Simultaneous Determination of Cilazapril and Hydrochlorothiazide in Tablets by Spectrophotometric Methods

In this study, two new spectrophotometric methods were used for the simultaneous determination of cilazapril and hydrochlorothiazide in their binary mixture. In the first method, derivative spectrophotometry, dA/dδ values were measured at 242.8 nm and 282.8 nm for cilazapril and hydrochlorothiazide, respectively, in the first derivative spectra of their combination. The relative standard deviation of the method was found to be 0.77% for cilazapril and 0.24% for hydrochlorothiazide. In the second, the absorbancy ratio method, the quantification of cilazapril and hydrochlorothiazide was performed by using the absorbances read at 210.4 nm. 250.2 nm and 270.6 nm in the zero-order spectra of their mixture; relative standard deviations of the method were found to be 1.26 % and 0.81 % for cilazapril and hydrochlorothiazide, respectively. These two methods have been successfully applied to a tablet containing these drugs.