A Multivariate curve resolution approach to the study of the degradation kinetics of valsartan under photolytic and acid conditions

Abstract

The analysis of UV-spectrophotometric data with second-order chemometrics techniques, including multivariate curve resolution with alternating least-squares (MCR-ALS) and hybrid hard- and soft MCR (HS-MCR), was examined as an alternative tool for studying the kinetics of drug degradation under stress conditions, employing valsartan (VAL) as a model drug. Despite small structural and spectroscopic differences between VAL and its degradation products, MCR-ALS and HS-MCR were able to detect the generation of two photoneutral degradation products (DP-1 and DP-2) and a single acid hydrolysis product (DP-3), providing good approximations to their pure spectra and concentration profiles, from which estimations of the kinetic profiles and rate constants were obtained. Kinetic models based on first-order reactions explained the degradation processes. MCR-ALS and HS-MCR analyses yielded similar rate constants; however, the latter was capable of more properly fitting the experimental data to a kinetic model in the case of drug photolysis. The results were confirmed by comparison with data obtained by HPLC analysis of the degraded samples.