Abstract: A device based on iontophoresis and intended for transdermal dosing of an active agent, said device comprising a pair of electrodes (11,12), which can be connected to a direct-current source, and two chambers (13, 14), separated from each other, the first chamber (13) containing the active agent, each chamber having a porous membrane (15, 16) on the side facing the individual's skin, and the first chamber (13) being divided in two sections (13a, 13b) in such a manner that the first chamber section (13a) is in contact with the electrode (11) and the second chamber section (13b) is in contact with the membrane (15) coming into contact with an individual's skin, wherein between the chamber sections (13a and 13b) is a membrane (18) selectively permeable either to cations or to anions, the first chamber section (13a) containing an electrolyte and the second chamber section (13b) containing the ionic active agent, bound to a ion exchanger therein, which in turn preferably comprises fibres and ion exchanging grou