Transdermal iontophoresis of sodium nonivamide acetate I. Consideration of electrical and chemical factors

Transdermal iontophoresis is a process which enhances skin permeation of ionized species by an electrical field as driving force. The aim of this present study was to investigate the transdermal iontophoresis of a newly designed capsaicin derivative, sodium nonivamide acetate (SNA). Studies of electrical and physicochemical factors acting on the kinetics of in vitro iontophoresis were performed. Iontophoresis increased the transdermal penetration flux of SNA as compared to the passive diffusion in this study. Several application modes which possessed the same electrical energy had been researched. The iontophoretic flux of SNA increased following the decrease of donor buffer pH values. This trend could be due to the physiological property of skin and electro-osmotic flow presented. Comparing the various application modes, the discontinuous on/off cyclic current mode showed higher penetration capacity than did continuous mode which was due to the intensity of effective current which would not decay for on/off cyclic application of iontophoresis. The result of the present study is particularly helpful in the development of a SNA transdermal iontophoretic delivery system.