Stability-indicating spectrophotometric and spectrofluorimetric methods for determination of alfuzosin hydrochloride in the presence of its degradation products.

Validated stability-indicating spectrophotometric and spectrofluorimetric assays (SIAMs) were developed for the determination of alfuzosin hydrochloride (ALF) in the presence of its oxidative, acid, and alkaline degradation products. Three spectrophotometric methods were suggested for the determination of ALF in the presence of its oxidative degradation product; these included the use of zero order (0D), first order (1D), and third order (3D) spectra. The absorbance was measured at 330.8 nm for (0D) method, while the amplitude of first derivative (1D) method and that of third derivative (3D) method were measured at 354.0 and 241.2 nm, respectively. The linearity ranges were 1.0-40.0 microg/ml for (0D) and (1D) methods, and 1.0-10.0 microg/ml for (3D) method. Two spectrofluorimetric methods were developed, one for determination of ALF in the presence of its oxidative degradation product and the other for its determination in the presence of its acid or alkaline degradation products. The first method was based on measuring the native fluorescence of ALF in deionized water using lamda(excitation) 325.0 nm and lamda(emission) 390.0 nm. The linearity range was 50.0-750.0 ng/ml. This method was also used to determine ALF in human plasma with the aid of a suggested solid phase extraction method. The second method was used for determination of ALF via its acid degradation product. The method was based on the reaction of fluorescamine with the primary aliphatic amine group produced on the degradation product moiety. The reaction product was determined spectrofluorimetrically using lamda(excitation) 380.0 nm and lamda(emission) 465.0 nm. The linearity range was 100.0-900.0 ng/ml. All methods were validated according to the International Conference on Harmonization (ICH) guidelines, and applied to bulk powder and pharmaceutical formulations.