Preparation of O/W microemulsion and measurement of skin irritation of microemulsion

Adopting isopropyl myristate,isopropyl palmitate,and soybean oil as different oil phase materials,Tween 80 blended with lecithin as surfactant as well as ethanol and 1,2-propylene glycol as different co-surfactant,O/W(microemulsions) were prepared respectively.In accordance with the area of the microemulsion regions in the pseudo ternary phase diagram,the effect of the ingredients on the formation of microemulsion region was studied and the kind and blending ratio of the ingredients were screened and identified.The type of the microemulsion was identified by measurement of the(electrical) conductivity of the microemulsion.Experimental results showed that,in order to form rather big area of the(microemulsion) region,isopropyl palmitate is to be used as oil phase;the optimal mass ratio of Tween 80 to lecithin is 2∶1;while ethanol is to be used as co-surfactant.Through animal skin test,the O/W microemulsion is confirmed satisfactory in aspects of non-poisonous and non-irritation.Such O/W microemulsion is suitable for using as carrier for skin penetration topical pharmaceuticals.