Effects of iontophoresis and electroporation on the stratum corneum. Review of the biophysical studies.

This review focuses on the effects induced by iontophoresis and electroporation on the stratum corneum of the skin. Hence, the aims were: (1) to contribute to the understanding of the mechanisms of drug transport by these methods; (2) to evaluate the safety issues associated with current application. Complementary biophysical methods were used to provide a complete picture of the stratum corneum. Even though the mechanism of drug transport is believed to be different, i.e., electrophoresis for iontophoresis and creation of new aqueous pathways for electroporation, the effects on the stratum corneum detected minutes after current application are very similar. For both methods, the major findings were: (1) a disorganisation of the lipid bilayers of the stratum corneum; (2) an increase in skin hydration; (3) a larger decrease in skin resistance induced by electroporation as compared to iontophoresis. These changes were partly reversible and depended on the amount of electrical charges transferred. The mechanisms of stratum corneum perturbations are discussed. These perturbations could explain partly the increase in drug transport. If iontophoresis is considered as a safe method of drug delivery, the data augurs for the safety of electroporation.