Iontophoresis: Skin Permeation Enhancement and Applications

Abstract

Transdermal drug delivery (TDD) systems offer a number of potentialadvantages over conventional methods such as injectable and oraldelivery as they avoid the first pass metabolism and increase thepatient’s compliance. However, a major limitation of TDDs is that theskin is highly impermeable to macromolecules and hydrophilic drugs.The main barrier of drugs across the skin is the skin outermost layer,the stratum corneum. Application of electricity via the skin is one ofthe methods extensively used for enhancing drugs or chemicalsubstances through the skin. In this article, iontophoresis, a methodfor enhancing the skin permeation of hydrophilic drugs, macromolecules,and charged substances is reviewed. The article alsoelaborates on mechanisms that iontophoresis enhances skinabsorption which include electromigration, electroosmosis andpassive permeability. Factors affecting TDD systems usingiontophoresis including electric current, physicochemical properties ofdrug and physical properties of the skin are also discussed.Keywords:iontophoresis, skin permeation enhancement, factorsaffecting skin permeation