The effect of electroporation on iontophoretic transdermal delivery of calcium regulating hormones

Electrically-assisted delivery by iontophoresis and/or electroporation was used in vitro to deliver the calcium regulating hormones, salmon calcitonin (sCT) and parathyroid hormone (1-34) (PTH) through human epidermis. Such d elivery could be useful for chronic treatment of post-menopausal osteoporos is and other clinical indications as a superior alternative to parenteral d elivery, sCT (50 mu g/ml) or PTH (1-34) (100 mu g/ml) formulation was prepa red in citrate buffer (pH 4.0 or 5.0, respectively). Epidermis separated fr om human cadaver skin was used, Iontophoresis was applied using a constant current power source and electroporation with an exponential pulse generato r. Silver/silver chloride electrodes were used. A combination of electropor ation and iontophoresis resulted in higher transdermal permeation than eith er one technique alone. Electroporation also shortened the lag time of iont ophoretic transdermal delivery of salmon calcitonin. Pulsing at lower volta ges followed by iontophoresis did not result in increased transport (over i ontophoresis alone), perhaps because the transdermal voltage was very low. The transdermal transport of salmon calcitonin by pulsing with 15 pulses (1 ppm) of 500 V (200 ms) followed by iontophoresis led to a quick input and high flux. The average transdermal voltage was only about 50 V for a 500 V study. (C) 2000 Elsevier Science B.V. All rights reserved.