The effect of two atones on the lateral lipid organization of human stratum corneum and its permeability

Purpose. Investigation of the relationship between changes in human SC lipi d organization induced by N-alkyl-azocycloheptane-2-one and SC permeability to the model compound HgCl2. Methods. Human dermatomed skin was treated with propylene glycol (PG), oley l-Azone (OAz) or dodecyl-azone (DAz) in 0.15 M PG. Untreated skin served as control. The lateral lipid organization was studied by electron diffractio n. Hg was measured on tape-strips by Xray microanalysis and in the acceptor phase by atom absorption spectrometry. Results. In control and PG treated samples, the lipid packing was mainly or thorhombic, while a small fraction was hexagonal. In OAz and DAz treated sa mples, the orthorhombic lipid organization remained, however, the hexagonal packing was recorded less frequently. The amount of Hg decreased as a func tion of depth in all SC samples, however, the penetration profile increased significantly upon OAz treatment. The cumulative amount of Hg in the accep tor phase of OAz treated samples also increased significantly compared to c ontrol and PG treated samples. Conclusions. The increased penetration of Hg into OAz treated skin could no t be related to an orthorhombic-hexagonal phase transition. Alternatively, phase separation of OAz and/or formation of grain boundaries might affect S C permeability, hereby increasing Hg penetration. A similar mechanism is pr oposed for DAz.