IDENTIFICATION, ISOLATION AND CHARACTERIZATION OF PROCESS AND DEGRADATION IMPURITIES OF FUDOSTEINE AND ITS STABILITY INDICATING HPLC METHOD VALIDATION.

Fudosteine [(-)-(R)-2-amino-3-(3-hydroxypropylthio) propionic acid] is a synthetic derivative of L-cysteine, a novel expectorant. During the synthesis of Fudosteine, four process impurities were detected along with two degraded impurities in HPLC-UV analysis at a level ranging from 0.05 to 0.1%. Stress studies were conducted to assess the nature of the impurity using LCMS analysis. These detected impurities were isolated by preparative LC and a thorough study was undertaken to characterize these impurities. Based on the spectral data obtained by 1H-NMR, 13C-NMR, DEPT and 2D-NMR, Mass, elemental composition and IR, the structures were characterized as , Impuirty-I (R)-2-amino-3-mercaptopropionic acid, Impurity-II (2R,2?R)-3,3?-disulfanediylbis(2-aminopropanoic acid), Impurity-III(R)-2(3-hydroxypropyl) amino-3-3(3-hydroxypropylthio )propionic acid, Impurity-IV (R)-2-amino-3-[3-(3-hydroxypropoxy) propylthio] propionic acid, Impurity-V (R)-3-(3-hydroxypropylsulfinyl)-2-aminopropionic acid, Impurity-VI (2R,2?R)-3-3?-(propane-1,3-diyldisulfanediyl)bis(2-aminopropionic acid. The developed stability indicating RP-LC method was validated with respect to Specificity, linearity, precision, accuracy, range, robustness, ruggedness, LOD, LOQ and response factor (RF) respectively.