Spectrofluorimetric study and detection of ketoconazole in the presence of beta-cyclodextrin

The formation of a complex between ketoconazole and beta-cyclodextrin was followed by spectrofluorimetry. The inclusion of ketoconazole in beta-cyclodextrin cavity enhanced the native fluorescence of the drug. The stoichiometry of the complex was 1:1 beta-cyclodextrin to ketoconazole and the stability constant of the complex (log K(f)) was determined to be 4.3+/-0.01 at pH=7.9 and 3.7+/-0.04 at pH=2.6. A sensitive spectrofluorimetric method for the detection of ketoconazole is presented. At optimized experimental conditions, a linear relationship between the fluorescence intensity of the solution and concentration of ketoconazole is observed in the range of 0.01-10 microg ml(-1) (5 x 10(-8) M-1.88 x 10(-5) M). The method was applied to the detection of ketoconazole in pharmaceutical products and the results were satisfactory in comparison to the official method (relative error=2.8% and standard deviation=0.06 for tablets of ketoconazole). The recovery of ketoconazole from a blood serum sample, determined by the proposed method, was 97.1+/-2.4%.