Simultaneous Analysis of Cilnidipine and Nebivolol by Absorbance Correction Method and Q Absorption Ratio Method

Abstract

Two novel UV spectrophotometric methods have been developed for the simultaneous estimation of cilnidipine (CIL) and nebivolol hydrochloride (NBV) in combined dosage form. Method I was based on absorbance correction principle while method II was Q absorption ratio method. For absorbance correction method, λmax of CIL 242.6nm was chosen as λ1, as NBV shows nil absorbance at this wavelength and 280.6nm, the λmaxof NBV was chosen as λ2 , as both the drugs showed satisfactory absorbance at this wavelength. Beer’s law was obeyed in the concentration range of 4-48μg/mL and 4-100μg/mL for cilnidipine and nebivolol hydrochloride respectively with correlation coefficients (r2) greater than 0.990. For Q absorption ratio method, 275nm (Isosbestic point) and 280.6nm (λmax of NBV) were chosen as the two wavelengths for analysis. Beer’s law was obeyed in the concentration range of 4-48μg/mL and 4-100μg/mL for cilnidipine and nebivolol hydrochloride, respectively with correlation coefficients (r2) greater than 0.990. The developed methods were validated as per ICH guidelines. The % assays of cilnidipine and nebivolol hydrochloride in tablet dosage form were found to be 97% and 102%, respectively by absorbance correction method and 95% and 105% by Q absorption ratio method, which were within acceptance limits. The developed methods can thus serve as powerful quality control tools for simultaneous determination of cilnidipine and nebivolol hydrochloride in bulk and in combined dosage form.