Development and Validation of Reversed-Phase LC Method for Simultaneous Determination Telmisartan, Amlodipine and Their Degradation Products in Fixed Dose Combination Tablets

A simple, rapid and reproducible stability indicating RP-HPLC method was developed and validated for the simultaneous determination of telmisartan and amlodipine in binary mixture and fixed dose combination tablets. The chromatography was carried out on a 4.6 mm I.D x 250 mm, 5 μm particle size SGE make Wakosil C18-AR column with 0.025 mol L^-1 potassium di-hydrogen orthophosphate (KH2PO4) buffer (pH adjusted to 3.5 with ortho-phosphoric acid) and acetonitrile (65:35 v/v) at a flow rate of 1.0 mL min^-1 and UV detector was set at 238 nm. The developed method was validated in terms of specificity, linearity, range, accuracy, ruggedness, robustness, limit of detection and limit of quantification. The developed method shows excellent linearity over a range of 4-80 μg mL^-1 (r^2=0.9999) for telmisartan and 0.5-10 μg mL^-1 (r^2=0.9997) for amlodipine. The recoveries of telmisartan and amlodipine were 100.15% and 99.98%. The relative standard deviation (% RSD) values of intermediate precision were 0.03 and 0.39, and reproducibility were 0.32 and 0.11respectively for telmisartan and amlodipine. The limits of detection were 0.01 and 0.05, and the limits of quantification were 0.05 and 0.20 for telmisartan amd amlodipine respectively. The developed method was applied successfully for quantification of telmisartan and amlodipine in bulk drug and its fixed dose combination tablets formulations.