Medical cartridge comprising a one way valve

A medical cartridge containing multiple doses of a medical drug, the medical cartridge having an outlet end being arranged to be connected to an injection needle for delivering the medical drug, wherein the medical cartridge comprises:

• a passive one way valve arranged in an interior of the medical cartridge at a position near the outlet end, the passive one way valve configured to enable a fluid flow from the interior of the medical cartridge towards the outlet end, and prevent a fluid flow from the outlet end towards the interior of the medical cartridge, the passive one way valve including a resilient valve member configured to
• be pushed into a sealing position in response to a pressure difference between a pressure prevailing between the outlet end and the passive one way valve and a pressure prevailing inside the medical cartridge being smaller than a particular threshold value, and
• be pushed away from the sealing position, thereby allowing medical drug to pass the passive one way valve, in response to the pressure difference being greater than the particular threshold value;
• and
• a filler material in the interior the medical cartridge in a region between the passive one way valve and the outlet end, said filler material configured to enable liquid to pass through the region between the passive one way valve and the outlet end, the filler material further configured to reduce a dead volume in the region between the passive one way valve and the outlet end to at least partially inhibit trapping of the medical drug in the region.