Development and Validation of an HPLC Method for the Simultaneous Determination of Eight Related Substances in Fosaprepitant Dimeglumine API

The purpose of this study was to develop and validate a robust, precise, and selective high-performance liquid chromatography (HPLC) method for the separation and determination of related impurities in fosaprepitant dimeglumine API. The chromatographic separation was performed on a Supersil ODS-2 column (250 x 4.6 mm, 5 mu m) at a wavelength of 215 nm using a mixture of phosphate buffer (pH 2.15) and acetonitrile as the mobile phase in gradient elution mode. The validation results demonstrate that the method exhibits acceptable specificity, linearity, accuracy, precision, and robustness. The detection limits and quantitation limits ranged from 1.5 to 12.5 ng mL-1 and from 3.0 to 37.5 ng mL-1, respectively. A linear relationship was observed between the peak area and concentration of fosaprepitant and its eight related impurities with a correlation coefficient value of r2 >= 0.999. The analysis of commercial fosaprepitant dimeglumine products revealed a significantly higher purity than expected, with all known impurities falling below specification limits. The new HPLC method has been successfully applied to analyze commercial bulk drug samples and is suitable for quality-control laboratories for both qualitative and quantitative assessment of eight related substances in the fosaprepitant dimeglumine API.