A practical assessment of transdermal drug delivery by skin electroporation

Transdermal drug delivery has many potential advantages, but the skin's poo rly-permeable stratum corneum blocks delivery of most drugs at therapeutic levels. Short high-voltage pulses have been used to electroporate the skin' s lipid bilayer barriers and thereby deliver compounds at rates increased b y as much as four orders of magnitude. Evidence that the observed flux enha ncement is due to physical alteration of the skin by electroporation, as op posed to only providing an iontophoretic driving force, is supported by a n umber of different transport, electrical and microscopy studies. Practical applications of electroporation's unique effects on skin are motivated by l arge flux increases for many different compounds, rapidly responsive delive ry profiles, and efficient use of skin area and electrical charge. Greater enhancement can be achieved by combining skin electroporation with iontopho resis, ultrasound, and macromolecules. Sensation due to electroporation can be avoided by using appropriate electrical protocols and electrode design. To develop skin electroporation as a successful transdermal drug delivery technology, the strong set of existing in vitro mechanistic studies must be supplemented with studies addressing in vive/clinical issues and device de sign. (C) 1999 Elsevier Science B.V. All rights reserved.