Dissolution tests of benazepril-HCl and hydrochlorothiazide in commercial tablets: comparison of spectroscopic and high performance liquid chromatography methods

Simple, rapid and reliable spectroscopic methods (absorbance ratio and Vier ordt) were compared with HPLC for quantitative determination in dissolution tests of benazepril-HCl (BNZ) and hydrochlorothiazide (HCT) in commercial tablets. A 249 nm wavelength was chosen as the isosbestic point in the abso rbance ratio method, and the absorbance ratios A(236)/A(249) nm for BNZ and A(269)/A(249) nm for HCT were used for calculation of regression equations . For the Vierordt method, A(1)(1) values (% 1.1 cm) obtained at 236 and 26 9 nm for both substances were used for quantitative analyses of BNZ and HCT . In the HPLC method, simultaneous determination of BNZ and HCT from dissol ution medium was achieved using the mobile phase containing phosphate buffe r (0.01 M, DH 6.2) and acetonitrile (65:35) on a Supelcocil LC-18 (4.6 x 25 0, 5.6 mm) reversed phase column. Dissolution tests of commercial tablets w ere carried out according to USP XXII paddle method in 0.1 N HCl at 50 rpm at 37 +/- 0.5 degreesC. Comparison of the dissolution data from the HPLC an d two spectroscopic methods indicated that spectroscopic and HPLC methods w ere in good correlation with each other. Therefore, it was concluded that b oth spectroscopic methods as well as HPLC can be used in routine analyses o f BNZ and HCT in dissolution tests of commercial tablets. (C) 2000 Elsevier Science S.A. All rights reserved.