Abstract:Major advantages of transdermal drug delivery system (TDDS) include avoiding of drug degradation in hepatic and gastrointestinal, predetermining release rate and blood drug level, reducing administration frequency and adverse reactions, and increasing patient compliance. But its application was limited by stratum corneum barrier and low skin permeability of drugs. Terpene penetration enhancers are low toxic and can improve the skin permeability and enhance the permeating veloc both of hydrophilic and lipophilic drugs. Terpenes can also significantly enhance the cumulative release amount of drug at its low concentration comparing with other synthetic penetration enhancers, and play an important role in the TDDS. This review presented the source, classification, mechanism and applications of terpenes, combined use with other enhencers and methods. Optimization, evaluation and prospective applications of terpene penetration enhancers were also discussed.