An electrode assembly for use with a drug delivery device comprises means for carrying a medicament (76), an active electrode (78) in electrical communication with the carrying means (76), at least one passive electrodes (80) and a separator pad (28) surrounding the carrying means (76). A moat region (94) is disposed between the separator pad (28) and the carrying means (76) that prevents migration of the medicament between the carrying means (76) and the at least one passive electrode (80). Means (74) for securing the electrode assembly to a surface of a patient are provided.
