Determination of solubility and oil-water partition coefficient of linarin

Objective To establish a method for determination of solubility and oil-water partition coefficient of linarin,and to provide the basis for drug evaluation and dosage form design.Methods Equilibrium solubilities were determined by HPLC method in different organic solvents and different pH buffer solution systems;Also the solubilities of linarin in certain macromolecules and surfactant were measured;Molinspiration software was used to forecast the oil-water partition coefficient of linarin,and the partition coefficients of linarin in n-octanol-water/buffer solution systems were measured by shake flask-HPLC method.Results The equilibrium solubility of linarin in water was 0.059 μg/mL,which was lower than that in alkaline solution;Certain macromolecules and surfactant could increase the solubility of linarin,especially HP-β-CD with 214.6-fold increase;The octanol-water partition coefficient of linarin was between 0.50 and 1.04,consistent with the computer predicted 0.513.Conclusion Linarin is insoluble in water,and poor fat-soluble,but its solubility could be improved by adding accessories.