Abstract: AIM: To investigate the enhancement of ethanol onPercutaneousPereation and topical anaesthesia of tetracaine gel.METHODS: Tetracaine (4 %,w/w)gels werePrepared by using 20 %and 70 %ethanol asPenetration enhancers.Franz diffusion chamber and UV spectrophotometry were adopted in the transdermal osmotic test of isolated mouse skin.Von Frey test was used to evaluate the topical anesthetic effect of tetracaine gels.RESULTS: 20 % and 70 % ethanol greatly improved thePercutaneousPermeation of tetracaine gel (P<0.05).Penetration rates were 1.53 -2.12 times over that of tetracaine gel withoutPenetration enhancer.Statistical analysis indicated that tetracaine gel with 70 % ethanol was better than that with 20 %ethanol (P<0.01),however,thelag timeProlonged.Von Frey test demonstrated that the maximumPain restrainPercentage of tetracaine gel with 70 %ethanol reached 113 % after its one-hour topical use and the duration anaesthesia was five hours.CONCLUSION: Tetracaine gel containing 70 % ethanol may become a new formulation with idealPercutaneousPermeation and topical anesthetic effect.

Key words: pharmacology, tetracaine, ethanol, penetration enhancers, topical anaesthesia, transdermal delivery