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Lateral iontophoretic solute transport in skin
P M Lai1, Y G Anissimov, M S Roberts
1Department of Medicine, University of Queensland, Princess Alexandra Hospital, Brisbane, Australia.
Pharmaceutical Research
|February 9, 1999
Summary
Iontophoresis delivers solutes like sodium, ethanolamine, and lidocaine laterally through skin. Solute concentration decreases exponentially with distance due to microcirculation clearance, reaching baseline levels.
Area of Science:
- Pharmacokinetics and Drug Delivery
- Biophysics
- Dermal Transport
Background:
- Iontophoresis facilitates transdermal drug delivery.
- Understanding lateral solute movement is crucial for optimizing drug distribution.
Purpose of the Study:
- Investigate the lateral iontophoretic transport of sodium, ethanolamine, and lidocaine.
- Determine solute concentration changes in tissues relative to electrode distance.
Main Methods:
- Anodal iontophoresis was performed on an in vivo rat model.
- Radiolabeled solutes were used, and tissue concentrations were measured via liquid or gamma counting.
- Tissues were dissected at 1 cm intervals between electrodes.
Main Results:
- Solute concentrations decreased exponentially with lateral distance from the active electrode.
- Lateral transport was limited to <2 cm for ethanolamine and lidocaine.
- Sodium exhibited a greater drift velocity than ethanolamine or lidocaine.
Conclusions:
- Lateral solute diffusion is primarily limited by microcirculatory clearance.
- Concentration gradients diminish with distance, reaching baseline levels similar to contralateral tissues.