Transdermal delivery of tea catechins and theophylline enhanced by terpenes: a mechanistic study.
Using in vitro and in vivo techniques, terpenes were evaluated as enhancers to improve the skin permeation of therapeutically active agents derived from tea, including tea catechins and theophylline. The in vitro permeation was determined by Franz cells. The skin deposition and subcutaneous amounts of drugs sampled by microdialysis were evaluated in vivo. Terpenes varied in their activities of enhancing drug permeation. The oxygen-containing terpenes were effective enhancers of drug permeation, whereas the hydrocarbon terpenes were much less efficient. Oxygen-containing terpenes with a bicyclic structure had reduced enhancing activity. Terpenes enhanced tea catechin permeation to a much greater degree than they did theophylline. The isomers of (+)-catechin and (-)-epicatechin showed different permeation behaviors when incorporated with terpenes. In the in vivo status, terpenes promoted the skin uptake but not the subsequent subcutaneous concentration of (-)-epigallocatechin gallate (EGCG). Both increased skin/vehicle partitioning and lipid bilayer disruption of the stratum corneum (SC) contributed the enhancing mechanisms of terpenes for topically applied tea catechins and theophylline based on the experimental results from the partition coefficient and transepidermal water loss (TEWL). alpha-Terpineol was found to be the best enhancer for catechins and theophylline. The high enhancement by alpha-terpineol was due to macroscopic perturbation of the SC and the biological reaction in viable skin as evaluated by TEWL and colorimetry.
Fang
Jia-You
JY
Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Taoyuan, Taiwan. fajy@mail.cgu.edu.tw
Tsai
Tung-Hu
TH
Lin
Yu-Ying
YY
Wong
Wen-Wen
WW
Wang
Meng-Nan
MN
Huang
Jeng-Fen
JF
D000279:Administration, Cutaneous; D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D012869:Skin Absorption / Q000187:drug effects*; D013729:Terpenes / Q000494:pharmacology*; D013806:Theophylline / Q000378:metabolism*; D014867:Water / Q000378:metabolism
D013729:Terpenes; D014867:Water; D002392:Catechin; C045651:epigallocatechin gallate; D013806:Theophylline