aFaculty of Pharmacy, Department of Pharmaceutical Analytical Chemistry, University of Alexandria, El-Messalah, Alexandria, 21521, Egypt.
Two methods are described for the simultaneous determination of candesartan cilexetil (CAN) and hydrochlorothiazide (HYD) in binary mixture. The first method was based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 270 nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using chloroform: methanol (8:2, v/v) as mobile phase. Linear regression analysis data used for the regression line were in the range of 0.05–0.70 and 0.05–0.50 μg.band−1 for CAN and HYD, respectively. The second method was based on difference and derivative-difference spectrophotometry with a zero-crossing measurement technique. Linear calibration graphs of absorbance difference values (∆A) at 292 nm and 338 nm were obtained versus concentration in the range 20–100 mg.L−1 for CAN and HYD. Also linear regression equations of second derivative difference values (∆D2) at 296 nm for CAN and first derivative difference values (∆D1) at 299 nm for HYD versus concentration in the ranges 10–100 and 5– 70 mg.L−1 for CAN and HYD, respectively, were obtained. The two methods were validated according to ICH guidelines and applied on bulk powder and pharmaceutical formulation.
Candesartan cilexetil, hydrochlorothiazide, HPTLC, derivativedifference spectrophotometry, tablets
