Objective: To prepare supersaturatable self-microemulsifying drug delivery system of andrographolide for increasing its solubility and bioavailability. Method: Based on results of solubility test and pseudo-ternary phase diagrams

the formulation of self-microemulsifying drug delivery system was optimized by simplex lattice method with degree of average particle size

polydispersity index and emulsifying time as indexes;and the best supersaturated inhibitor was screened out by means of crystallization

particle size

polydispersity index

self-emulsifying time and dissolution rate of andrographolide. Result: The optimum formulation of andrographolide supersaturated self-microemulsion was ethyl oleate

polysorbate-80

polyethylene glycol 400 and hydroxypropyl methylcellulose K4M in the ration of 20:35:45:1.After emulsification

average particle size

polydispersity index

Zeta potential

emulsifying time and the cumulative dissolution rate at 1 hour of andrographolide supersaturatable drug delivery system were (29.26±0.56) nm

0.19±0.02

(-10.23±2.34) mV

(62.39±2.03) s and 91%

respectively. Conclusion: The hydroxypropyl methylcellulose K4M can obviously inhibit the crystallization time and increase the stability of the self-microemulsion;compared with the ordinary self-microemulsion

supersaturated self-microemulsion can improve the dissolution of andrographolide obviously

and the bioavailability of andrographolide is improved.