Kinetics of the acidic and enzymatic hydrolysis of benazepril HCl studied by LC

A reversed-phase high-performance liquid chromatographic (HPLC) method was developed and validated for the kinetic investigation of the chemical and e nzymatic hydrolysis of benazepril hydrochloride. Kinetic studies on the aci dic hydrolysis of benazepril hydrochloride were carried out in 0.1 M hydroc hloric acid solution at 50, 53, 58 and 63 degrees C. Benazepril hydrochlori de appeared stable in a pH 7.4 phosphate buffered solution at 37 degrees C and showed susceptibility to undergoing in vitro enzymatic hydrolysis with porcine liver esterase (PLE) in a pH 7.4 buffered solution at 37 degrees C. Benazeprilat appeared to be the major degradation product in both (chemica l and enzymatic) studies of hydrolysis. Statistical evaluation of the propo sed HPLC methods revealed their good linearity and reproducibility. Relativ e standard deviation (R.S.D.) was less than 4.76, while detection limits fo r benazepril hydrochloride and benazeprilat were 13.0 x 10(-7) and 9.0 x 10 (-7) M, respectively. Treatment of the kinetic data of the acidic hydrolysi s was carried out by non-linear regression analysis and k values were deter mined. The kinetic parameters of the enzymatic hydrolysis were determined b y non-linear regression analysis of the data using the equation of Michaeli s-Menten. (C) 2002 Elsevier Science B.V. All rights reserved.