Comparative characterization of the physicochemical behavior and skin permeation of extruded DPPC liposomes modified by selected additives

The purpose of the present study was to analyze the influence of cholesterol (CHOL), stearylamine (SA), dicetyl phosphate (DCP), and xylenesulfonic acid sodium salt (SXS) in extruded DPPC (1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine) liposomes on their size, shape, and skin permeation of the model drug progesterone. The additives were incorporated in different molar ratios in relation to the phospholipid content. It could be proven that different molar ratios of the additives to lipids were able to modify liposome size, zeta potential, and the characteristic phase transition temperature of the lipids. In standard skin diffusion experiments SA and SXS increased the progesterone permeation two‐ to fourfold respectively after 48 h compared to the control. © 2007 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:2171-2176, 2007