Abstract
A transdermal drug delivery system (TDDS) has attracted much attention due to several advantages over the other administration routes such as injection from the viewpoint of a less harmful method and avoiding first pass through liver. However, its real drug application has been limited to small or lipophilic drugs that can be permeated through the stratum corneum, which has a strong barrier function. Here, we focused on Solid-in-Oil-in-Water (S/O/W) emulsions as a novel TDDS carrier. This technique can encapsulate large hydrophilic molecules such as oligopeptides, proteins and DNAs in the inner oil phase of Oil-in-Water (O/W) emulsion by coating the hydrophilic macromolecules with surfactant molecules. Dispersing hydrophilic macromolecular drugs into the oil phase, S/O/W emulsion containing the hydrophilic drugs can raise the affinity and distribute to the hydrophobic stratum corneum. In this study, we encapsulated hydrophilic macromolecules into S/O/W and investigated the penetration behavior of hydrophilic macromolecules through the skin.
