Transdermal iontophoresis pathways

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... 

Transdermal drug delivery through iontophoresis has received widespread attention. A long-term delivery with transdermal DC voltage of <5 V was used (Phquett and Weaver, 1996). High-voltage pulses up to 200 V decaying in about 1 ms have also been used on human skin for enhancement of transport by electroporation (Phquett and Weaver, 1996). The effect was found to be due to the creation of aqueous pathways in the stratum corneum. 

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