Determination of equilibrium solubility, apparent oil/water partition coefficient and dissociation constant of antigout drug SE-10

objective To establish a method for determination the content of SE-10, determinate its physicochemical constants, and provide theoretical basis for the development of preparations. Methods High performance liquid chromatography method was established to measure equilibrium solubility, apparent oil/water partition coefficient of SE-10 at 37 ℃in buffer solution at various p H. The p Ka was determined by UV method. Results The equilibrium solubility of SE-10 increased with increase in p H, and apparent oil/water partition coefficient decreased inversely. Equilibrium solubility was 237.1μg·m L-1and log P was 1.68 when the p H was 7.0. The p Ka calculated by UV absorbance was 4.34. Conclusions SE-10 is slightly soluble. Appropriate dissociation constant and lipophilicity of SE-10 suggest that it would be absorbed easily by intestine, and this provides the theoretical basis for development of SE-10 oral preparation.