Application of low-frequency sonophoresis (LFS) has been shown to increase skin permeability, thereby facilitating delivery of hydrophilic solutes. We have previously shown that the modified porous pathway model provides an adequate theoretical description of transdermal delivery of hydrophilic solutes through pores in the presence and absence of ultrasound. However, small hydrophilic solutes (M(w)<400 Da) that exhibit a moderate partition coefficient, K(o/w) (0.1<K(o/w)<1), may also have a substantial contribution to permeability from transport through intercellular lipid bilayers. The aim of this note is to incorporate the lipophilic pathway into the porous pathway model to describe transdermal drug transport in the absence and presence of ultrasound.
Copyright 2002 Elsevier Science B.V.