An in vivo investigation of the rabbit skin responses to transdermal iontophoresis

To optimize the benefits of transdermal iontophoresis, it is necessary to d evelop a suitable animal model that would allow for extensive assessments o f the biological effects associated with electro-transport. Rabbit skin res ponses to iontophoresis treatments were evaluated by visual scoring and by non-invasive bioengineering parameters and compared with available human da ta. In the current density range 0.1 1.0 mA/cm(2) applied for 1 h using 0.9 % w/v NaCl and 0.5 mA/cm(2) for up to 4 h, no significant irritation was ob served. 2 mA/cm(2) applied through an area of 1 cm(2) for 1 h resulted in s light erythema at both active electrode sites but without significant chang es in transepidermal water loss (TEWL) and laser Doppler velocimetry (LDV). A value of 4 mA/cm(2) under similar conditions caused moderate erythema at the anode and cathode with TEWL and LDV bring significantly elevated at bo th sites; 1 mA\cm(2) current applied for 4 h, caused moderate erythema at b oth anode and cathode; and 1 mA/cm(2) applied for 1 h caused no irritation when the area of exposure was increased from 1 to 4.5 cm(2). When significa nt irritation and barrier impairment occurred, the erythema was resolved wi thin 24 h with barrier recovery complete 3-5 days post-treatment. Rabbit sk in thus shows promise as an acceptable model for iontophoresis experiments. (C) 2000 Elsevier Science B.V. All rights reserved.