Tamper evident needle guard for syringes

A medicine injection device, comprising:

• a medical cartridge having a cartridge barrel and a plunger, the plunger comprising a plunger shaft slidable within the cartridge barrel;
• a body having a proximal end, a distal end, and a cavity in which the cartridge barrel is disposed;
• and
• a plunger locking mechanism attached to the proximal end of the body, the plunger locking mechanism comprising a member with an aperture slidably engaged with the plunger shaft, the aperture configured for preventing the plunger from being removed from the cartridge barrel.

A method for assembling a medicine injection device, comprising:

• inserting a medical cartridge into a cavity of a body through a proximal end of the body;
• inserting a plunger having a plunger shaft within the medical cartridge, the plunger shaft extending from the proximal end of the body;
• attaching a plunger locking mechanism to the proximal end of the body, wherein the plunger locking mechanism comprises an aperture;
• and
• slidably receiving the plunger shaft within the aperture of the plunger locking mechanism to prevent removal of the plunger from the medical cartridge.