Transdermal Drug Delivery by Iontophoresis: Mechanistic Aspects

Abstract

Iontophoresis involves the delivery of ionic drug molecules under electric fields.The drug molecules will be taking the least resistance pathways such as hair follicles.There are two components to the iontophoretic delivery, electrorepulsion, and electroosmosis.J lontophoresis = J electrorepulsion ± J electrosmosis Electrorepulsion is the simple repulsive force between similar charges.Electroosmosis is the convective solvent flow in the direction of the anode to cathode because of the current passage.Burnette and Ongpipattanakul hypothesized that skin is negatively charged at pH 7.4.They observed that electroosmosis is changed by altering the membrane electrical properties by preferential binding of cations to the fixed negative charges in the membrane. [1]lectroosmosis facilitates the passage of cationic species but inhibits the anionic species.Electroosmosis can be used to deliver polar and neutral solutes.The relative importance of electrorepulsion and electroosmosis depends on the physicochemical and electrical ABSTRACTThe passive diffusion of drugs in transdermal delivery is hindered by the stratum corneum and limits the scope of deliverable molecules through the skin.The evolution of novel electrical and physical enhancement techniques can enable the delivery of hydrophilic and larger molecules such as proteins and peptides through the skin.Iontophoresis utilizes small amounts of direct current to push charged drug molecules through and across the skin.Several drug categories have been investigated over the years as possible drug candidates for this mode of delivery.It enables the delivery of more hydrophilic molecules in contrast to conventional transdermal delivery and has an advantage of modulating the rate of delivery by changing the electrical parameters.