Transdermal iontophoresis is a potential method to administer therapeutically actigve peptides into the systemic circulation because most peptides are ineffective when taken orally~1. Especially the stability and biological activity of peptides are a concern. In this study, stability and iontophoretic transdermal permeation of two decapeptides, luteinizing hormone releasing hormone (LHRH) and Nafarelin, were evalauted. Nafarelin is an agonist analogue of LHRH: the sixth amino acid of LHRH, glycine, is replaced by D-naphthylalanine that makes the molecule more lipophilic and biologically more active.~2 The aim of this study was to evalaute the stability of LHRH and Nafarelin in buffer solution, with electrical current, and in the presence of skin metabolizing enzymes. The effect of different current profiles - direct current (DC), pulsed DC with different on/off ratios, and alternating current (AC) with differnet +/- duty cycles - on the trandermal iontophoresis of these peptides was measued. The influence of the peptides and current profile on the permeation of neutrla sugar, mannitol, during the iontophoresis was also determined.
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