Abstract: AIM: To compare the permeation-en-hancing characters of menthol and azone on the model drug of indomethacin and to study the enhancing effect when the two agents were used in combination. METHODS: The transdermal test was conduced on the penetra-tion experiment apparatus of isolated skin.The cumulate penetrated amount, penetrating rate, stable flux and lag time were calculated upon the concentrations.RESULTS: After adding the penetration enhancer, the pen-etrating rate of indomethacin increased remarkably. It was 6.21,4.91 and 6. 92 times of that of the controls respec-tively. When used in combination, the two penetration enhancers increased much more the penetrating rate than being used separately (P <0.01).The penetration en-hancer could shorten the lag time of absorption of in-domethacin evidently. The lag time in the menthol group was shortened more evidently than that in the combined group (P <0.01).Azone had little effect on the stable flux of absorption of indomethacin, while menthol de-creased it. When the two penetration enhancerswere used in combination, distinct enhancing effect was observed.It was 2.78 and 1.38 times of that of separate agents re-spectively. CONCLUSIONS: Menthol and azone can re-markably enhance the percutaneous absorption of in-domethacin in vitro, and the enhancing effect is stron-gened when they are used in combination.

Key words: menthol, azone, indomethacin, percu-taneous absorption