An electrode assembly for use in an iontophoresis device for the transcutaneous administration of an active therapeutic species has a base layer of including a linking conductive base material which is consumed (oxidizes or reduces) preferentially to water, a first upper layer of sacrificial material coated on a first portion of the base layer wherein the sacrificial material is consumed preferentially to the linking conductive base material of the base layer. A second upper layer of non-conducting material is coated on a second portion of the base layer, the second upper layer being spaced from the first upper layer, connected by a narrow exposed linking area of the base layer material remaining exposed therebetween. During operation of an associated iontophoresis device, the sacrificial material will be sequentially consumed; the first upper layer will be fully consumed followed by the linking conductive base material of the exposed linking area of the base layer which severs the base layer thereby breaking circuit continuity disabling activity in the device. A visual indicator may be provided allowing a wearer to monitor the state of reaction of the linking area.