EFFECT OF PENETRATION ENHANCERS (PYRROLIDONE DERIVATIVES) ON MULTILAMELLAR LIPOSOMES OF STRATUM-CORNEUM LIPID - A STUDY BY UV SPECTROSCOPY AND DIFFERENTIAL SCANNING CALORIMETRY

In order to elucidate the mechanisms of action of transdermal absorpti on-enhancing compounds, i.e., pyrrolidone derivatives (1-methyl-2-pyrr olidone, 1-ethyl-2-pyrrolidone, 1,5-dimethyl-2-pyrrolidone, 5-methyl-2 -pyrrolidone), multilamellar liposome was prepared from the simulated stratum corneum lipids and employed as a model system for the barrier function of the stratum corneum. The liposomal membrane of the stratum corneum lipid liposome (SCLL) behaves as an osmometer and has an exce llent barrier function. In addition, its phase transition temperatures are similar to those of human stratum corneum intercellular lipid reg ion. Therefore, SCLL seems to be a useful skin model. The effect of th e pyrrolidone derivatives on the osmotic behavior of SCLL was examined . As the result of the osmotic behaviors, pyrrolidone derivatives pert urb the barrier function of the liposome. The more hydrophobic enhance rs penetrate more easily into the lipid bilayer and reduce the barrier function of the membrane more effectively. The results of differentia l scanning thermograms of the SCLL suggest that the pyrrolidone deriva tives had incorporated into the lipid layer in the liposome and increa sed the fluidity of the lipid layer in the liposome and such activity might have some correlation with the transdermal absorption-enhancing activity of these compounds.