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-h accumulation from the PANi|AgCl set were 94.4 ± 81.2 μg/cm² h and 2760 ± 3980 μg/cm², respectively; those from the Ag|AgCl set were zero. For lidocaine HCl, the flux and 10-h accumulation from the PANi|AgCl set were, respectively, 43 ± 15 μg/cm² h and 392 ± 130 μg/cm²; the corresponding values from the Ag|AgCl set were 48 ± 20 μg/cm² h 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.