Quantitative study of electrophoretic and electroosmotic enhancement during alternating current iontophoresis across synthetic membranes.
One of the primary safety and tolerability limitations of direct current iontophoresis is the potential for electrochemical burns associated with the necessary current densities and/or application times required for effective treatment. Alternating current (AC) transdermal iontophoresis has the potential to eliminate electrochemical burns that are frequently observed during direct current transdermal iontophoresis. Although it has been demonstrated that the intrinsic permeability of skin can be increased by applying low-to-moderate AC voltages, transdermal transport phenomena and enhancement under AC conditions have not been systematically studied and are not well understood. The aim of the present work was to study the fundamental transport mechanisms of square-wave AC iontophoresis using a synthetic membrane system. The model synthetic membrane used was a composite Nuclepore membrane. AC frequencies ranging from 20 to 1000 Hz and AC fields ranging from 0.25 to 0.5 V/membrane were investigated. A charged permeant, tetraethyl ammonium, and a neutral permeant, arabinose, were used. The transport studies showed that flux was enhanced by increasing the AC voltage and decreasing AC frequency. Two theoretical transport models were developed: one is a homogeneous membrane model; the other is a heterogeneous membrane model. Experimental transport data were compared with computer simulations based on these models. Excellent agreement between model predictions and experimental data was observed when the data were compared with the simulations from the heterogeneous membrane model.
Yan
Guang
G
Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 30 S 2000 E, Skaggs Hall 213, Salt Lake City, Utah 84112, USA. g.yan@utah.edu
Li
S Kevin
SK
Peck
Kendall D
KD
Zhu
Honggang
H
Higuchi
William I
WI
D004553:Electric Conductivity; D004586:Electrophoresis / Q000379:methods; D007478:Iontophoresis / Q000379:methods*; D008567:Membranes, Artificial; D008962:Models, Theoretical; D009995:Osmosis
D008567:Membranes, Artificial