WO2023163816A1

WO2023163816A1 - Threadless plunger rod and backstop for syringe assembly

Info

Publication number: WO2023163816A1
Application number: PCT/US2023/010745
Authority: WO
Inventors: Minhong Yu
Original assignee: Minhong Yu
Priority date: 2022-02-28
Filing date: 2023-01-13
Publication date: 2023-08-31

Abstract

A syringe assembly having a plunger rod including a plurality of plunger rod engaging mechanisms disposed along the length of the plunger rod. A backstop is configured to receive the plunger rod and includes one or more backstop engaging mechanisms positioned and configured to engage the plurality of plunger rod engaging mechanisms of the plunger rod as the plunger rod is advanced through the backstop. The plurality of plunger rod engaging mechanisms and corresponding one or more backstop engaging mechanisms are configured to permit each of the plurality of plunger rod engaging mechanisms to traverse the one or more backstop engaging mechanisms when the plunger rod is advanced through the backstop in a forward direction and to prevent the plurality of plunger rod engaging mechanisms from traversing the one or more backstop engaging mechanisms when the plunger rod is pulled back from the backstop in a rearward direction.

Description

THREADLESS PLUNGER ROD AND BACKSTOP FOR SYRINGE ASSEMBLY

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application Serial No. 63/314,559 filed February 28, 2022, entitled “Threadless Plunger Rod and Backstop for Syringe Injection System,” the contents of which is being incorporated herein by reference in its entirety.

FIELD

[0001] The present disclosure relates generally to syringe assemblies. More particularly, the present disclosure relates to syringe assemblies for preventing unwanted or accidental removal, draw back, or backward movement of the plunger rod and stopper from the barrel.

BACKGROUND

[0002] A syringe assembly as known in the art generally includes a stopper, barrel, and a needle. In operation, the syringe assembly contains a movable sealing element (stopper) that is attached to a plunger rod such that, as the plunger rod is moved forward within the barrel, the stopper acts to eject medicated liquid through the needle. Many of today’s syringes either incorporate a backstop in the distal end of the barrel or otherwise provide a backstop that is able to be secured to the distal end of the barrel. The backstop is designed to provide a finger flange for allowing a user to grasp the syringe assembly when pushing down on the thumb area of the plunger rod.

[0003] The syringe assemblies of current designs have several deficiencies including, but not limited to, the following: (1) the plunger rod often needs to be threaded at its distal end to connect to corresponding threads of the stopper in the barrel, which adds complexity in manufacturing and assembling as well as overall cost to the design; (2) the plunger rod is able to be pulled backwards with respect to the barrel; (3) the threaded plunger rod is able to be removed from the stopper by unthreading the plunger rod from the stopper either intentionally or unintentionally; (4) users can easily pull the plunger rod with attached stopper past the backstop to remove the stopper from the barrel, thus contaminating and/or spilling the medicated liquid contained in the barrel; (5) users can reuse the syringe by either drawing new medication into the syringe via the needle and pulling the plunger rod and stopper backwards or remove the stopper and fill the syringe with new injection substance before reinserting the stopper using the plunger rod; and (6) the plunger rod does not provide for metered dosing (i.e., incremental advancement of the plunger rod through barrel).

[0004] In another aspect of current syringe assemblies, the connection between the backstop and barrel of current designs typically includes the barrel flange being inserted into the backstop such that the barrel flange makes flat contact with the inner top surface of the backstop. This design also has several deficiencies including, but not limited to, the following: (1) it creates challenges during sterilization as it is difficult to ensure there is space between the barrel flange and the inner top surface of the backstop to allow for access by a sterilant to penetrate the connection; (2) during injection, the current backstops do not hold or attached onto the syringe flange to provide ergonomic structural support to the user; and (3) current backstop does not prevent users from intentionally or unintentionally remove the backstop from the syringe assembly, creating a situation where users may not have enough finger grip I leverage for proper injection and/or the removed backstop can be a contamination risk in situations when the syringe is used in a surgical environment or a choking risk when used in an environment around small children.

[0005] In another disadvantage of current backstop designs, the flange of the backstop has no anti-slip features incorporated. As such it is prone to finger slippage when the user has wet or slipper hands resulting in compromised injection and potential injury.

[0006] What is needed therefore is a syringe assembly that solves the above and other deficiencies with current syringe assemblies.

SUMMARY

[0007] The above and other needs are met by the present disclosure, which provides in one embodiment a syringe assembly including a plunger rod and a backstop. The plunger rod includes a proximal end, a distal end, and a sidewall having a length extending from the proximal end to the distal end, the sidewall including a plurality of plunger rod engaging mechanisms disposed along the length of the sidewall. The backstop includes an aperture configured to receive the plunger rod and one or more backstop engaging mechanisms positioned and configured to engage the plurality of plunger rod engaging mechanisms of the plunger rod as the sidewall of the plunger rod is advanced through the aperture of the backstop. The plurality of plunger rod engaging mechanisms and corresponding one or more backstop engaging mechanisms are configured to permit each of the plurality of plunger rod engaging mechanisms to traverse the one or more backstop engaging mechanisms when the plunger rod is advanced through the backstop in a forward direction and to prevent each of the plurality of plunger rod engaging mechanisms from traversing the one or more backstop engaging mechanisms when the plunger rod is pulled back from the backstop in a rearward direction.

[0008] According to certain embodiments, the plurality of plunger rod engaging mechanisms are positioned in a plurality of levels along the length of the sidewall of the plunger rod to provide for metered advancing of the plunger rod through one or more backstop engaging mechanisms.

[0009] According to certain embodiments, the plurality of plunger rod engaging mechanisms includes a plurality of deflectable tabs, each of the deflectable tabs including an angled ramp surface leading to a locking edge. In some embodiments, the one or more backstop engaging mechanisms includes a ring extending inward with respect to the aperture. In some embodiments, the ring includes an angled ramp surface leading to a locking edge with the angled ramp surface of the ring being positioned and configured to traverse the angled ramp surface of the plurality of deflectable tabs to assist in traversal of the plunger rod engaging mechanisms past the one or more backstop engaging mechanism when the plunger rod is advanced through the backstop in the forward direction, and the locking edge of the ring being positioned and configured to engage the locking edge of the plurality of deflectable tabs to prevent each of the plurality of plunger rod engaging mechanisms from traversing the one or more backstop engaging mechanisms when the plunger rod is pulled back from the backstop in the rearward direction.

[0010] According to certain embodiments, the plurality of deflectable tabs are arranged in a plurality of columns along the length of the sidewall of the plunger rod in a staggered pattern such that the plurality of deflectable tabs of a first column are disposed on a different level along the length of the sidewall of the plunger rod with respect to the plurality of deflectable tabs in a second column that is adjacent to the first column. [0011] According to certain embodiments, the plurality of plunger rod engaging mechanisms includes a plurality of ribs extending out from the sidewall with grooves disposed between adjacent ribs. In some embodiments, each of the plurality of ribs included an angled lower ramp surface leading to a locking edge with one of the grooves disposed above the locking edge. In some embodiments, the one or more backstop engaging mechanisms includes a plurality of deflectable tabs. Each of the plurality of deflectable tabs may include an angled ramp surface leading to a locking edge.

[0012] According to certain embodiments, the one or more backstop engaging mechanisms include a first upper backstop engaging mechanism and a second lower backstop engaging mechanism, the plurality of plunger engaging mechanisms includes at least a first plunger engaging mechanism and a second plunger engaging mechanism, and as the plunger is advanced into the backstop, the first upper backstop engaging mechanism engages the first plunger engaging mechanism and the second lower backstop engaging mechanism engages the second plunger engaging mechanism.

[0013] According to certain embodiments, the backstop includes a folded sheet having an upper surface including a first opening dimensioned and configured to receive the plunger rod and a lower surface including a second opening dimensioned and configured to receive the plunger rod. At least one of the first opening and the second opening is dimensioned and configured to operate as one of the one or more backstop engaging mechanisms, and at least one of the upper surface and the lower surface is angled with respect to the plunger rod.

[0014] According to certain embodiments, at least one of the upper and lower surface of the folded sheet is operable to deflect as the plunger is advanced through the backstop and configured to resist deflection when the plunger is pulled backwards.

[0015] According to certain embodiments, the plunger includes a hollow chamber along at least a portion of its length and at least one of a shelf-life extender and medicinal product supporting material disposed within the hollow chamber.

[0016] According to certain embodiments, the backstop includes a finger flange having anti-slip features disposed on finger contacting portion of the finger flange. [0017] According to another embodiment of the disclosure, a backstop for a syringe assembly includes one or more locking tabs extending from an entrance surface disposed adjacent an entrance of the backstop in which a syringe barrel flange is inserted into the backstop, the one or more locking tabs including a ramp surface leading to a locking edge, the angled surface for facilitating insertion of the syringe barrel flange into the backstop and the locking edge for impeding the syringe barrel flange from being removed from the backstop.

[0018] According to certain embodiments, the backstop includes a curved surface extending below the aperture and positioned and configured for creating minimal contact with a syringe barrel flange that is inserted into the backstop.

[0019] According to certain embodiments, the backstop includes one or more locking tabs extending from an entrance surface disposed adjacent an entrance of the backstop in which a syringe barrel flange is inserted into the backstop, the one or more locking tabs including a ramp surface leading to a locking edge, the angled surface for facilitating insertion of the syringe barrel into the backstop and the locking edge for impeding the syringe barrel from being removed from the backstop. In some embodiments, the one or more locking tabs are operable to be deflected for further facilitating insertion of the syringe barrel into the backstop. In some embodiments, the backstop further includes a finger flange having antislip features disposed on finger contacting portion of the finger flange.

[0020] According to yet another embodiment of the disclosure, a backstop for a syringe assembly includes an aperture for receiving a plunger rod and a curved surface extending below the aperture that is positioned and configured for creating minimal contact with a syringe barrel that is inserted into the backstop.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further advantages of the invention are apparent by reference to the detailed description when considered in conjunction with the figures, which may not be to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein: [0022] FIG. 1 is a perspective view of a syringe assembly having a plunger rod and backstop according to one embodiment of the disclosure.

[0023] FIG. 2 is a cross-sectional view of the syringe assembly of FIG. 1.

[0024] FIG. 3 are front elevational views of the plunger rod of FIG. 1 depicting the staggered arrangement of the plunger engaging mechanisms.

[0025] FIG. 4 is a front elevational view of a plunger rod according to another embodiment of the disclosure.

[0026] FIG. 5 is an overhead perspective view of a backstop according to another embodiment of the disclosure that is configured to receive the plunger rod of FIG. 4.

[0027] FIG. 6 is a cross-sectional view of the plunger rod of FIG. 4 engaging the backstop of FIG. 5.

[0028] FIG. 7 is a perspective view of a syringe assembly having a plunger rod and backstop according to another embodiment of the disclosure.

[0029] FIG. 8 is an overhead perspective view of the backstop in the syringe assembly of FIG. 7.

[0030] FIGS. 9-10 are side perspective views of backstops according to other embodiments of the disclosure.

[0031] FIG. 11 is a front perspective view of a syringe assembly with the backstop of FIG. 10.

[0032] FIG. 12 is an overhead perspective view of a plunger rod with a hollow chamber according to another embodiment of the disclosure.

[0033] FIG. 13 is a cross-sectional view of the plunger rod of FIG. 12.

[0034] FIG. 14 is a side perspective view of a backstop according to another embodiment of the disclosure.

[0035] FIG. 15 is a bottom perspective view of a backstop according to another embodiment of the disclosure.

[0036] FIG. 16 is a cross-sectional view of the backstop of FIG. 15. [0037] FIG. 17 is a front perspective view of a backstop according to another embodiment of the disclosure.

[0038] FIGS. 18 - 19 are cross-sectional views of the backstop of FIG. 17.

DETAILED DESCRIPTION

[0039] Referring to FIGS. 1 - 3, a plunger rod 20 and corresponding backstop 50 according to one embodiment of a syringe assembly 10 of the present disclosure is depicted. The plunger rod 20 includes a proximal end 22, a distal end 24, and a circumferential sidewall 26 having a length extending from the proximal end 22 to the distal end 24. A plunger rod flange 21 preferably extends radially outward from the sidewall 26 adjacent the proximal end 22. A non-threaded extension 23 preferably extends from the distal end 24 for inserting into the rear of a stopper that is inserted in the barrel (not shown). Alternately, the plunger rod 20 could include a blunt or flat end instead of the extension 23 such that the end pushes against the rear end of the stopper. The plunger rod 20 further includes a plurality of plunger rod engaging mechanisms 30 disposed along the length of the sidewall 26. As shown, the plunger rod engaging mechanisms 30 are preferably arranged in a plurality of rows/levels along the length of the sidewall 26.

[0040] The backstop 50 includes an aperture 52 through which the distal end 24 of the plunger rod 20 is operatively inserted. The backstop 50 includes a backstop engaging mechanism 60 that is operable to engage the plunger rod engaging mechanisms 30 as the plunger rod 20 is advanced past the backstop engaging mechanism 60. As shown in this embodiment the backstop engaging mechanism 60 is incorporated into the entrance of the aperture 52. However, the backstop engaging mechanism could be placed anywhere along the backstop 50 so long as it is positioned to engage with the plunger rod engaging mechanisms 30 of the plunger rod 20 as the plunger rod 20 is advanced through the aperture 52 of the backstop 50.

[0041] As further described herein, the plunger rod engaging mechanisms 30 and backstop engaging mechanism 60 are configured such that the plunger rod engaging mechanisms 30 are only able to traverse the backstop engaging mechanism 60 in the forward direction (i.e., the plunger rod 20 being advanced through the barrel of the syringe assembly). Thus, once a particular row/level (hereinafter referred to as a “level”) of the plunger rod engaging mechanisms 30 traverses the backstop engaging mechanism 60, the backstop engaging mechanism 60 prevents the plunger rod 20 from being withdrawn in a rearward direction from the backstop 50 past the level of the plunger rod engaging mechanisms 30 that already traversed the backstop engaging mechanism 60.

[0042] With continued reference to FIGS. 1 - 3, and with particular reference to the cross- sectional view of FIG. 2, the backstop engaging mechanism 60 is in the form of a ring that extends around or otherwise forms the aperture 52. The plunger rod engaging mechanisms

30 of this embodiment include deflectable latch mechanisms each disposed within recesses

31 formed in the sidewall 26 of the plunger rod 20. Each latch mechanism 30 includes a latch body 32 that extends to a locking tab 34 that extends radially out from the latch body 32. In operation, as one level of the deflectable latch mechanisms 30 is advanced past the backstop engaging mechanism 60, the backstop engaging mechanism 60 deflects the latch body 32 inward with respect to the recess 31 until the locking tab 34 is advanced past the backstop engaging mechanism 60. Once the locking tab 34 is advanced past the backstop engaging mechanism 60, the latch body 32 returns to its undeflected state such that the locking tab 34 is unable to be pulled back past the backstop engaging mechanism 60.

[0043] As shown best in FIG. 2, each locking tab 34 preferably includes a ramp 36 that is angled outward beginning at the end of the latch body 32 to assist the locking tab 34 in traversing the backstop engaging mechanism 60. The angled ramp 36 then ends at a locking edge 38 that extends substantially perpendicular to the sidewall 26. Similarly, the backstop engaging mechanism 60 may include an angled ramp 62 leading to a locking edge 64. In operation, when the plunger rod 20 is advanced downward with respect to the backstop 50 such that at least one of the plunger rod engaging mechanisms 30 traverses the backstop engaging mechanism 60, the angled ramp 36 of the plunger rod engaging mechanism 30 traverses the angled ramp 62 of the backstop engaging mechanism 60 until the locking edge 38 traverses the locking edge 64. Once locking edge 38 traverses the locking edge 64, the locking edges prevent the plunger rod 20 from being able to be pulled back past the particular locking edge 38 of the plunger rod engaging mechanism 30.

[0044] To assist the traversal of the locking edges 38 and 64, the latch body 32 and locking tab 34 of the plunger rod engaging mechanism 30 is able to be deflected (e.g., into recess 31 of the sidewall 26 of the plunger rod 20 as described above). However, in other embodiments, the deflection could just be the locking tab 34 being able to be deflected inward with the sidewall 26 based on the general ability of the sidewall 26 able to be deflected. In addition, or alternatively, the backstop engaging mechanism 60 may be dimensioned and configured such that it is able to be deflected outward to assist in the traversal of a plunger rod engaging mechanism 30 past the backstop engaging mechanism 60.

[0045] According to certain embodiments, and as depicted in FIG. 3, the plurality of plunger rod engaging mechanisms 30 are spaced apart from each other on each level along a plurality of “columns” of the sidewall 26. Further, each level of the plunger rod engaging mechanisms 30 of a particular column may be slightly offset or staggered from the plunger rod engaging mechanisms 30 of an adjacent column. Thus, the plunger rod 20 of FIG. 3 includes many different levels of plunger rod engaging mechanisms 30. As should be understood, the more offsetting levels of plunger rod engaging mechanisms 30 provided along the length of the sidewall 26 of the plunger rod 20, the smaller the movements of the plunger rod 20 needed to have one of the plunger rod engaging mechanisms 30 traverse the backstop engaging mechanism 60. This allows for more incremental and/or metered movements of the plunger rod 20 with respect to the barrel, and thus metered dosing of the medicated fluid within the barrel to the patient. In other words, by staggering the plunger rod engaging mechanisms 30 along the length of the plunger rod 20, the vertical distance between adjacent plunger rod mechanisms 30 is minimized resulting in consistent locking of the plunger rod 20 position with respect to the backstop 50 as the plunger rod 20 is depressed. As should also be understood, plunger rod engaging mechanisms 30 of different columns may also be positioned on the same level to help withstand even more force when someone tries to pull the plunger rod 20 backwards from the backstop 50.

[0046] With reference to FIGS. 4 - 6, and according to another embodiment of the disclosure, plunger rod 120 of syringe assembly 100 includes a sidewall that includes a plurality of ribs 130 extending out from the sidewall to form grooves 132 between the ribs 130. Backstop 150 similarly includes an aperture 152 through which the plunger rod 120 is inserted to connect the plunger rod 120 to the syringe assembly 100 and push the plunger rod 120 through the barrel (not shown). According to this embodiment, the backstop 150 includes one or more backstop engaging mechanisms 160 in the form of deflectable tabs. In operation, when the plunger rod 120 is pushed downward through the aperture 152 of the backstop 150, the ribs 130 of the plunger rod 120 are dimensioned and configured to deflect the tabs 160 of the backstop 150 outward. Once a rib 130 of a particular level traverses the tabs 160, the tabs 160 move back to the undeflected position such that the tabs 160 fit within the groove 132 above the rib 130 that just traversed the tab 160 such as shown in FIG. 6.

[0047] Similar to the plunger rod engaging mechanisms 30 described above with respect to the embodiment described in FIGS. 1 - 3, the ribs 130 as shown best in the cross- sectional view of FIG. 6 preferably include an angled lower surface 136 leading to a locking edge upper surface 138 for facilitating traversal of the ribs 130 past the tabs 160 of the backstop 150. Referring to FIG. 5, the tabs 160 preferably also include an angled upper surface 162 leading to a locking edge lower surface 164. Thus, the angled lower surfaces 136 and 162 facilitate traversal of the ribs 130 past the tabs 160 while the locking edges 138 and 164 prevent the ribs 130 from being withdrawn from the backstop once a rib 130 passes the tabs 160.

[0048] According to another aspect of the present disclosure, and with reference to FIGS. 7 - 8, a syringe assembly 200 includes a plunger rod 220 and a backstop 250 substantially as described above with respect to the embodiment of FIGS. 4 - 6. However, according to this embodiment, the plunger rod 220 further includes support ribs 222 extending along at least a portion of the length of the plunger rod 220. The embodiment of FIG. 7 includes three support ribs 222 and the backstop 250 includes four backstop engaging mechanisms 260. While the numbers could vary, it is preferred that if the number of ribs 222 is odd, the number of backstop engaging mechanisms 260 is even to ensure that the ribs 222 will not align with the backstop engaging mechanisms 260. This ensures that at least one plunger rod engaging mechanism 230 (which are separated by the ribs 222) on a particular level will always engage with one of the backstop engaging mechanisms 260. In preferred embodiments, the number of ribs 222 is always one less than the number of backstop engaging mechanisms 260. In other embodiments, the number of support ribs 222 is always less than or greater than the number of backstop engaging mechanisms 260. [0049] According to other embodiments of the disclosure, and with reference to FIGS. 9 - 11, backstops 350 may include a first backstop engaging mechanism 360a in the form of a fist slot or aperture and/or a second backstop engaging mechanism 360b in the form of a second slot or aperture. As a plunger rod 320 in a syringe assembly 300 such as depicted in FIG. 11 is inserted into the backstop 350, the first backstop engaging mechanism 360a engages a first plunger rod engaging mechanism 330a and the second backstop engaging mechanism 360b engages a second plunger rod engaging mechanism 330b. In preferred embodiments, one or both of the first backstop engaging mechanism 360a and second backstop engaging mechanism 360b are operable to deflect as the backstop engaging mechanism traverses the corresponding plunger rod engaging mechanism. In certain embodiments, the slot of the first backstop engaging mechanism 360a may include a larger circumference than the second backstop engaging mechanism 360b. In other embodiments, the first and second backstop engaging mechanism 360a and 360b are substantially the same size. In other embodiments, and with particular reference to FIG. 9, only first backstop engaging mechanism 360a engages the plunger rod engaging mechanisms (330a and 330b) while the second backstop engaging mechanism 360b serves primarily as a support structure or anchor for the first backstop engaging mechanism 360a so that only the first backstop engaging mechanism 360a deflects as the plunger rod 320 is pushed or moved forward.

[0050] In certain embodiments, the first backstop engaging mechanism 360a and second backstop engaging mechanism 360b of this embodiment may be formed by a piece of folded sheet metal such that the first backstop engaging mechanism 360a is configured to deflect downward when traversing the first plunger rod engaging mechanism 330a to assist in the traversal and configured to resist deflection in the opposite (i.e., upward direction) to prevent the first stop backstop engaging mechanism 360a from being pulled back past the first plunger rod engaging mechanism 330a. Similarly, the folded sheet could be formed of plastic or other materials that are able to be similarly configured to be deflected downward as the first backstop engaging mechanism 360a is traversing the first plunger rod engaging mechanism 330a and to resist deflection in the upward direction. In certain embodiments, the folded sheet with first and second backstop engaging mechanisms 360a and 360b is integrated into a backstop for the syringe assembly that also includes the finger flange. In other embodiments, the folded sheet may be integrated into a backstop that is disposed within the barrel of the syringe assembly.

[0051] For purposes of the present disclosure, it should be understood that the plunger rod engaging mechanisms and corresponding backstop engaging mechanism(s) can have various geometries within the scope of the present disclosure so long as the mechanisms permit the plunger rod to be advanced incrementally through the backstop while preventing rearward movement of the plunger rod from the backstop once a particular level of plunger rod engaging mechanisms traverse one or more backstop engaging mechanisms. As described above, the plunger rod engaging mechanisms and/or backstop engaging mechanism(s) preferably include an angled surface to further facilitate the traversal. Further, the plunger rod engaging mechanisms and/or backstop engaging mechanisms may be configured to deflect inward, outward, upward, and/or downward while the plunger rod engaging mechanism moves past the backstop engaging mechanism to further facilitate traversal and then configured to return to its undeflected position following traversal to prevent rearward movement of the plunger rod within the barrel of the syringe assembly.

[0052] According to certain embodiments, the plunger rod includes a hollow interior. For example, when the plunger rod engaging mechanisms described above are intended to deflect inward (e.g., the embodiment of FIGS. 1 - 3), the plunger rod is preferably hollow. According to other embodiments, the plunger rod may include a solid interior. Further, while the plunger rods shown herein include a circumferential sidewall such that the plunger rod is cylindrical, it should be understood that other shapes such as square, octagonal, or triangular of the plunger rod (and corresponding backstop recess) are possible and within the scope of the present disclosure.

[0053] According to certain embodiments, the backstops described herein may be directly incorporated into the barrel of the syringe assemblies. This can be accomplished in various ways such as being inj ection molded together with the barrel. Other types of manufacturing methods as known in the art may also be used to provide an integrated barrel and backstop such as described herein where the plunger rod is prevented from being pulled backward from the backstop. Further, as noted above, the backstop engaging mechanisms may be located anywhere along the recess of the backstop such as adjacent the entrance, within the body, or adjacent the exit of the backstop.

[0054] According to another aspect of the disclosure, and with reference to FIGS. 12 - 13, the plunger rod 420 includes a hollow chamber 421 that is accessible at the proximal end 422 of the plunger rod 420. The chamber 421 may be used to place desiccants, oxygen absorbers, or any other materials known to aid in a product’s shelf life or other product supporting uses. The hollow chamber can be sealed off by any sealing element 424 such as a Tyvek® seal, aluminum seal, elastomeric plug or any other sealing methods known in the art. The sealing material may be porous, semi-porous, or non-porous.

[0055] According to another aspect of the disclosure, and with reference to FIG. 14, the backstop 550 includes one or more locking tabs 570 extending from an entrance surface 582 disposed adjacent the entrance 580 of the backstop 550. According to this embodiment, the barrel flange (not shown) is intended to be inserted into the entrance 580 of the backstop 550 for connecting the barrel (not shown) to the backstop 550. As depicted, the locking tabs 570 include an angled surface 572 that is angled toward the entrance 580 for facilitating the barrel to traverse the locking tabs 570. The angled surface 572 leads to a locking edge 574 for preventing or otherwise impeding the barrel from being removed from the backstop 550 once the barrel flange traverses the locking tabs 570. In certain embodiments, the entrance surface 582 from which the locking tabs 570 extend may also be configured to deflect to help facilitate the traversal of the barrel pass the locking tabs 570.

[0056] According to another aspect of the disclosure, and with reference to FIGS. 15 - 16, the backstop 650 includes a finger flange 654. On the bottom surface of the finger flange 654, the surface includes anti-slip features 656 such as knurlments, bumps, bars, etc. where the user’s fingers would typically contact the backstop 650. As shown, the backstop 650 may also include one or more extensions 658 extending downward from the inner top surface of the backstop 650. During injection, the force from the user’s fingers against the backstop finger contacting area (i.e., area that includes the anti-slip features 656) and/or the force from the user’s thumb pressing down on the plunger rod result in the barrel flange being pressed up against the extensions 658, which creates a vice like grip and also provides additional support structure to the backstop 650. The space created by the extensions 658 also allows for more room for sterilant to penetrate during sterilization.

[0057] According to another aspect of the disclosure, and with reference to FIGS. 17 - 19, the backstop 750 may include a curved surface 790 extending below the aperture 752 and/or along the interior space of the backstop 750. The curved surface 790 is intended to create minimal contact with the barrel flange that is inserted into the backstop 750. The curved surface provides for easier sterilization by allowing easier access while minimizes dead space or otherwise hard to access spaces for sterilant such as ethylene dioxide or vaporized hydrogen peroxides during sterilization.

[0058] The foregoing description of preferred embodiments for this disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the disclosure and its practical application, and to thereby enable one of ordinary skill in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

CLAIMS What is claimed is:

1. A syringe assembly comprising: a plunger rod having a proximal end, a distal end, and a sidewall having a length extending from the proximal end to the distal end, the sidewall including a plurality of plunger rod engaging mechanisms disposed along the length of the sidewall; and a backstop having an aperture configured to receive the plunger rod and one or more backstop engaging mechanisms positioned and configured to engage the plurality of plunger rod engaging mechanisms of the plunger rod as the sidewall of the plunger rod is advanced through the aperture of the backstop, wherein the plurality of plunger rod engaging mechanisms and corresponding one or more backstop engaging mechanisms are configured to permit each of the plurality of plunger rod engaging mechanisms to traverse the one or more backstop engaging mechanisms when the plunger rod is advanced through the backstop in a forward direction and to prevent each of the plurality of plunger rod engaging mechanisms from traversing the one or more backstop engaging mechanisms when the plunger rod is pulled back from the backstop in a rearward direction.

2. The syringe assembly of Claim 1 wherein the plurality of plunger rod engaging mechanisms are positioned in a plurality of levels along the length of the sidewall of the plunger rod to provide for metered advancing of the plunger rod through one or more backstop engaging mechanisms.

3. The syringe assembly of Claim 1 wherein the plurality of plunger rod engaging mechanisms includes a plurality of deflectable tabs, each of the deflectable tabs including an angled ramp surface leading to a locking edge.

4. The syringe assembly of Claim 3 wherein the one or more backstop engaging mechanisms includes a ring extending inward with respect to the aperture.

5. The syringe assembly of Claim 4 wherein: the ring includes an angled ramp surface leading to a locking edge, the angled ramp surface of the ring is positioned and configured to traverse the angled ramp surface of the plurality of deflectable tabs to assist in traversal of the plunger rod engaging mechanisms past the one or more backstop engaging mechanism when the plunger rod is advanced through the backstop in the forward direction, and the locking edge of the ring is positioned and configured to engage the locking edge of the plurality of deflectable tabs to prevent each of the plurality of plunger rod engaging mechanisms from traversing the one or more backstop engaging mechanisms when the plunger rod is pulled back from the backstop in the rearward direction.

6. The syringe assembly of Claim 3 wherein the plurality of deflectable tabs are arranged in a plurality of columns along the length of the sidewall of the plunger rod in a staggered pattern such that the plurality of deflectable tabs of a first column are disposed on a different level along the length of the sidewall of the plunger rod with respect to the plurality of deflectable tabs in a second column that is adjacent to the first column.

7. The syringe assembly of Claim 1 wherein the plurality of plunger rod engaging mechanisms includes a plurality of ribs extending out from the sidewall with grooves disposed between adjacent ribs.

8. The syringe assembly of Claim 7 wherein each of the plurality of ribs included an angled lower ramp surface leading to a locking edge with one of the grooves disposed above the locking edge.

9. The syringe assembly of Claim 8 wherein the one or more backstop engaging mechanisms includes a plurality of deflectable tabs.

10. The syringe assembly of 9 wherein each of the plurality of deflectable tabs includes an angled ramp surface leading to a locking edge.

11. The syringe assembly of Claim 1 wherein: the one or more backstop engaging mechanisms include a first upper backstop engaging mechanism and a second lower backstop engaging mechanism, the plurality of plunger engaging mechanisms includes at least a first plunger engaging mechanism and a second plunger engaging mechanism, and as the plunger is advanced into the backstop, the first upper backstop engaging mechanism engages the first plunger engaging mechanism and the second lower backstop engaging mechanism engages the second plunger engaging mechanism.

12. The syringe assembly of Claim 1 wherein the backstop includes a folded sheet having an upper surface including a first opening dimensioned and configured to receive the plunger rod and a lower surface including a second opening dimensioned and configured to receive the plunger rod, and wherein at least one of the first opening and the second opening is dimensioned and configured to operate as one of the one or more backstop engaging mechanisms, and wherein at least one of the upper surface and the lower surface is angled with respect to the plunger rod.

13. The syringe assembly of Claim 12 wherein at least one of the upper and lower surface of the folded sheet is operable to deflect as the plunger is advanced through the backstop and configured to resist deflection when the plunger is pulled backwards.

14. The syringe assembly of Claim 1 wherein the plunger includes a hollow chamber along at least a portion of its length and at least one of a shelf-life extender and medicinal product supporting material disposed within the hollow chamber.

15. The syringe assembly of Claim 1 wherein the backstop includes a finger flange having anti-slip features disposed on finger contacting portion of the finger flange.

16. The syringe assembly of Claim 1 wherein the backstop includes one or more locking tabs extending from an entrance surface disposed adjacent an entrance of the backstop in which a syringe barrel flange is inserted into the backstop, the one or more locking tabs including a ramp surface leading to a locking edge, the angled surface for facilitating insertion of the syringe barrel flange into the backstop and the locking edge for impeding the syringe barrel flange from being removed from the backstop.

17. The syringe assembly of Claim 1 wherein the backstop includes a curved surface extending below the aperture and positioned and configured for creating minimal contact with a syringe barrel flange that is inserted into the backstop.

18. A backstop for a syringe assembly, the backstop including one or more locking tabs extending from an entrance surface disposed adjacent an entrance of the backstop in which a syringe barrel flange is inserted into the backstop, the one or more locking tabs including a ramp surface leading to a locking edge, the angled surface for facilitating insertion of the syringe barrel into the backstop and the locking edge for impeding the syringe barrel from being removed from the backstop.

19. The backstop of Claim 18 wherein the one or more locking tabs are operable to be deflected for further facilitating insertion of the syringe barrel into the backstop.

20. The backstop of Claim 18 further comprising a finger flange having antislip features disposed on finger contacting portion of the finger flange.

21. A backstop for a syringe assembly, the backstop having an aperture for receiving a plunger rod and including a curved surface extending below the aperture that is positioned and configured for creating minimal contact with a syringe barrel that is inserted into the backstop.