Abstract

Quantitative determination of two anti-hypertensive drugs in their combined dosage form by spectrophotometric and high pressure liquid chromatographic methods

Author(s): Khadiga M.Kelani, Abdallah A.Shalaby, Magda Y.Elmaamly, Michael K.Halim

In this study determination of Telmisartan (TELM) and hydrochlorothiazide (HCT) were conducted by application of Spectrophotometry and Hi- Performance-Liquid-Chromatography (HPLC). Four different accurate, sensitive and reproduciblemethods were applied for the simultaneous determination of (TELM) and (HCT) in their bulk powder and pharmaceutical dosage form. The firstmethod ismulti-wavelength analysis inwhich two wavelengths were selected for each drug in such a way that the difference in absorbance was zero for the second drug. At wavelengths 274.2 nm and 308.6 nm TELM had equal absorbance values; therefore, these two wavelengths have been used to determineHCT; on a similar basis 300 nmand 321 nm were selected to determine TELM. The second method is Q-analysis (graphical absorbance ratio) method involve the formation of Q-absorbance equation using the respective absorptivity values at 280 nm (ISO-absorptive point) and 274 nm(ë max of HCT). The third method is mean centering of ratio spectra (MCR) with measurement at 302.2 nm and 338.8 nm for TELM and HCT respectively. The fourth method is an isocratic reversedphase HPLC procedure using amobile phase 0.05Mammoniumacetate (pH 6.0): acetonitrile:methanol (30:45:25) with detection at 274 nmon an CSCINERTSILODS C18 column (5 um particle size, 150 mm length x 4.6 mm internal diameter) at a flowrate 1.2 ml/min. The suggested procedureswere checked using laboratory prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed methods was further assessed by applying the standard addition technique. The results obtained by applying the proposed methods were statistically analyzed and compared with a reported method.