Object: To investigate the solubility and Ko/w of torasemide under different pH conditions in order to provide a foundation for designing sustained-release preparations of torasemide.Methods: A series of buffer solutions and standard curves of different pH were prepared.The solubility was determined with saturation method and the value of pKa was fitted with solubility curve.Then the value of K_o/w was calculated with concentration ratio of torasemide in n-octyl alcohol and water phase.Results: The solubili...