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 absorption-enhancing compounds, i.e., pyrrolidone derivatives (1-methyl-2-pyrrolidone, 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 excellent barrier function. In addition, its phase transition temperatures are similar to those of human stratum corneum intercellular lipid region. Therefore, SCLL seems to be a useful skin model. The effect of the pyrrolidone derivatives on the osmotic behavior of SCLL was examined. As the result of the osmotic behaviors, pyrrolidone derivatives perturb the barrier function of the liposome. The more hydrophobic enhancers penetrate more easily into the lipid bilayer and reduce the barrier function of the membrane more effectively. The results of differential scanning thermograms of the SCLL suggest that the pyrrolidone derivatives had incorporated into the lipid layer in the liposome and increased 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.