Katsuhiro Nakamura

Transdermal administration of salmon calcitonin by pulse depolarization-iontophoresis in rats

Using the pulse depolarization-iontophoresis (PDP-IP) system, salmon calcitonin (sCT), a drug for the treatment of osteoporosis, was transdermaly administered in rats. While absorption of sCT was not observed after passive transdermal administration, the serum sCT concentration was confirmed at a dose of 0.2-4 microg when the PDP-IP system was employed. The results indicated that PDP-IP could enhance transdermal absorption of peptide drugs. Also noted was the increased amount of absorption of sCT along with an increase in the dose. We investigated the influence of electrical parameters (current, frequency) in PDP-IP on the transdermal absorption of sCT. An optimal current for drug absorption was found within the range of transported current (0.1-1.0 mA) employed for PDP-IP. In comparison with the results obtained at 0.1 mA, the drug absorption increased, along with an increase in transported current, when the current was set at 0.5 mA, while the drug absorption decreased at 1.0 mA in comparison. The decrease in drug absorption was assumed to be attributable to the structural destruction of skin by application of excessive current. There was no change in skin resistance attributable to the frequency; nor was there any influence of the frequency on the amount of drug absorption.