ABSTRACT

In present study, three new spectrophotometric methods, original UV spectrophotometry, first and second order derivative UV spectrophotometry and a new HPLC method were developed for the determination of fexofenadine HCl (FEX) in pharmaceutical preparations. In original UV spectrophotometry, absorbances were measured at 258.7 nm in the zero order UV spectra of the solution of FEX in methanol-water (1:1) in the range of 220 - 290 nm. In first derivative UV spectrophotometry, dA/dℵ values were measured at 270.4 nm in the first derivative UV spectra of the solution of FEX in methanol-water (1:1) in the range of 245 - 285 nm (Δℵ= 2 nm). In second derivative UV spectrophotometry d²A/dℵ² values were measured at 252.84 nm in the second derivative UV spectra of the solution of FEX in methanol-water (1:1) in the range of 245 - 285 nm (AX= 2 nm). Linearity range was found as 100.0 - 1000.0 ug/mL in all the spectrophotometric methods. Mean recoveries and the relative standard deviations of the methods were found as 99.55 % and 1.10 % in original UV spectrophotometry, 100.97 % and 1.09 % in first derivative UV spectrophotometry and, 99.25 % and 1.10 % in second derivative UV spectrophotometry respectively. In HPLC method, an isocratic system consisted of an ACE C18 analytical column and a mobile phase composed of methanol - phosphate buffer (pH 3.0, 0.1 M) (95:5, v/v) at a flow rate 1.0 mL/min was used for the optimal chromatographic separation using UV detection at 220 nm. Diflucortolone valerate was used as internal standard. Mean recoveries and the relative standard deviations was found as 100.23 % and 0.54 % in HPLC method. All the methods developed were successfully applied to five tablet formulations commercially available in Turkish drug market and the results were compared statistically with each other.