Lateral iontophoretic solute transport in skin

Evaluation of skin barrier function using direct current III: effects of electrode distance, boundary length and shape

The objective of this study was to propose a suitable electrode disposition and shape for iontophoretic drug delivery systems in consideration of a reduction in skin barrier function and a distribution of current density. The reduction in barrier function was evaluated with our proposed method, which measured the resistance in the short term. The distribution was estimated using an electromagnetic waves analysis program. Using rectangular electrodes, effects of distance between electrodes and boundary length of the electrode on the barrier function were examined. A distance of 2 mm decreased the barrier function effectively. The barrier function was reduced with increasing electrode boundary length. Furthermore, a surrounded square type electrode was more effective in the reduction of barrier function than a paired square type. With respect to the surrounded type electrodes, both square and circle types decreased the barrier function. However, percutaneous absorption using the circle type electrode was greater than with the square type. These phenomena are attributed to not only the electrode boundary length but also the homogeneous distribution of current density. Therefore, the surrounded circle type electrode was suitable for iontophoretic transdermal drug delivery systems.

Buccal iontophoretic delivery of atenolol.HCl employing a new in vitro three-chamber permeation cell

The present work showed that the iontophoretic approach was feasible to enhance buccal drug delivery. A new in vitro horizontal three-chamber iontophoretic permeation cell has been developed to reflect the in vivo iontophoretic drug delivery more closely, electrodes were positioned on the epithelial side in separate chambers. Iontophoretic delivery of atenolol.HCl across porcine buccal mucosa increased proportional to (a) increased initial donor concentration in the range of 0.027 M to 0.10 M atenolol.HCl, (b) increased "on time" of current on/off ratio valued 50/50, 75/25 and 90/10 resulting in enhancement ratios 19, 58, and 112 respectively, initially applying 0.10 M atenolol.HCl and (c) increased current density valued 0.1, 0.2, 0.3, and 0.4 mA/cm(2) obtaining enhancement ratios 6, 18, 36, and 58 respectively, initially applying 0.10 M atenolol.HCl. Microscopy of hematoxyilin-eosin stained sections of porcine buccal mucosae conducting 8-h passive permeation showed minute morphological alterations whereas 8-h iontophoretic treatment showed disordering of the outer epithelial cell layers, alterations being more pronounced in mucosae from reference chambers than donor chambers. The results demonstrated the feasibility of the iontophoretic approach to enhance and control the rate of buccal drug delivery, hence the usefulness of the new permeation cell.