A simple, isocratic, specific and sensitive stability-indicating high-performance liquid chromatographic method was developed and validated for the determination of fimasartan in synthetic mixture. Fimasartan is used to treat hypertension. Reverse phase chromatography was performed on Shimadzu LC-20AD pump (binary) and Shimadzu PDA-M20A Diode Array Detector using Hypersil BDS C18 column (250 x 4.6 mm, 5?m) mobile phase containing Phosphate buffer pH3 :Acetonitrile (50:50, v/v) with a flow rate of 1ml/min. Detection was done at wavelength 262nm. Linearity was observed in the concentration range of 5-30?g/mL (R2=0.999) with regression equation y=78487x+66095. The LOD was found to be 1.54?g/ml and LOQ was found to be 4.67?g/ml. Fimasartan was subjected to stress conditions such as acidic, alkaline, oxidation, photolysis and thermal degradations. The proposed method was validated as per ICH guideline and was found to be accurate, precise and specific. The degradation products peaks were well resolved from the standard drug peak and hence this method can be used for quality control of fimasartan. The drug showed significant degradation in alkaline and oxidative condition. Degradation products in alkaline and oxidative conditions were identified by LC-MS. Oxidative degradation followed first order kinetic. Degradation rate constants and half -lives were determined.
