Objective:To prepare O/W granisetron hydrochloride(GH)microemulsion of a new type transdermal delivery system.Methods:The microemulsion was prepared with the formulation containing isopropyl myristate-phosphatidyl choline-tween80-ethanol-water by the pseudo-ternary phase diagram.Quality of feedstock and adjuvant was selected as investigation factor.Dosage was selected as investigation level.The permeation steady state flux

lag time and cumulative permeation quantity of GH were selected as indices

Orthogonal tests were carried out to obtain the optimum formulation.Results:The optimum formulation of GH was A2B1C2 that IPM/Km

Km and GH were 1∶6

3∶1

5.0%.Conclusion:These results indicated that the studied microemulsion system with high osmosis acoss nude rabbits skin could be a potential vehicle for the transdermal delivery of GH.