Objective:To investigate equilibrium solubility and apparent oil-water partition coefficient of matrine at different pH values

and provide basis for development design of matrine liver targeting preparation. Method: Equilibrium solubility and apparent oil-water partition coefficient of matrine at pH 2~11 phosphate buffer were determined respectively

apparent solubility was determined by saturated solution method and shake-flask method

oil-water partition coefficient was calculated through mass concentration ratio of oil phase and water phase after balanced of matrine distribution

the concentration of sample liquid was determined by HPLC. Result: Matrine could dissolve in different pH solution

oil-water partition coefficient had tendency to increase with increasing of pH

it increased significantly in organic solvent

and solubility increased with polarity increasing.Solubility in water 70.26 g·L-1

oil-water partition coefficient of matrxine (lgPapp) was greater than 1.0 when pH>7.00

it could be easy to drug absorption. Conclusion: Matrine had hydrophilic and lipophilic

lipophilic was better under alkaline conditions.