Tamper evident needle guard for syringes

Abstract

A medicine injection device comprises a cartridge having a cartridge barrel and a plunger having a plunger shaft slidable within the cartridge barrel. The cartridge may have, e.g., a pre-filled medicine. The medicine injection device further comprises a body having a proximal end, a distal end, and a cavity in which the cartridge barrel is disposed. The proximal end of the body may optionally form a finger grip. The medicine injection device further comprises a plunger locking mechanism attached to the proximal end of the body. The plunger locking mechanism comprises a member with an aperture slidably engaged with the plunger shaft. The locking mechanism is configured for preventing the plunger from being removed from the cartridge barrel. For example, the plunger shaft may include a locking stop, e.g., a flange, that engages with the aperture in an interference arrangement.

What is claimed is:  
     
         1 . A needle guard for syringes, comprising: 
 a medical cartridge having a cartridge barrel and a plunger, the plunger comprising a plunger shaft slidable within the medical cartridge;    a body having a proximal end, a distal end, and a cavity configured for receiving the medical cartridge; and    a plunger locking mechanism attachable to the proximal end of the body, the plunger locking mechanism comprising a member with an aperture that, when the medical cartridge is received within the cavity of the body, is configured to be slidably engaged with the plunger shaft, while preventing the plunger from being removed from the cartridge barrel.    
     
     
         2 . The needle guard of  claim 1 , wherein the medical cartridge is a syringe that comprises a needle extending from the cartridge barrel, and further comprising a shield configured to be slidably attached to the body between a retracted position for exposing the needle, and an extended position for substantially covering the needle.  
     
     
         3 . The needle guard of  claim 2 , wherein the shield is biased to slide towards the extended position.  
     
     
         4 . The needle guard of  claim 11 , wherein the plunger locking mechanism comprises a flange through which the aperture extends, the flange being mountable within the proximal end of the body.  
     
     
         5 . The needle guard of  claim 4 , wherein the proximal end of the body comprises at least one pair of opposing tab slots, and the flange comprises at least one pair of opposing tabs matable within the at least one pair of opposing tab slots.  
     
     
         6 . The needle guard of  claim 4 , wherein the aperture is formed on an edge of the flange, such that the plunger shaft can be laterally received within the aperture.  
     
     
         7 . The needle guard of  claim 1 , wherein the cartridge barrel is pre-filled with a medicine.  
     
     
         8 . 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.    
     
     
         9 . The medicine injection device of  claim 8 , wherein the medical cartridge is a syringe that comprises a needle extending from the cartridge barrel, and further comprising a shield slidably attached to the body between a retracted position for exposing the needle, and an extended position for substantially covering the needle, wherein the shield is biased to slide towards the extended position.  
     
     
         10 . The medicine injection device of  claim 9 , further comprising a frangible cap attached to the shield for preventing access to the needle.  
     
     
         11 . The medicine injection device of  claim 8 , wherein the proximal end of the body comprises a finger grip, and the plunger locking mechanism is attached to the finger grip.  
     
     
         12 . The medicine injection device of  claim 11 , wherein the finger grip comprises opposing lateral surfaces defining a recess, and the plunger locking mechanism is received in the recess.  
     
     
         13 . A needle guard for a syringe, comprising: 
 a body having a proximal end, a distal end, and a cavity being adapted to receive a medical cartridge having a cartridge barrel and a plunger, the plunger comprising a plunger shaft slidable within the medical cartridge; 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.    
     
     
         14 . The needle guard of  claim 13 , wherein the medical cartridge is a syringe that comprises a needle extending from the cartridge barrel, and further comprising a shield configured to be slidably attached to the body between a retracted position for exposing the needle, and an extended position for substantially covering the needle.  
     
     
         15 . The needle guard of  claim 13 , wherein the proximal end of the body comprises a finger grip, and the plunger locking mechanism is attachable to the finger grip.  
     
     
         16 . The needle guard of  claim 15 , wherein the finger grip comprises opposing lateral surfaces defining a recess, and the plunger locking mechanism is receivable in the recess.  
     
     
         17 . 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.    
     
     
         18 . The method of  claim 17 , wherein the medical cartridge is a syringe that comprises a needle, and further comprising attaching a shield to the body, the shield being slidable between a retracted position for exposing the needle, and an extended position for substantially covering the needle.  
     
     
         19 . The method of  claim 17 , wherein the plunger locking mechanism comprises a flange through which the aperture extends, and further comprising mounting the flange within the proximal end of the body.  
     
     
         20 . The method of  claim 19 , wherein the proximal end of the body comprises at least one pair of opposing tab slots, and the flange comprises at least one pair of opposing tabs, and further comprising mating the at least one pair of opposing tabs within the at least one pair of opposing tab slots.  
     
     
         21 . The method of  claim 17 , wherein the proximal end of the body comprises a finger grip, and further comprising attaching the plunger locking mechanism to the finger grip.  
     
     
         22 . The method of  claim 21 , wherein the finger grip comprises opposing lateral surfaces defining a recess, and further comprising receiving the plunger locking mechanism in the recess.