Validation of RP-HPLC method for determination of pH-dependent solubility of ketoconazole in phosphate buffer pH 6.8

Abstract

The solubility of ketoconazole is highly dependent on the pH of the medium. Solubility is an important physicochemical parameter needed to consider and predict to obtain the drug behavior in a physiological environment. Determination of solubility of ketoconazole in pH of intestine fluid (6-7.4) is not easy due to ketoconazole poor soluble in intestine fluid pH. The aim of this study was to validate an assay for the solubility of ketoconazole in phosphate buffer pH 6.8 using the RP-HPLC method. In addition to representing intestinal pH, phosphate buffer pH 6.8 is also generally used as an alkaline medium for the dissolution testing of several drugs. The method to analyze the solubility of ketoconazole has been developed and validated. The method was used an isocratic Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) using Phenomenex Luna (250 x 4.6 mm, 5 µm) column with a mobile phase consisting of acetonitrile: water with TEA 0.15% pH 3.3 in ratio 50:50, at the flow rate of 1 mL/min and UV detection at wavelength 232 nm. The correlation coefficients were obtained at r2=0.9997 in the range of 0.5-12 µg/mL. The recovery % ranged within 100-101%. The intra and interday RSD% were less than 1.74%. LoD was 0.15 µg/mL and LoQ was 0.45 µg/mL. According to ICH guidelines, the method was validated for selectivity, linearity, accuracy, precision, LoQ, and LoD. The proposed method is suitable for determining the solubility of ketoconazole in phosphate buffer pH 6.8.