Controlled transdermal iontophoresis by ion-exchange fiber

The objective of this study was to assess the transdermal delivery of drugs using iontophoresis with cation- and anion-exchange fibers as controlled d rug delivery vehicles. Complexation of charged model drugs with the ion-exc hange fibers was studied as a method to achieve controlled transdermal drug delivery. Drug release from the cation-exchange fiber into a physiological saline was dependent on the lipophilicity of the drug. The release rates o f lipophilic tacrine and propranolol were significantly slower than that of hydrophilic nadolol. Permeation of tacrine across the skin was directly re lated to the iontophoretic current density and drug concentration used. Ani on-exchange fiber was tested with anionic sodium salicylate. The iontophore tic flux enhancement of sodium salicylate from the fiber was substantial. A s the drug has to be released from the ion-exchange fiber before permeating across the skin, a clear reduction in the drug fluxes from the cationic an d anionic fibers were observed compared to the respective fluxes of the dru gs in solution. Overall, the ion-exchange fibers act as a drug reservoir, c ontrolling the release and iontophoretic transdermal delivery of the drug. (C) 2000 Elsevier Science B.V. All rights reserved.