The permeation barrier of the stratum corneum is mostly composed of saturated lipids such as Ceramide Liposomeands, cholesterol, and free fatty acids. It is an effective barrier to substance exchange and prevents skin dryness.

Liposomes are spherical vesicles composed of one or more phospholipid bilayers, which are very similar to cellular membranes. Liposomes encapsulating hydrophilic or lipophilic drugs make these vesicles useful drug delivery systems.