C were 3.4, 13.1, and 21.3 min. The results demonstrating the specificity, assay precision, recovery, linearity, and range achieved during the method validation experiments are presented in this paper.