Transdermal and intradermal iontophoretic delivery of dexamethasone sodium phosphate: quantification of the drug localized in skin

Abstract

In this study, the effect of iontophoresis on the transdermal and intradermal delivery of dexamethasone sodium phosphate (DEX-P) was examined in vitro and in vivo in the hairless rat model by skin permeation studies, tape stripping, and skin extraction. Cathodal or anodal iontophoresis (ITP) was performed and samples were analyzed by HPLC. In vitro experiments revealed that cathodal ITP significantly enhanced the cumulative amount of DEX-P permeating through the skin when compared to passive and anodal delivery. Tape stripping and skin extraction studies performed in vivo after ITP showed enhanced deposition of the drug in the stratum corneum and underlying skin when compared to passive delivery. The DEX-P and DEX depot formed in the stratum corneum and underlying skin were retained for at least 48 h and 24 h, respectively. In conclusion, ITP demonstrated potential as a feasible enhancement technique to drive the drug into and through the skin in significant amounts as compared to passive delivery.

Keywords::

• Intradermal delivery
• transdermal delivery
• iontophoresis
• dexamethasone sodium phosphate
• tape stripping

Acknowledgments

This research was funded by Transport Pharmaceuticals Inc., Framingham, MA. The helpful suggestions and proofreading by Ms. Yi-Ying Yu are highly appreciated.