Transdermal drug delivery using electroporation. I. Factors influencing invitro delivery of terazosin hydrochloride in hairless rats

The use of electroporation pulses as a physical means of enhancing the perm eability of skin to deliver drugs is in the early stages of development. In this article, a systematic study examining the parameters influencing elec troporative transdermal delivery of terazosin hydrochloride to hairless rat skin are reported. It was found that voltage, pulse length (tau), and numb er of pulses were the three most important parameters, in that order. For c reating a significant enhancement in drug delivery to the skin, without cau sing any apparent change in its external appearance, it was necessary to de liver five or more exponentially decaying electroporation pulses, at 88 +/- 2.5 V (voltage across the skin), with a decay time constant of 20 ms. Elec trodes with larger area could attain the same voltages across the skin with a much lower applied voltage and possessed other advantages with regard to performance of the drug delivery system. (C) 2000 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 89:528-535, 2000.