Human calcitonin delivery in rats by iontophoresis.

In-vitro ionotophoresis (0.33 mA cm-2) of calcitonin (50 micrograms mL-1, pH 4) was performed with the hairless rat skin model. Direct current was as potent as pulse current (2.5 kHz on/off 1/1) iontophoresis in promoting transdermal permeation of calcitonin. Increase in duration of current application from 20 min to 1 h did not increase calcitonin flux. Results suggest that calcitonin can be blocked in the skin pores through which it travels or can accumulate in the skin and be progressively released from the depot. In-vivo experiments showed that transdermal iontophoretic administration of calcitonin induced a hypocalcaemic effect in rats.