A medical microelectrode comprises an elongate electrode body comprising a tip section, a main body section and, optionally, a coupling section. The tip section, the main body section and, optionally, the coupling section are embedded in a first electrode matrix element, which is substantially rigid, biocompatible and soluble or biodegradable in a body fluid. Additionally the microelectrode comprises a dissolution retarding layer on the first electrode matrix element and/or a second electrode matrix element disposed between the first electrode matrix element and the electrode. Upon dissolution or biodegradation of the first electrode matrix element a drug comprised by the first electrode matrix element or the second electrode matrix element is released into the tissue. Also disclosed are bundles and arrays of the electrodes and their use.