Iontophoresis: fundamentals, developments and application

The skin is an excellent barrier to the transport of charged compounds and large molecules. Many substances of present and potential therapeutic utility carry charge at physiological pH, have high molecular weights and/or are hydrophilic and, consequently, do not transport well across the skin. Pathways for the transport of small ions do appear to exist through the skin and flow along these pathways can be substantially enhanced by iontophoresis.