Methods and apparatus for iontophoresis application of medicaments at a

Abstract

Methods and apparatus for administering known quantities of medicaments by iontophoresis, while avoiding burns caused by extremes in the pH of the medicament medium during passage of an electric current, are disclosed. It is known that as iontophoresis progresses in conventional iontophoresis systems, the electrolysis of water occurs to produce hydrogen or hydroxyl ions at the interface of the electrode and medicament medium. Since these ions are highly mobile, they are transported directly into the skin of a patient in preference to the larger medicament ions. Thus, extreme changes in pH are experienced which result in burns due to the acidificaion or alkalinization of the medicament medium and passage of electric current through the skin. In addition, the efficiency of iontophoresis decreases over time. The present invention avoids extremes in pH by removing the hydrogen or hydroxyl ions which are created during iontophoresis and creates conditions for constant delivery over prolonged periods of time. In the present invention, the medicament ions are attached to an ion exchange matrix, such as an ion exchange resin. When the medicament leaves the ion exchange matrix, the vacated active site is filled by the produced electrolysis products, thereby allowing iontophoresis to progress at a relatively constant pH.