Abstract:
A simple, accurate, precise and stability Indicating RP-HPLC method was developed and
validated for simultaneous estimation of metoprolol succinate and olmesartan medoxomil
in bulk and tablet dosage form. The RP-HPLC method has shown adequate separation for
metoprolol succinate and olmesartan medoxomil from its degradation products. The
separation was achieved on a Phenomenex luna ODS C18 (250mm X 4.6mm i.d., 5μm
particle size) with an isocratic mixture of acetonitrile: 50mM phosphate buffer pH 4.0
adjusted with glacial acetic acid in the ratio of 55:45 v/v. The mobile phase at a flow rate
of 1.0ml/min, Injection volume 20μl and wavelength of detection was kept at 225nm. The
retention time for metoprolol succinate and olmesartan medoxomil was 2.451±0.1min and
6.167±0.1min, respectively. The linearity of the proposed method was investigated in the
range of 5-50μg/ml and 2-20μg/ml for metoprolol succinate and olmesartan medoxomil,
respectively. Correlation coefficient was 0.999 and 0.9996 for metoprolol succinate and
olmesartan medoxomil, respectively. The limit of detection was 0.2847μg/ml and 0.1251μg/ml for metoprolol succinate and olmesartan medoxomil, respectively and the
limit of quantification was 0.8630μg/ml and 0.3793μg/ml for metoprolol and olmesartan,
respectively. Force degradation study was carried out on combined dosage form as per
ICH guideline and it was exposed to hydrolysis (acid and base hydrolysis), oxidative and
thermal conditions to apply stress. Proposed methods were validated as per ICH guidelines
for linearity, accuracy, precision, specificity and robustness for estimation of metoprolol
succinate and olmesartan medoxomil in commercially available tablet dosage form and
results were found to be satisfactory. Thus the developed and validated stability indicating
method can be used successfully for marketed formulations.