The Effect of Iontophoresis with and without Electroporation on the Penetration of High Molecular Compounds into the Stratum Corneum.

Both iontophoresis (IP) and electroporation (EP) can be utilized to increase the penetration of relatively high molecular pharmaceutical and/or cosmeceutical compounds into the stratum corneum (SC), the uppermost layer of the skin. However, few reports exist on which molecular weights are capable of penetrating the SC, although low molecular compounds of less than 500 Da have been found to readily permeate the skin barrier. In our investigation, we applied fluorescein amine-labeled sodium hyaluronate to porcine aural skin after treatment by IP alone or EP + IP. Each layer of the SC was then tape stripped several times. The stripped SC sheets were observed using a confocal laser scanning microscope to determine the relative amounts of sodium hyaluronate present. The results confirmed that the molecular weight of sodium hyaluronate that penetrated the SC was higher with EP + IP than with IP alone. A high correlation was also established between the quantity of sodium hyaluronate that penetrated and its molecular weight following combined EP + IP treatment.