Development and Validation of a Near-Infrared Spectroscopy Method for Quantification of the Fidaxomicin in Tablets

   A novel analytical method using reflectance NIRS combined with PLS multivariate calibration to determine fidaxomicin in tablet formulations has been developed and validated. NIR diffuse reflectance spectroscopy in reflectance mode is a versatile technique used for analyzing the optical properties of materials by combining reflection and transmission measurements. Partial least squares regression was used to establish the relationship between the IR peaks and fidaxomicin concentrations in a known standard. Metrics evaluated included correlation coefficient (R²), root mean squared error of cross-validation (RMSECV), bias, and relative percentage difference (RPD). Figures of merit, including linearity, precision, accuracy, ruggedness, selectivity, and analytical sensitivity, were assessed in accordance with ICH guidelines. Model performance was as follows: R² = 99.9, indicating excellent predictive capability; RMSECV = 4.19, reflecting low prediction error; bias 0.639; RPD 31.3. The method was validated as linear, precise, accurate, and rugged. The proposed NIR-PLS method is a viable alternative to HPLC for fidaxomicin quantification, offering advantages in speed, simplicity, cost, and environmental sustainability. By adhering to ICH guidelines, the method demonstrated reliability and applicability for routine pharmaceutical quality control.

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