Filter system for use in medical devices

A device for administering a liquid medical formulation which is held in a container (3) inserted in the device and is expelled from the device through at least one nozzle opening (12e), wherein, before flowing through the at least one nozzle opening (12e), the liquid medical formulation flows through a very fine filter (120 which is formed by a microstructured component (12), and wherein a pre-filter (27) is arranged in front of the microstructured component (12) inside the device, in the flow path of the liquid, characterised in that a fine filter (28) is additionally provided between the pre-filter (27) and the microstructured component (12) in the flow path of the liquid, the fine filter (28) being different from the pre-filter (27), so that the particles of different sizes or natures are deposited on the pre-filter (27) and fine filter (28) before the formulation enters the microstructured component and an adsorption filter (32) is arranged in the flow path between pre-filter (27) and very fine filter (120, the adsorption filter (32) being different from the pre-filter (27), so that particles of different sizes or natures are deposited on the pre-filter (27) and adsorption filter (32) before the formulation enters the microstructured component (12), the mode of action of the adsorption filter being characterised in that particles from a liquid flowing through the filter are able to accumulate on the surface of the filter as a result of intermolecular interactions.