Transdermal iontophoresis skin alteration

Ultrasound may enhance transdermal transport by inducing skin alteration and active transport (forced convention) in the skin. Various other means of transport enhancement, including chemicals, iontophoresis and electroporation, may enhance transport synergis-tically with US. Thus, the evaluation of the synergistic effect of low-frequency US with chemical enhancers and surfactants for permeation of mannitol revealed that application of US or sodium lauryl sulfate (SLS) alone, both for 90 min, increased skin permeability about 8 and 3 times, respectively. However, the combined use of US and a 1% SLS solution increased the skin permeability 200 times to mannitol [129]. 

The remarkable resistance of the SC intercellular lipid network to the passive penetration of therapeutic agents has intensified the search for devices, chemical and physical, with the ability to perturb this lipid environment. Of the many physical techniques investigated, iontophoresis (or electrically enhanced transdermal transport) has become an important focal point [160-162]. Unparalleled in its ability to deliver (noninvasively) ionized drugs across the skin, its modus operandi appears to be largely dependent on transcutaneous ion-conducting pathways (which may be paracellular), rather than a function of direct interaction with the lipid infrastructure [163]. Nevertheless, the effect of the applied current on the lipid (and protein) domains is a matter of interest with respect to both safety considerations (i.e., does the applied current induce stmctural alterations ) and mechanistic insight. ATR-FTIR has been used in a number of studies to discern the effect of iontophoresis on SC lipid and protein structures, both in vivo and in vitro. In separate studies, human SC was examined in vivo following the delivery of current at 0.1-0.2 mA/cm for 30... 

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