Priming configuration for a medical device and drug delivery device comprising a priming configuration

The priming configuration comprises a piston rod (1), a bung (2), which is provided to be driven by the piston rod, and a movable element (5), which is engaged with the piston rod. The movable element is arranged to be movable in a predefined direction (10) with respect to the piston rod by a user of the drug delivery device. A movement of the movable element in the predefined direction advances the piston rod in a further direction (11), providing a priming of the drug delivery device before use. The predefined direction may especially be transverse to the further direction, and the further direction may especially be directed from the piston rod towards the bung (2). A gap (12) or clearance between the piston rod (1) and the bung (2) can thus be removed, and the stiction of the bung (2) to the cartridge (3) can be reduced.