Area under the curve and ratio difference spectrophotometric methods with evaluation of the greenness for simultaneous determination of olmesartan medoxomil and metoprolol succinate

The aim of this study is to develop and validate two simple spectrophotometric methods for simultaneous determination of metoprolol succinate (MET) and olmesartan medoxomil (OLM) in tablet form. Method (I) was area under the curve (AUC) method. This approach involved the measuring of the area over a variety of wavelengths. Two wavelength ranges; 213-230 nm and 244-266 nm were chosen for determination of MET and OLM, respectively. Method (II) was ratio difference spectrophotometric method. For determination of MET, the ratio spectra were generated using 15 & mu;g/mL OLM as a divisor then the peak to trough amplitudes between 221 nm and 245 nm were displayed versus the corresponding concentrations of MET. For determination of OLM, the peak-to-peak amplitudes between 247 and 293 nm were chosen and found to be directly proportional to OLM concentrations using 15 & mu;g/mL MET as a divisor. The linearity ranges were 2-30 & mu;g/mL and 2-25 & mu;g/mL for MET and OLM, respectively. The assay results showed good mean %recovery & PLUSMN; SD as well as good agreement with that of the reported method. The developed methods were validated according to ICH guidelines. The developed methods are accurate, precise, eco-friendly and could be applied successfully to estimate OLM and MET in their combined dosage form.