Related Experiment Videos
Pore charge distribution considerations in human epidermal membrane electroosmosis
S K Li1, A H Ghanem, W I Higuchi
1301 Skaggs Hall, Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah 84112, USA. kevin.li@m.cc.utah.edu
Journal of Pharmaceutical Sciences
|October 9, 1999
Summary
This study investigated transdermal electroosmosis in human epidermal membrane (HEM). At high voltages, HEM pores behave as if they are only negatively charged, validating a simplified model for iontophoresis.
Area of Science:
- Biophysics
- Materials Science
- Pharmacology
Background:
- Transdermal drug delivery utilizes iontophoresis, a process influenced by electroosmosis.
- Understanding the charge characteristics of human epidermal membrane (HEM) pores is crucial for optimizing iontophoresis models.
- The Nernst-Planck model is a key tool for predicting transdermal transport.
Purpose of the Study:
- To evaluate if a model assuming solely net negative charges in pores adequately describes transdermal electroosmosis in HEM at neutral pH.
- To determine if this simplified pore charge model enhances the predictive power of the modified Nernst-Planck model for transdermal iontophoresis.
- To gain insights into the pore charge distribution within HEM.
Main Methods:
- Electroosmosis experiments were conducted on synthetic polycarbonate membranes and HEM.
- Radiolabeled urea, mannitol, and water were used as model permeants.
- Experiments were performed at both low (<=0.5 V) and high (>=1.0 V) applied voltages, under anodal and cathodal conditions.
Main Results:
- Synthetic membranes validated the electrokinetic theory with a single negative pore charge assumption.
- Low voltage experiments on HEM showed significant pore charge distribution, deviating from the single charge model.
- High voltage experiments on HEM were consistent with pores possessing only net negative charges.
Conclusions:
- A simplified model of solely net negative charges in HEM pores is insufficient at low voltages due to complex charge distribution.
- At higher voltages, where field-induced pore formation occurs, the simplified model of net negative charges in HEM pores is validated.
- This finding supports the use of a simplified pore charge model for transdermal iontophoresis under specific high-voltage conditions.