Objective:To determine the equilibrium solubility of zolmitriptan in various media and its partition coefficients for the n-octanol-water/buffer solution systems.Methods:A high performance liquid chromatography was established and used to detect the concentration of zolmitriptan;the partition coefficients for the n-octanol-water/buffer solution systems of zolmitriptan were determined by shaking flask method.Results:The equilibrium solubility of zolmitriptan in water was 12.6 g/L at 37℃.The equilibrium solubility of zolmitriptan were 1 382.0

553.0

85.2

71.5

47.1

11.5 and 4.85 g/L in buffer solutions with pH values of 3.6

4.5

6.0

6.8

7.4

8.0 and 9.0 respectively.Papp of zolmitriptan was 0.013 in water and were 0.04

0.06

0.14

0.20

0.23

0.25 and 1.44 in buffer solutions with different pH values.Conclusion:In the range of pH3.6 to pH 9.0

the equilibrium solubility of zolmitriptan was decreased while the apparent oil/water partition coefficient was increased with the increasing of pH values.