ISOLATION, CHARACTERIZATION OF DEGRADATION PRODUCTS OF SITAGLIPTIN AND DEVELOPMENT OF VALIDATED STABILITY-INDICATING HPLC ASSAY METHOD FOR SITAGLIPTIN API AND TABLETS

The degradation pathway of sitagliptin in bulk and tablet has been investigated during stress study. Major degradation products were isolated in pure form and characterized using mass and NMR spectroscopy. Three previously unreported impurities were found to be, 3-(trifluoromethyl)-6, 7-dihydro[1,2,4] triazolo[4, 3-a] pyrazin-8(5H)-one, (2E)-1-[3-(trifluoromethyl)-5, 6-dihydro[1, 2, 4] triazolo[4, 3-a] pyrazin7(8H)-yl]-4-(2, 4, 5-trifluorophenyl) but-2-en-1-one and (3E)-1-[3( trifluoromethyl)-5,6-dihydro[1,2,4] triazolo[4, 3-a] pyrazin-7(8H)-yl]-4( 2, 4, 5-trifluorophenyl) but-3-en-1-one. Further, a stability-indicating reverse phase HPLC assay method was developed on Poroshell 120 ECC18 (3X150mm, 2.7 mu) column using mobile phase consisting of 5mM ammonium acetate and acetonitrile with gradient elution in presence of spiked degradation products and impurity. The flow rate was 0.5ml/min and detection was at 210nm. The method was found to be linear over 10 ae g-500 ae g/ml (r(2)>0.999). The method was validated with respect to accuracy, precision, specificity, robustness and found to be stability indicating.