OBJECTIVE:To investigate effects of ethylene/vinyl acetate copolymer(EVAc) membrane with various weight fraction rate of
vinyl acetate,different membrane thickness and different
skin permeation enhancers on levonorgestrel
Permeation rate through human skin.METHODS:The Valia Chien permeation cells and HPLC were used to determine the permeation of LNG in 70% ethanol saturated solution under the above different conditions.RESULTS:The permeation rate of LNG through EVAc membrane covered human skin showed a zero order permeation kinetics,with rate increased as increasing the weight fraction of vinyl acetate in the copolymer(280 g·kg -1 >180 g·kg -1 >140 g·kg -1 ),but decreased as increasing the thickness of membrane.The permeation rate was proportional to the reciprocal of the membrane thickness(r=0.992 9).Enhancers(20 g·kg -1 oleicacid and 20 g·kg -1 azone) can further increase the permeation of LNG.CONCLUSION:The skin permeation rate of LNG can meet the requirement with 20 g·kg -1 OA and proper EVAc member(50 μm,280 g·kg -1 VAc).