In vitro incompatibility study of Valsartan and Hydrochlorothiazide by spectroscopic and RP-HPLC Method

Abstract

The present investigation is based on an <em>in vitro </em>incompatibility study between valsartan and hydrochlorothiazide by spectroscopic and reverse-phase high-pressure liquid chromatography (RP-HPLC) methods. The method has been developed and validated by ultraviolet (UV) spectroscopic method using methanol and water (1:4) as the solvent. The RP-HPLC study has been carried out using acetonitrile, methanol and 50 Mm phosphate buffer (20:50:30 %) adjusted to pH 3 with orthophosphoric acid. The methods show linearity at the concentration range of 1-5 μg/ml with correlation coefficient 0.9994 for valsartan and 0.9978 for hydrochlorothiazide in the concentration range of 1-5 μg/ml. Both the methods have shown a percentage relative standard deviation values less than 2. The <em>in vitro </em>incompatibility study has been carried out by UV-spectroscopic and RP-HPLC methods. The results of the study show that there is a change in the concentration level of both drugs in combination. The structure of the interacting compound has been determined by spectral analysis using IR, ¹H NMR and LC-MS study. The spectral analysis confirms the formation of the new complex between valsartan and hydrochlorothiazide. The results obtained from the LC-MS study also correlate the reason behind an increase in the concentration of valsartan and decreases the concentration of hydrochlorothiazide during recovery study by spectroscopic and RP-HPLC method.