Transdermal drug delivery enhanced and controlled by erbium : YAG laser: acomparative study of lipophilic and hydrophilic drugs

The influence of an erbium:YAG laser on the transdermal delivery of drugs a cross skin was studied in vitro. Indomethacin and nalbuphine, which have th e same molecular weight, were selected as model lipophilic and hydrophilic drugs, respectively, to compare skin permeation by laser treatment. The res ults indicate a significant increase in the permeation of indomethacin and nalbuphine across skin pretreated with an erbium:YAG laser. The laser had a greater effect on the permeation of hydrophilic molecules which usually po ssess low permeability. The laser intensity and its spot size were found to play an important role in controlling transdermal delivery of drugs. Perme ation of the hydrophilic drug increased following an increase of laser ener gy. On the other hand, a different result was observed for the lipophilic d rug transported across laser-treated skin. The stratum corneum (SC) layer i n skin could be partly, ablated by the erbium:YAG laser. The barrier functi on of the SC may also be modulated by a lower intensity of the laser withou t affecting the viability and structure of the epidermis/dermis as determin ed by histological observations. However, ultrastructural alteration of the epidermis/dermis may be caused by laser treatment. Use of an erbium:YAG la ser is a good method for enhancing transdermal absorption of both lipophili c and hydrophilic drugs, because it allows precise control of SC removal, a nd this ablation of SC can be reversible to the original normal status. (C) 2001 Elsevier Science BY All rights reserved.