ABSTRACT:
A simple, fast, accurate and specific reverse phase high pressure liquid chromatographic (HPLC) method has been developed for simultaneous determination of Sildenafil base and its impurities in the Sildenafil Tartrate (API). Structural confirmation and characterization of Sildenafil Tartrate and its impurities was carried out by using mass spectrometry, XRD and NMR. Based on the spectroscopic studies five impurities were characterized as Impurity A- Amine, Impurity B-Nitro, Impurity C-condensed, Impurity D-CSA, Impurity E-Cyclised. The newly developed method was validated according to ICH guidelines to demonstrate specificity, precision, linearity and accuracy of the method. The proposed method enables us to determine purity of sildenafil tartrate and also the impurities associated with it in a single attempt. Mass identification has been made for the associated products during the synthesis of sildenafil tartrate. XRD study pattern reveals that polymorphic form of both citrate and tartrate salt of sildenafil are same, indicates that tartrate salt could be used as an alternate for citrate one. NMR Study pattern reveals that the formation of base peak and tartrate peak is significant in the final compound formation, of sildenafil as tartrate salt. The developed method is especially useful for routine pharmaceutical analysis.