EFFECT OF MOLECULAR WEIGHT OF PENETRANTS ON IONTOPHORETIC TRANSDERMAL DELIVERY In Vitro

Transdermal delivery is preferable for some drugs to oral administration or intravenous injection. Macromolecules such as peptide drugs, however, little penetrate through the skin. Iontophoresis is an effective transdermal method for macromolecules. In this study the effect of duration of applying electric field and degree of current density has been investigated under in vitro conditions. The macromolecules whose molecular weights are over 1.0×10 Dalton have been thought not to quickly penetrate the viable skin by passive diffusion, even if the drugs could pass through stratum corneum by applying the advanced transdermal techniques (Tojo, 2003). The viable skin may become, therefore, a significant barrier layer to the macromolecules.