Abstract
Four methods were developed for simultaneous determination of metoprolol and felodipine without previous separation. In the first method both drugs were determined using first derivative UV spectrophotometry, with zero crossing measurement at 222 and 235 nm for metoprolol and felodipine, respectively. The second method depends on first derivative of the ratios spectra by measurements of the amplitudes at 250.1 nm for metoprolol and 224.3 nm for felodipine. Calibration graphs are established in the range of 20-150 μg/ml and 10-60 μg/ml for metoprolol and felodipine, respectively. The third method describes the use of multivariate spectrophotometric calibration for the simultaneous determination of the analyzed binary mixture where the resolution is accomplished by using partial least squares (PLS) regression analysis. Although the components show high degree of spectral overlap, they are simultaneously determined with high accuracy and without interference of pharmaceutical dosage form excipients. A comparison with the related multivariate method of classicial least squares (CLS) analysis is done showing less relative results due to severe spectral overlap of the studied drugs. In the fourth method (HPLC), a reversed-phase column and a mobile phase of methanol:water:acetonitrile (70:22:8 v/v/v/) at 0.9 ml/min flow rate is used to separate both drugs and UV detection at 260 nm. Good linearities are obtained in concentration range of 0.15-15 μg/ml for metoprolol and 0.03-5 μg/ml for felodipine. All the proposed methods are extensively validated. They have the advantage of being economic and time saving. All the described methods can be readily utilized for the analysis of pharmaceutical formulations, the fourth method (HPLC) is successfully applied for the analysis of both drugs in human serum samples. The results obtained by adopting the proposed methods are statistically analyzed and compared with those obtained by reported methods.
Highlights
Metoprolol is a beta-adrenoceptor blocking agent used for treatment of hypertension[1]
Metoprolol was determined by measuring of its D1 amplitude at the zero-crossing point of felodipine
The D1and DD1, multivariate (CLS and Principal components regression (PCR)) and HPLC methods enable the quantitation of metoprolol and felodipine binary mixture with good accuracy and precision, either in laboratory prepared samples or in pharmaceutical dosage forms
Summary
Metoprolol is a beta-adrenoceptor blocking agent used for treatment of hypertension[1]. The most recent methods for determination of metoprolol included chromatographic[2,3,4,5], electrochemical[6,7]. Spectrophotometric[8,9,10,11,12,13] techniques. Several methods have been reported for felodipine assay including chromatographic [14,15,16] and spectrophotometric [17,18,19] techniques. Felodipine Recently, derivative spectrophotometry has been found to be a useful method in the determination of mixtures with two or more components having overlapping spectra and in eliminating interference from formulation matrix by using the zero-crossing techniques [20,21,22]. Salem,Analytical Chemistry Department, Faculty of Pharmacy, MSA University, Cairo, Egypt
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