Abstract
Transdermal drug delivery systems attract much attention due to several unique advantages over other administration routes. The transdermal delivery, however, has been known to be limited to the delivery of low molecular weight drugs. Delivery of hydrophilic drugs through the skin is generally difficult due to the hydrophobic property of the skin surface. Based on the Solid-in-Oil (S/O) technique, hydrophilic drugs including proteins were coated with hydrophobic surfactant molecules to form surfactant-protein complexes. These complexes could be easily dispersed in an oil-base solution which has a permeation-enhancing effect. The main function of the new system is to promote hydrophilic drug penetration through the hydrophobic skin barrier, mainly due to stratum corneum. This approach is unique in that it is based on a non-aqueous vehicle for transdermal hydrophilic drug delivery.
