The Simultaneous Spectral Determination of Candesartan Cilexetil and Hydrochlorothiazide in Tablets Using the Trivariate Classical Least Squares Method

Objective: Candesartan cilexetil (CDS) is a member of the sartan group of drugs and is widely used to lower blood pressure. Hydrochlorothiazide (HCT) is the most commonly used diuretic group of drugs and is prescribed together with candesartan cilexetil in cases where blood pressure cannot be reduced. Pharmaceutical preparations containing these two active compounds in combination are preferred today to provide a more effective pharmacological effect. Therefore, it is of great importance to determine the quantities of these combined pharmaceutical preparations with new analytical methods that are fast, easy, and sensitive in quality control and routine analysis. In this study, a new trivariate classical least squares calibration method (TCLS) was developed for the simultaneous quantification of candesartan cilexetil (CDS) and hydrochlorothiazide (HCT) in binary mixtures and commercial tablets without using a preliminary separation step. Material and Method: CDS and HCT compounds were kindly donated by National Pharm Ind., Turkey. HPLC-grade methanol (J.T. Baker, Netherlands) was used as a solvent for the spectrophotometric analysis. In the application of the TCLS method, the determination and quantification of CDS and HCT were carried out using UV spectrophotometric measurements with 1 cm quartz cells in the 200-310 nm spectral region (slit range 2 nm). The newly developed TCLS method was tested using a validation set consisting of eight synthetic mixture solutions within the working ranges of 4.0-20.0 μg/ml for CDS and HCT. Simultaneous quantification analyses of CDS and HCT were performed on ATACAND PLUS® Tablet supplied by Astra Zeneca İlaç Ltd Şti. Result and Discussion: The method is based on the application of TCLS to the absorbance measurements at three different wavelength points (223.5, 240.0, and 268.5 nm). The absorptivity values (µg-1mlcm-1) of pure CDS and pure HCT were 6.67x10-2, 2.76x10-2, 2.33x10-2, and 11.41x10-2, 0.46x10-2, 6.42x10-2 at the selected wavelengths, respectively. Recovery values and relative standard deviation values were calculated as 97.2% and 1.61% for CDS and 99.7% and 3.67% for HCT, respectively. This method was successfully applied to the spectrophotometric quantitative analysis of tablets containing CDS and HCT, and then, a good agreement was reported.