Single-Use Auto-Disable Syringe

A method of operating a syringe, the syringe comprising a barrel, a locking element, and a plunger rod assembly including a stopper, a user interface flange, an elongate body portion, a recess disposed along the elongate body portion, and a plurality of first teeth defining a plurality of distally facing shoulders, the locking element being positionable within the recess, the plunger rod assembly and the locking element being inserted into the barrel, the locking element being prevented from displacing proximally relative to the barrel, the method comprising:

• proximally displacing the plunger rod assembly relative to the barrel to draw fluid into the barrel, while the locking element remains substantially stationary relative to the barrel;
• engaging a proximal end of the locking element with the most distal of the distally facing shoulders, wherein the elongate body portion extends from the stopper to the flange, and the distally facing shoulders are substantially equally spaced along a majority of the elongate body portion;
• and
• distally displacing both the plunger rod assembly and the locking element to dispense the fluid from the barrel, wherein the locking element prevents re-use of the syringe.

A method of manufacturing a syringe, comprising:

• positioning a locking element within a recess of a plunger rod assembly, the plunger rod assembly including a stopper, a user interface flange, an elongate body portion extending from the stopper to the flange, and a plurality of first teeth defining a plurality of distally facing shoulders that are substantially equally spaced along a majority of the elongate body portion, the recess being disposed along the elongate body portion;
• and
• inserting the plunger rod assembly and the locking element into a syringe barrel;
• wherein the locking element is substantially prevented from displacing proximally relative to the barrel.

A method of operating a syringe, the syringe comprising a barrel, a locking element, and a plunger rod assembly including an elongate body portion, a recess disposed along the elongate body portion, a plurality of first teeth defining a plurality of distally facing shoulders, and a portion of reduced cross-sectional area configured to break upon the application of axial or torsional force to the plunger rod assembly above a predetermined limit, the plunger rod assembly and the locking element being inserted into the barrel, the locking element being prevented from displacing proximally relative to the barrel, the method comprising:

• proximally displacing the plunger rod assembly relative to the barrel to draw fluid into the barrel, while the locking element remains substantially stationary relative to the barrel;
• engaging a proximal end of the locking element with the most distal of the distally facing shoulders of the plurality of first teeth, the plurality of first teeth being disposed within the recess, the distally facing shoulders being substantially equally spaced along a majority of the elongate body portion;
• and
• distally displacing both the plunger rod assembly and the locking element to dispense the fluid from the barrel.

A method of manufacturing a syringe, comprising:

• positioning a locking element within a recess of a plunger rod assembly, the plunger rod assembly including an elongate body portion, a recess along the elongate body portion, a plurality of first teeth within the recess defining a plurality of distally facing shoulders that are substantially equally spaced along a majority of the elongate body portion, and a portion of reduced cross-sectional area configured to break upon the application of axial or torsional force to the plunger rod assembly above a predetermined limit;
• and
• inserting the plunger rod assembly and the locking element into a syringe barrel;
• wherein the locking element is substantially prevented from displacing proximally relative to the barrel.

A locking element for a syringe, for preventing reuse of the syringe, the locking element comprising:

• a generally V-shaped body portion including first and second radially extending walls joined along a longitudinal axis;
• first and second legs respectively extending in a proximal direction from the first and second walls, at least one of the legs including a proximal end portion engageable with a distally facing shoulders of a plunger rod assembly of the syringe, the proximal end portion including an outer edge having a barb portion angled radially outward for engaging an internal surface of a syringe barrel, and an end portion angled radially inward;
• and
• a distal end portion integral with the generally V-shaped body portion, the distal end portion including at least one distal edge portion extending substantially perpendicular to the longitudinal axis from the vertex of the V-shaped body portion, the distal edge portions having a length less than a distance between the vertex and an outer edge of the first leg.