In-Vitro Incompatibility Study of Valsartan and Hydrochlorothiazide by Spectroscopic and RP-HPLC Method

The present investigation was based on an in-vitro incompatibility study between valsartan and hydrochlorothiazide by spectroscopic and reverse-phase high-pressure liquid chromatography (RP-HPLC) methods. The method was developed and validated by UltraViolet-Spectroscopic (UV-Spectroscopic) method using water and methanol (4:1) as the solvent. The RP-HPLC study was carried out using Acetonitrile, methanol, and 50Mm phosphate buffer (20:50:30%) adjusted to pH-3 with orthophosphoric acid. The methods showed linearity at the concentration range of 1-5μg/ml with correlation coefficient 0.9994 for valsartan and 0.9978 for hydrochlorothiazide in the method and 5-25 μg/ml in. Both the methods were shown a percentage relative standard deviation (%RSD) values less than 2. The in-vitro incompatibility study was carried out by  UV-Spectroscopic and RP-HPLC methods. The result of the study shown that there is a change in the concentration level of both drugs in combination. The structure of the interacting compound was determined by spectral analysis using IR, 1 HNMR and LC-MS study. The spectral analysis confirmed the formation of the new complex between valsartan and hydrochlorothiazide. The result obtained from the LC-MS study also correlates 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.