Ion-exchange fibers and drugs: a novel device for the screening of iontophoretic systems.

The objective of this study was to theoretically model and experimentally measure the extent of drug release from ion-exchange fibers. The release was measured as a function of current density and NaCl concentration using a novel iontophoretic cell. The fibers tested contained weak carboxylate (-COOH) ion-exchange groups. The cationic model drugs tacrine and metoprolol were chosen on the basis of previous research, where tacrine had the lowest release rate and metoprolol the highest release rate. An in-house designed three compartment test cell was developed to test the suitability of drugs for iontophoretic drug delivery. In this cell, the anode and the drug containing ion-exchange fiber compartments were separated with a Nafion ion-selective membrane, while the fiber and the return electrode compartments were separated with a porous membrane. Tacrine proved to be a good drug candidate for this system as the release of the tacrine from the device was controllable with salt concentration and current density. Metoprolol release from the device was, however, not controllable.