A percutaneously-insertable catheter (10) for administering an active agent to a body site, the catheter comprising: a distal portion (22) expandable from a contracted condition of introduction to a deployed administering condition, to stabilize the distal end (2) of the catheter (10) at the body site of administration, and—a flexible tubular element (16) coupled to said distal end (2) of the catheter (10) for receiving the active agent and administering it to the body. The flexible element (16) comprises an outer tubular element (161) and an inner tubular element (167) inserted into the outer tubular element (161), with one (161) of the outer tubular element (161) and the inner tubular element (167) provided with notches (163) which enable its spinal column-like curvature towards the body site of administration.
