Simultaneous determination of fexofenadine and its related compounds by HPLC

A simple reversed phase liquid chromatographic (RPLC) method has been developed and subsequently validated for the determination of fexofenadine hydrochloride and its related compounds A and B. The method utilizes a C8 column for the separation and determination of meta-isomer (related compound B). The separation was achieved using an Eclipse XDB C8, 5μm, 4.6×150 mm column and a mobile phase comprising 1% triethylamine phosphate (pH 3.7), acetonitrile and methanol in the ratio 60:20:20 (v/v/v). 5-Methyl 2-nitrophenol has been used as internal standard for the purpose of quantitation of fexofenadine. The described method was linear over a range of 0.7–18.7 μg/ml for related compounds A and B and 60–750 μg/ml for assay of fexofenadine. The relative standard deviation ( n=3) was 0.5% for the drug and 3.4% for related compounds. The intermediate precision was 0.79% ( n=9) for assay and 5.16% ( n=9) for related impurities. The mean recovery of both the related compounds were in the range of 94–103%. Limits of detection (LOD) and quantification (LOQ) for the related compounds A and B were 0.18, 0.12 and 0.56, 0.48 μg/ml, respectively. The precision of the method was checked by F-test using a reported method as reference and the calculated value (1.35) was found to be less than the table value at 95% confidence levels. The obtained results confirm that the method is highly suitable for its intended purpose.