Determination of Solubility and Apparent Oil/Water Partition Coefficient of Sitafloxacin / 医药导报

ABSTRACT

Objective To determine the solubility and apparent oil/ water partition coefficient of sitafloxacin in different solvents. Methods High performance liquid chromatography (HPLC) was used. The column was Dikma Diamonsil C18 (2) (4. 6 mmí250 mm,5 μm). The mobile phase was 0. 05 mol·L-1 KH2 PO4 solution (pH was adjusted with H3 PO4 to 2. 4)-acetonitrile (7030). The column temperature was set at room temperature. The flow rate was 1. 0 mL·min-1 . The detection wavelength was 295 nm and the injection volume was 10 μL. The solubility of sitafloxacin and the apparent oil/ water partition coefficient at pH 2. 0,4. 3,5. 8,6. 6,7. 4,8. 0,10. 0 and 11. 2 were determined. Results The equilibrium solubility of sitafloxacin in water was 0. 44 mg·mL-1 and the apparent oil/ water partition coefficient was 0. 23 (lgP= -0. 64) at (37±2) ℃ . Sitafloxacin has the lowest equilibrium solubility (0. 13 mg·mL-1 ) and the highest apparent oil/ water partition coefficient in pH7. 4 buffer solution system. At pH>10 and pH<5. 8,the solubility of sitafloxacin increased obviously and apparent oil/ water partition coefficient decreased. Conclusion Sitafloxacin is insoluble in water and also poorly soluble in oil,but its solubility could be improved significantly in acidic or alkaline solution.