Chromatographic determination of clotrimazole, ketoconazole and fluconazole in pharmaceutical formulations

High-performance liquid chromatographic technique has been developed for the determination or some azolcsantifungals namely, clotrimazole (CZ), ketoconazole (KZ) and fluconazole (FZ), in pure forms and in pharmaceutical formulations. The proposed HPLC-method can be successfully applied as a stability indicating method for the determination of CZ in presence of its acid degradation products; viz (2-chlorophenyl)-diphenyl methanol and imidazole. The analyzed drugs were separated on a reversed-phase column [Bondapak C18 (10 microm, 25 cm x 4.6 mm, i.d.)] using a mobile phase containing acetonitrilc+25 mM trishydroxymeihyl aminomethane in phosphate butter (pH 7) = 55:45 (v/v), with UV-detection at 260 nm. The differences in the retention times (tR) of the three azoles permit their use as internal standard for each other. In addition, a coupled TLC-densitometric method has been also applied as a stability indicating method to separate and quantify CZ alone or in presence of byproducts impurities and/or its acid degradation products. The TLC-fractionation was performed on a precoated silica gel F254 plates using a solvent system consisting of chloroform+acetone+ammonia (25%) (7:1:0.1, by volumes), CZ was well separated from its acid degradation products and quantified by densitometric scanning at 260 nm.