Patent ID: 10773029

Abstract:
The invention relates to a prefilled injection pen for apportioning multiple set doses of a liquid drug. The injection pen comprises a housing assembly with a removable cap rotatable coupled to the housing assembly such that the user has to rotate the removable cap upon mounting and dismounting the removable cap. Rotation of the removable cap initiates a process in which the proximal end of a needle cannula is first inserted into a cartridge permanently embedded in the housing assembly and thereafter moves the cartridge proximally to thereby pump a predetermined amount of the preservative containing liquid drug from the cartridge and into a cleaning chamber carried by an axially movable shield. The needle cannula is mounted in a needle hub which is arranged to follow rotation of the removable cap and guided helically in relation to the housing assembly such that the needle hub is moved proximally upon rotation of the removable cap. Further, the axially movable shield is operated by the needle hub to follow proximal movement of the needle hub such that the distal tip of the needle cannula is maintained inside the cleaning chamber upon axil movement of the needle hub and the needle cannula.