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

Abstract

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 (67mM phosphate buffer, pH 7.4, I=0.17, 37°C), the individual solution of 100μM captopril and the co-binding solution with 60μM hydrochlorothiazide added were pre-equilibrated with series concentrations of HSA (10–475μM) respectively, introducing hydrodynamically into an uncoated fused silica capillary (35cm×50μm I.D. with 26.5cm 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.