Abstract: Effects of pH , donor phase concentration and surfactants on skin permeation in vitro were investigated using excised rat skin. Percutaneous absorption rate of dihydro etorphine hydrochloride(DHE) was increased in the of pH 5, pH 3, pH 7 and pH 9. When the DHE concentration was from 20 to 80 μg/ml, the permeation rate at different concentrations was ratherstable at pH 7 and 9, but was intricated at pH 3 and 5.Skin penneation treated with1, propanediol, Azone, and 3% menthol in 50% ethanol solution increased the permeability of DHE by 1.16, 1.95, 4.86 times , respectively.

Key words: Percutaneous absorption, Dihydro etorphine hydrochloride, Wistar rat, Azone, Menthol