(371c) Iontophoretic Transdermal Drug Delivery System Using a Conducting Polymeric Membrane

This work investigated the application of a porous polyaniline (PANi) membrane as a conducting polymeric membrane as well as an electrode in an iontophoretic transdermal drug delivery (TDD) system. Model drugs studied were: caffeine (MW: 194.2), lidocaine HCl (MW: 270.8) and doxycycline HCl (MW: 480.1). The PANi membrane was first tested as a simple membrane between the donor and receptor solutions; it provided satisfactory permeation profiles; the observed flux values were well described by a simplified mass transport model. A mouse skin was then mounted beneath the PANi film; such a composite system also presented satisfactory permeation profiles. Iontophoretic TDD experiments were next performed using both Ag|AgCl electrodes and PANi|AgCl electrodes for comparison; a PANi anode replaced the Ag anode in the last set. For doxycycline HCl, the flux and the 24-hour accumulation from the PANi|AgCl set were 94.4±81.2μg/cm² hr and 2760±3980μg/cm² respectively; those from the Ag|AgCl set were zero. For lidocaine HCl, the flux and 10-hour accumulation from the PANi|AgCl set were respectively 43±15μg/cm² hr and 392±130 μg/cm²; the corresponding values from the Ag|AgCl set were 48±20μg/cm² hr and 348±78 μg/cm². Porous polyaniline membrane appears to be capable of replacing the Ag part of Ag|AgCl electrode system; further such a membrane can exercise additional control over agent transport rate. Aqueous-organic partitioning system through the porous membrane of PANi was tested with this novel technique as well. Because of the rather low porosity of the synthesized PANi film, such a system did not yield a high permeation rate.