Pre-filled retractable needle injection ampoules

摘要

An injection device for administration of fluid medication is provided with a retraction mechanism for safety retracting the injection needle after administration of the injection. The device comprises a barrel for receiving a pre-filled medication cartridge containing a supply of fluid medication and sealed by a slidable plug. A plunger is positioned in the barrel. The plunger includes a rear portion for engaging and puncturing the plug, and for holding the plug at a stationary position as the cartridge is merged into the barrel to administer the injection. The player further includes a formal end for releasing the needle for the needle retraction mechanism when the cartridge has been urged into the barrel after the and of an injection stroke.