Validated Stability Indicating RP-HPLC Method for Simultaneous Determination of Metoprolol Succinate and Olmesartan Medoxomil in Tablet Dosage Form

The present paper describes simple, rapid, reproducible, accurate and precise stability indicating HPLC method developed for quantitative simultaneous estimation of metoprolol succinate and olmesartan medoxomil in bulk and combined pharmaceutical dosage form. A chromatographic separation of both drugs was achieved with Chromasil 250 × 4.6 mm, i.d 5 μm C-18 column using methanol:0.05% v/v Ophosphoric acid in water (50:50 v/v) at the flow rate of 1ml/min. The measurements were made at 228.0 nm as detector wavelength. The described method showed excellent linearity over a range of 5-80 μg/ml for metoprolol succinate and 5-70 μg/ml for olmesartan medoxomil. The coefficient of correlation for metoprolol succinate and olmesartan medoxomil was found to be 0.9990 and 0.9993 respectively. The retention time for metoprolol succinate and olmesartan medoxomil was found to be 3.485 min and 7.085 min, respectively. The tailing factor for metoprolol succinate and olmesartan medoxomil was found to be 1.02 and 1.13 respectively. Both drugs and their combination drug product were found to be stable in neutral, thermal, oxidative and photolytic stress conditions but mild degradation was observed in acidic and alkaline conditions.