The mechanism of enhancers （methanol,chloroform,azone and thiozone） was studied in vitro in mouse stratum corneum （SC）.Attenuated total reflectance Fourier-transform infrared spectroscopy （ATR-FTIR） was applied to monitor the wavenumber shifts of CH2 stretching absorbance as well as the lipid content in the SC,which were used as criteria to explain the effect of the enhancers on mouse SC.The FTIR spectra record that treatment with these four enhancers would result in significant shifts toward higher wavenumber at vasCH2 and vsCH2 and the integration areas of vasCH2 and vsCH2 decrease when treatment of methanol and choloroform.It is concluded that these four enhancers could increase the gauche conformational isomer content of lipid CH2,made the lipid in the SC a more fluid state,thus the resistance of drug transdermal delivery was reduced.
