Stability-Indicating HPLC-DAD Method for the Determination of Linagliptin in Tablet Dosage Form: Application to Degradation Kinetics.

This work aims to develop HPLC-DAD method for linagliptin (LNG) quantitation in the presence of its degradation products in tablets and to study its degradation kinetics. LNG samples were extracted from tablets and diluted. Various ICH degradation conditions were applied to study LNG degradation kinetics. LNG was assayed by a C18 column using a simple isocratic mobile phase (methanol:water containing 0.3% TEA, 40:60, pH 4.5) pumped at 1 mL/min. The drug was detected at 225 nm. The method showed high linearity (r2 > 0.999) with CV% and % error of the mean <2% over the range of 1-50 μg/mL. Limits of detection and quantitation were 0.3 and 1.0 μg/mL, respectively. LNG retention time was 11 min with a total run time of 17 min. In all degradation conditions applied, LNG was well separated from its degradation products. The method was successfully used to quantitate LNG content in its tablets and study its degradation kinetics in acidic, alkaline and oxidative forced degradation experiments. In conclusion, simple, precise and reliable method for the separation and determination of LNG in the presence of its degradation products under different stress conditions was developed and validated according to the latest ICH guidelines.