Transdermal delivery of macromolecules using skin electroporation

Purposes. (1) To evaluate the feasibility of transdermal delivery of macromolecules by skin electroporation. (2) To assess the influence of the molecular weight of the permeant on transport and examine whether there exists a "cur-off" value of molecular weight. (3) To localize the transport pathways of the macromolecules in the skin. Methods. FITC-dextran (FD) of increasing molecular weight (4.4, 12 and 38 kDa) were used as model macromolecules to study the extent of transport across hairless rats skin in vitro and to localize their distribution in the skin by confocal scanning laser microscopy. Results. Electroporation enhanced the transport of the macromolecules as compared to passive diffusion. The transdermal delivery by skin electroporation of FITC and FD 4.4 was equivalent whereas transport of higher molecular weight FD was lower but significant. FITC and FD 38 were observed in the epidermis both around and in the keratinocytes. Conclusions, Transdermal and topical delivery of macromolecules of at least 40 kDa can be achieved by skin electroporation.