Development and validation of spectrophotometric and ion pair chromatographic techniques for estimation of telmisartan and hydrochlorothiazide

Abstract

Ultraviolet spectrophotometric and ion pair chromatographic methods have been developed forsimultaneous estimation of telmisartan and hydrochlrothiazide from their tablet dosage form. The firstmethod involves multiwavelength spectrophotometric estimation (Method 1) where interference dueto hydrochlrothiazide at 286 nm (wavelength for estimation of telmisartan) was eliminated byrecording absorbance difference at 286 nm and 308 nm whereas interference of telmisartan at 262 nm(wavelength for estimation of hydrochlrothiazide) was removed by recording absorbance differenceat 262 nm and 282 nm. Linearity of the response was demonstrated by telmisartan in theconcentration range of 5-35 μg/ml with a square correlation coefficient (r2) of 0.9995. Linearity ofthe response was demonstrated by hydrochlrothiazide in the concentration range of 3-21 μg/ml with asquare correlation coefficient (r2) of 0.9992. The second method utilizes ion pair chromatography(Method 2) on a HIQ sil ODS column (250 mm length x 4.6 mm internal diameter) using methanol:0.0025 M orthophosphoric acid (70:30 by volume pH 4.6) containing 0.1% 1-hexane sulphonic acidmonohydrate sodium salt as mobile phase with UV detection at 259 nm over a concentration range of20-120 μg/ml for telmisartan and 12.5-75 μg/ml for hydrochlrothiazide. Losartan potassium was usedas the internal standard. Both the methods were applied successfully for the analysis of the two drugsfrom their tablet dosage form. The results of analysis were validated statistically and as per ICHQ2Bguidelines. The developed methods are simple, selective and reproducible and can be applied forroutine analysis of formulations containing telmisartan and hydrochlrothiazide.