Device for locking a plunger rod of a syringe after use and preventing re-use of the syringe, and syringe assembly

A syringe assembly comprising:

• a syringe barrel pre-filled with a selected dose of medication and having a distal end, an open proximal end opposite to the distal end, a sidewall extending between the distal end and the open proximal end defining a chamber, and a flange provided adjacent said open proximal end, the flange being relatively slim in a direction transverse to a longitudinal direction of the barrel;
• a plunger disposed within the chamber of the syringe barrel;
• a plunger rod associated with the plunger and connected with the plunger, a proximal end of the plunger rod being formed disc-shaped;
• and
• a locking device, which is mounted to the flange adjacent said proximal end by positive-fit, for locking the plunger rod at or near a foremost axial position of the distal end of the plunger rod in the barrel after use of the syringe and preventing re-use of the syringe;
• wherein
• said locking device comprises
• a mounting portion clipped onto the flange adjacent said open proximal end of the syringe barrel by positive-fit by pushing the mounting portion onto the flange along the direction transverse to the longitudinal direction of the syringe barrel, and
• a plunger rod locking portion for locking the axial position of the plunger rod after use of the syringe, wherein
• an outer width of the mounting portion is larger than an outer width of the flange so that the mounting portion is configured to serve as a finger rest during use of the syringe,
• a communication channel is formed in the locking device for enabling insertion of the plunger rod into the open proximal end of the barrel via the plunger rod locking portion and the mounting portion;
• wherein
• a width of the communication channel is larger inside the plunger rod locking portion to form a chamber for receiving the disc-shaped proximal end of the plunger rod after use of the syringe, and
• the plunger rod locking portion comprises a plurality of positive locking devices configured to positively lock the axial position of the plunger rod by positive-fit engagement with the disc-shaped proximal end of the plunger rod, for locking the plunger rod at or near a foremost axial position of a distal end of the plunger rod in the syringe barrel after use of the syringe;
• wherein
• the chamber formed by the plunger rod locking portion is configured for preventing full access to the disc-shaped proximal end of the plunger rod from outside the plunger rod locking portion, to prevent withdrawal of the disc-shaped proximal end of the plunger rod out of the chamber, when the axial position of the plunger rod is positively locked,
• the plunger rod locking portion is formed as a cage-like cylindrical member formed by two annular webs interconnected by a plurality of axial connecting webs, wherein each positive locking device of the plurality of positive locking devices is provided on an inner side of an annular web or of an axial connecting web, and
• a width of the communication channel is reduced at least in sections to a width that is smaller than an outer diameter of a plunger used for sealing the barrel, for preventing inadvertent removal of the plunger from the barrel via the communication channel.

A locking device for locking a plunger rod of a syringe after use and preventing re-use of the syringe, wherein

• the syringe includes a barrel having an open proximal end and a flange provided adjacent said open proximal end, wherein the barrel is configured to receive the plunger rod through said open proximal end and a proximal end of the plunger rod is formed disc-shaped,
• said locking device comprising
• a mounting portion configured for mounting the locking device to the flange adjacent said open proximal end of the barrel by positive-fit by pushing the mounting portion onto the flange along the direction transverse to the longitudinal direction of the barrel and clipping the mounting portion onto the flange, and
• a plunger rod locking portion for locking an axial position of the plunger rod after use of the syringe, wherein
• a communication channel is formed in the locking device for enabling insertion of the plunger rod into the open proximal end of the barrel via the plunger rod locking portion and the mounting portion;
• wherein
• a width of the communication channel is larger inside the plunger rod locking portion to form a chamber for receiving the disc-shaped proximal end of the plunger rod after use of the syringe,
• the plunger rod locking portion comprises a plurality of positive locking devices configured to positively lock the axial position of the plunger rod by positive-fit engagement with the disc-shaped proximal end of the plunger rod, for locking the plunger rod at or near a foremost axial position of a distal end of the plunger rod in the barrel after use of the syringe, and
• the plunger rod locking portion is formed as a cage-like cylindrical member formed by two annular webs interconnected by a plurality of axial connecting webs, wherein each positive locking device of the plurality of positive locking devices is provided on an inner side of an annular web or of an axial connecting web.