A New Stability Indicating Reverse Phase HPLC Method for the Determination of Related Substances of DPP4 Inhibitor Drug: Linagliptin

A simple, sensitive, selective and reproducible stability indicating reverse phase HPLC method has been developed and validated for the determination of related substances of linagliptin drug substance. Separation of impurities was carried out on a YMC Pack ODS-AQ, 5 μm (250 × 4.6 mm) column. Column eluent consists of gradient mixing of phosphate buffer at pH-3.7 as mobile phase A and a mixture of acetonitrile, methanol and water in the ratio of 600:250:150 v/v/v as mobile phase-B. Gradient elution at a flow rate of 1.0 mL/min and injection volume is 10 μL. The UV/vis detector is set to a wavelength of 226 nm and the column oven is set at 30 ºC. The detector response was found to be linear over the concentration range of 0.07-1.1 μg/mL with correlation coefficients greater than 0.999 for linagliptin and its related substances. LOD values for specified impurities range from 0.004-0.005% w/w and LOQ values from 0.013-0.015% w/w. The accuracy obtained by the proposed method was found to be in the range of 93.2-101.3%. Degraded and process impurities are well separated and the method has been validated for specificity, precision, ruggedness, linearity, accuracy and robustness as per ICH guidelines.