Application of capillary electrophoresis-frontal analysis for comparative evaluation of the binding interaction of captopril with human serum albumin in the absence and presence of hydrochlorothiazide

The application of capillary electrophoresis-frontal analysis for comparative evaluation of the binding interaction between antihypertensive drug captopril and human serum albumin in the absence and presence of diuretic drug hydrochlorothiazide was presented in this work. At near-physiological conditions (67 mM phosphate buffer, pH 7.4, I=0.17, 37 degrees C), the individual solution of 100 mu M captopril and the co-binding solution with 60 mu M hydrochlorothiazide added were pre-equilibrated with series concentrations of HSA (10-475 mu M) respectively, introducing hydrodynamically into an uncoated fused silica capillary (35 cm x 50 mu m I.D. with 26.5 cm effective length). The values of number of binding sites, the binding constant for captopril and hydrochlorothiazide binding to HSA were obtained, respectively. It can be found that both drugs exhibit moderate binding properties towards HSA and there does not exist significant competitive binding effects between them. (C) 2015 Elsevier B.V. All rights reserved.