Document Type: Research article
1- School of Pharmacy, East China University of Science and Technology, Shanghai 200237, PR China. 2- Department of Chemistry, Tsinghua University, Beijing 100084, PR China.
Engineering Research Center of Modern Preparation Technology of TCM (Ministry of Education), Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China.
Department of Chemistry, Tsinghua University, Beijing 100084, PR China.
School of Medicine, Tsinghua University, Beijing 100084, PR China.
The aim of the present study was to investigate the influence and the mechanisms of cineole
and terpineol on the in-vitro transdermal delivery of huperzine A from microemulsions, and
their potential synergistic effect on the permeation enhancement. The transdermal delivery
of huperzine A from microemulsions with different concentrations of cineole and terpineol
through the rat abdominal skin was determined by Franz-type diffusion cells. The partition
coefficient of huperzine A between the full thickness skin and microemulsion was determined.
Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was carried
out to analyze the effects of cineole and terpineol on the biophysical properties of the stratum
corneum (SC) and the mechanisms of permeation enhancement. These results indicated that
cineole and terpineol could synergistically increase the transdermal delivery of huperzine A
from microemulsions through increasing the partition and diffusion coefficients of huperzine
A. ATR-FTIR studies further validated the synergistic effect and revealed that the enhancing
mechanisms were due to increasing the disorderliness and fluidity of SC lipid alkyl chains,
disrupting the structure of keratin in SC, and extracting SC lipids. In conclusion, cineole and
terpineol, acting synergistically to enhance the transdermal delivery of huperzine A from
microemulsions, might provide an alternative permeation enhancer combination for the
transdermal delivery of huperzine A.