EFFECTS OF PHOSPHOLIPIDS ON THE IN-VITRO PERCUTANEOUS PENETRATION OF PREDNISOLONE AND ANALYSIS OF MECHANISM BY USING ATTENUATED TOTAL REFLECTANCE FOURIER-TRANSFORM INFRARED-SPECTROSCOPY

We investigated the effects of 10 phospholipids on the in vitro percut aneous penetration of prednisolone (PR) through the dorsal skin of gui nea pigs. A marked enhancing effect of PR penetration was observed in the presence of phospholipids that have unsaturated acyl chains. A max imum of 68-fold enhancement was observed compared to that of control. On the contrary, phospholipids that have saturated acyl chains did not significantly increase the amount of PR passing to the receptor side. Attenuated total reflectance-Fourier transform infrared spectroscopy was used to monitor the outer several microns of stratum corneum (SC) surface. It was observed that phospholipids that have unsaturated acyl chains induced higher and broader absorbance shifts in the C-H bond s tretching region while phospholipids that have saturated acyl chains i nduced lower and sharper absorbance shifts in the C-H bond stretching region. A significant parallel between the amount of PR penetrated and the lipid-chain fluidity of the SC was found. These results suggest t hat phospholipids may influence the percutaneous penetration of PR by changing the lipid-chain fluidity of the SC.