Development and validation of stability indicating HPLC method for the estimation of Telmisartan related substances in tablets formulation

Abstract

A sensitive HPLC method was developed and validated for the estimation of Telmisartan related impurities in tablets formulation. The highly polar molecule requires aqueous mobile phase for the elution and separation of Telmisartan and its impurities (Impurity A, B, E and F official in EP). The developed method is found to be specific, reproducible, and stability indicating. The X-Bridge C18 150x4.6mm 3.5μ column was used and mobile phase consisted of 25mM potassium dihydrogen phosphate (KH₂PO₄) and 10mM of 1-hexaneusulphonic acid, sodium salt monohydrate buffer to achieve good resolution and retention of the analyte and its impurities. The detector linearity was established from concentrations ranging from 0.08 μg/mL to 500 μg/mL for Telmisartan and from 0.017 to 3.0 μg/mL for related impurities with a correlation co-efficient of 0.997. The relative response factor (RRF) values of impurity A, impurity E, impurity F, impurity B, TEL2, Dimer acid and Chloro analogue determined from linearity plots were 1.27, 0.43, 0.83, 1.02, 0.81, 0.80 and 0.84 respectively. The limit of detection (LOD) and limit of quantification (LOQ) found to be in the range of 0.023 μg/mL to 0.190 μg/mL for Telmisartan and impurities respectively. The molecule is forced to all stress conditions such as acid, base, oxidation, heat and photolysis as per the recommendations of ICH guidelines. All degradants are well separated from the main analyte.The method is proved to be robust with respect to change in flow rate, pH, organic phase composition and column temperature. The proposed method is found to be sensitive, precise, rapid, reproducible, and offers good column life.