Abstract: An implantable device for administering a treatment solution has a first chamber for accommodating the active solution to be administered and a second chamber for accommodating a treatment solution bolus, each chamber having a port sealed with a septum. An infusion line leading to the infusion site is connected to the outlet of the first chamber. An inlet line branches off from the infusion line and is connected to the second chamber to accommodate the active solution bolus, and includes a flow device which releases the flow path to the infusion site only when the active solution bolus is supplied at a pressure above a predetermined minimum pressure. The occurrence of life-threatening situations due to sudden administration of a large quantity of active solution is prevented if the active solution is always supplied only at a pressure below the minimum pressure at which the flow path is released.