A Novel Ultra-High Performance Liquid Chromatography Method for the Determination of Erdosteine, Related Impurities and Degradation Products in New Effervescent Tablets

A novel and automated, stability-indicating, reversed phase ultra performance liquid chromatography (UPLC) method was developed and validated for the quantitative determination of erdosteine, its known impurities and two novel degradation products in a new pharmaceutical dosage form (effervescent tablets). The chromatographic separations were performed on a Waters Acquity UPLC HSS T3, 1.8 µm (2.1 mm × 150 mm, I.D.) stainless steel column. The mobile phase consisted of 0.1% TFA in water and methanol under gradient elution conditions, at a flow rate of 0.29 mL/min, for the assay and impurities analysis. UV detection was set at a wavelength of 238 nm. Erdosteine raw material, placebo and effervescent tablets were subjected to forced degradation. The new degradation products (labeled OX1 and OX2) were found after oxidative treatment and characterized by ultra performance liquid chromatography mass spectrometry. The validation parameters such as linearity, limit of detection (LOD) and quantification (LOQ), accuracy, precision, specificity and robustness were highly satisfactory for all analyzed compounds. LOD (0.020 and 0.011–0.385 µg/mL for erdosteine and impurities, respectively) and LOQ values show the high sensibility of the method. Specificity of the method was confirmed by testing the matrix components. The validated method demonstrated to be suitable for routine quality control purposes and for routine stability studies of erdosteine in effervescent formulations.