Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry


Validated Spectrophotometric Methods for Simultaneous Determination of Lercanidipine HCl and Enalapril MALEATE in their Binary Mixture

Author(s): Hanan A Merey, Nesrin K Ramadan, Sherine S Diab, Azza A Moustafa

Four, simple, accurate, precise, sensitive and rapid spectrophotometric methods were employed for the simultaneous determination of Lercanidipine HCl (LER) and Enalapril Maleate (ENA) in their binary mixture. Method (A), dual wavelength, depended on measuring absorbance difference (ΔA) between 225.8 and 241.2 nm for determination of ENA (ΔA of LER is zero at the same two wavelengths). Method (B), second derivative spectrophotometry, adopted for the determination of ENA by measuring the peak amplitude of second derivative at 221.0 nm (zero crossing of LER). Method (C), absorptivity factor, based on determining the total concentration at 220.8 nm, where the absorptivity of LER is double the absorptivity of ENA. In methods (A), (B) and (C), the determination of LER was achieved directly by measuring its absorbance at λmax 358.6 nm. Method (D), mean centering, based on measuring the mean centered ratio spectra of LER and ENA at 292.0 and 210.0 nm, respectively. The specificity of the proposed methods was tested by analyzing laboratory prepared mixtures of both drugs in different ratios and their combined dosage form (Zanipress® tablets). The validity of the developed methods was further assessed by applying the standard addition technique. Statistical comparison revealed that there was no significant difference between the results obtained from the proposed methods and those obtained by official or reported ones in terms of accuracy and precision.