Objective: To optimize formulation of self-emulsifying drug delivery systems of puerarin-soybean lecithin complex. Method: With the degree of emulsifying and particle size of emulsion droplet as indexes

oil phase

non-ionic surfactant and co-surfactant in the formulation were screened by solubility experiment and drawing phase diagram

and to determine optimum formulation. Result: Optimum formulation of the self emulsifying drug delivery system was as following:ethyloleate as oil phase

Tween-80 as nonionic surfactant and ethanol as co-surfactant

the proportion of them 5:3:2

emulsifying time 40.53 s

the average particle size 107.3 nm. Conclusion: Prepared self-emulsifying drug delivery systems of puerarin-soybean lecithin complex was yellow clear liquid

it could be a clear and transparent with light blue opalescent emulsion after adding water

and this system had good emulsifying effect without blistering.