The objective of this work was to investigate how the preferred iontophoretic transport pathways of a molecule depend on its physicochemical properties. Laser scanning confocal microscopy (LSCM) was used to visualize in hairless mouse skin the distribution of two fluorescent penetrants: calcein, a multiply charged (-4), hydrophilic molecule; and nile red, a lipophilic, neutral compound. Iontophoresis and passive delivery of nile red showed that the percutaneous transport of this compound occurred via (inter- and intracellular) pathways that were clearly distinct from those followed by calcein. Although the distribution of nile red was influenced somewhat by the passage of current relative to the passive control, there was relatively little enhancement of the penetration of this compound into the skin. Calcein, on the other hand, did not passively enter the skin. However, with iontophoresis, greatly enhanced transport, with an important contribution from follicular structures, was observed. Sequential (dual) transport of the two fluorophores illustrated clearly the different pathways followed and reflected the transport and visualization studies of the individual species. It may be concluded, therefore, that the iontophoretic pathways followed across the skin are dictated by the physicochemical properties of the penetrant and by its affinity for the different environments available.

Original languageEnglish
Pages (from-to)1385-1389
Number of pages5
JournalJournal of Pharmaceutical Sciences
Issue number12
Publication statusPublished - 31 Dec 1997

Bibliographical note

Funding Information:
Financial support was provided by the U. S. National Institutes of Health (GM15585-03 and HD-27839) and by The American Foundation of Pharmaceutical Education Fellowship. We thank Lourdes Nonato, Yogeshvar Kalia, and Christopher Cullander for their help.

ASJC Scopus subject areas

  • Pharmaceutical Science


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