Spectrophotometric determination of amlodipineand nicardipine in pharmaceutical formulations viabinary complex formation with eosin Y

A validated simple and selective spectrophotometric method was developed for the selective determination of amlodipine and nicardipine in bulk powders and pharmaceutical formulation. The proposed method was based on the formulation of a binary complex between either of the studied drugs and eosin Y in aqueous buffered medium. The surfactant, methylcellulose, was added to enhance the solubility of the formed complex. The binary complexes showed absorption maxima at 549 nm. The different experimental parameters affecting the development of stability of the colors were studied and optimized. Under the optimum reaction conditions, linear relationship with good correlation coefficients (0.9981 and 0.9995) were found between the absorbances and the concentrations of amlodipine and nicardipine respectively in the range of 5-60 µg/ml for both drugs. The limits of detection were 1.8 and 1.2 µg/ml while the limits of quantitation were 6.0 and 3.6 µg/ml for both drugs respectively. The analytical parameters were fully validated and results were satisfactory. No interference was observed from the excipients that are commonly present in pharmaceutical formulations. The proposed method was successfully applied to the analysis of the cited drugs in some pharmaceutical formulations. The mean percentage recoveries were 100.04 ± 0.83 and 99.98 ± 0.80. The results obtained are reproducible with a coefficient of variation less than 2% and were in good agreement with those obtained using the reference methods.