TRANSDERMAL IONTOPHORETIC DELIVERY OF ARGININE-VASOPRESSIN .2. EVALUATION OF ELECTRICAL AND OPERATIONAL FACTORS

In vitro iontophoretic delivery of arginine-vasopressin (AVP) across the rat skin was carried out to explore various electrical and operational factors of pulsed D.C. iontophoresis as well as their effect on the enhancement of skin permeation of AVP. The skin permeation rate was found to be a linear function of the density of pulse current and the duration of application. By varying the current input rate, mode of application and buffer capacity, the desirable rate of skin permeation could be obtained. The skin permeation was observed to return to passive diffusion after the termination of iontophoresis treatment. It generally required approx. 1.5-2 h of iontophoresis treatment for AVP permeation to reach steady state. It was demonstrated that AVP can be delivered transdermally by consecutively applying, stopping and reapplying the electric field alternatively. The effect of the frequency of pulse current on the in vitro skin permeation by iontophoresis was found to be negligible and the reason for the observation was analyzed. © 1990.