Plunger rod and syringe including same

Abstract

The plunger rod is for use with a syringe having a syringe barrel. The plunger includes an elongate body having a proximal end, a distal end opposite the proximal end, a central axis extending between the proximal and distal ends, a first curved end surface, a second curved end surface, and a junction portion connecting the first and second curved end surfaces. The first curved end surface, the second curved end surface, and the junction portion each extend between the proximal and distal ends. The first and second curved end surfaces are both configured in a circle defined by the periphery of the elongate body.

Description

[Technical Field]

[0001] Background of the Invention Field of Disclosure The disclosed concepts generally relate to a plunger rod for use in a syringe barrel that may be associated with an automatic injector. The disclosed concepts further relate to an injector, such as a manual injector, that includes a plunger rod assembly. [Background technology]

[0002] 2. Description of Related Art Syringes, particularly manually operated hypodermic syringes, are well known in the medical field for dispensing fluids such as medications or for withdrawing biological fluid samples therefrom. A conventional syringe assembly typically includes a syringe barrel having a fluid opening at one end and a plunger assembly slidably disposed through the syringe barrel and disposed at the opposite end. The plunger assembly typically includes a rigid plunger rod having a linear longitudinal axis extending through the barrel, with a plunger head or stopper disposed at the distal end of the plunger rod and a thumb press provided at the proximal end of the plunger rod. In use, the plunger rod can be retracted through the syringe barrel to aspirate or fill the syringe barrel with a fluid such as a medication. The plunger rod can also be advanced through the syringe barrel to expel a fluid such as a medication from within the syringe barrel. To deliver medication to a patient, the opening of the syringe barrel may be adapted for fluid communication with the patient, such as via a hypodermic needle attached to the distal end of the syringe barrel or via a standard Luer fitting extending from the distal end of the syringe barrel for attachment to a fluid line. Operation of a plunger rod assembly within a syringe barrel is well known in the medical field. Summary of the Invention [Problem to be solved by the invention]

[0003] In a typical medical setting, many syringes are used each year. As a result, it is desirable for syringe plunger rods to be manufactured as cost-effectively as possible, to be relatively strong (e.g., to withstand loads experienced during use), and to be manufactured with relatively short cycle times when molded. Accordingly, there is a need in the art for such improved plunger rods and syringes including the same. [Means for solving the problem]

[0004] overview In one embodiment, a plunger rod is provided for use with a syringe having a syringe barrel. The plunger includes an elongate body having a proximal end, a distal end opposite the proximal end, a central axis extending between the proximal and distal ends, a first curved end surface, a second curved end surface, and a junction portion joining the first curved end surface to the second curved end surface. The first curved end surface, the second curved end surface, and the junction portion each extend between the proximal and distal ends. The first curved end surface and the second curved end surface are both configured in a circle defined at least in part by the periphery of the elongate body.

[0005] In another aspect, a plunger rod is provided for use with a syringe having a syringe barrel, the plunger rod comprising an elongate body having a proximal end, a distal end opposite the proximal end, a central axis extending between the proximal and distal ends, and a junction portion extending between the proximal and distal ends, the junction portion at least partially defining an arcuate periphery of the elongate body, the junction portion not intersecting the central axis.

[0006] In another aspect, a syringe assembly includes a syringe barrel having a sidewall, a distal end, and a proximal end, and a plunger rod including an elongate body having a proximal end, a distal end opposite the proximal end of the elongate body, a central axis extending between the proximal end of the elongate body and the distal end of the elongate body, a first curved end surface, a second curved end surface, and a junction portion joining the first and second curved end surfaces, each of the first curved end surface, the second curved end surface, and the junction portion extending between the proximal end of the elongate body and the distal end of the elongate body, wherein the first and second curved end surfaces together form a circle defined by the periphery of the elongate body.

[0007] In another aspect, a syringe assembly includes a syringe barrel having a sidewall, a distal end, and a proximal end, and a plunger rod having a proximal end, a distal end opposite the proximal end of an elongate body, a central axis extending between the proximal end of the elongate body and the distal end of the elongate body, and a junction portion extending between the proximal end of the elongate body and the distal end of the elongate body, the junction portion at least partially defining an arcuate circumference of the elongate body, the junction portion not intersecting the central axis.

[0008] Various other aspects of the disclosure are described in one or more of the following clauses.

[0009] Clause 1. A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising: an elongate body having a proximal end, a distal end opposite the proximal end, and a central axis extending between the proximal end and the distal end; a first curved end surface, a second curved end surface, and a junction portion joining the first curved end surface and the second curved end surface, each of the first curved end surface, the second curved end surface, and the junction portion extending between the proximal end and the distal end, and the first curved end surface and the second curved end surface together configured in a circle defined by the outer periphery of the elongate body.

[0010] Clause 2. A plunger rod as described in Clause 1, wherein the joining portion comprises an intermediate surface, a first connecting surface extending from the intermediate surface to the first curved end surface, and a second connecting surface extending from the intermediate surface to the second curved end surface, the intermediate surface, the first curved end surface, and the second curved end surface together being configured in a circle defined by the outer periphery of the elongated body.

[0011] Clause 3. The plunger rod of clause 2, wherein the first connecting surface is a first angled surface relative to the intermediate surface, and the second connecting surface is a second angled surface relative to the intermediate surface.

[0012] Clause 4. The plunger rod of clause 3, wherein the first angled surface and the second angled surface each extend from the intermediate plane at a respective angle greater than or equal to 90 degrees relative to the intermediate plane.

[0013] Clause 5. The plunger rod of clause 1, wherein the first curved end surface, the second curved end surface, and the junction portion do not intersect with a central axis of the elongate body.

[0014] Clause 6. The plunger rod of clause 1, wherein the interface portion intersects the central axis and extends directly from the first curved end surface to the second curved end surface.

[0015] Clause 7. The plunger rod of clause 6, wherein the elongate body has a generally S-shaped transverse cross-section.

[0016] Clause 8. The plunger rod of clause 1, wherein the plunger rod further comprises a plurality of support ribs extending from the elongate body between the proximal and distal ends.

[0017] Clause 9. The plunger rod of clause 1, wherein the arcuate circumference is discontinuous.

[0018] Clause 10. A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising an elongate body having a proximal end, a distal end opposite the proximal end, a central axis extending between the proximal end and the distal end, and a junction portion extending between the proximal end and the distal end, the junction portion at least partially defining an arcuate periphery of the elongate body, and the junction portion does not intersect the central axis.

[0019] Clause 11. The plunger rod of clause 10, wherein the arcuate outer periphery is concave toward the central axis.

[0020] Clause 12. The plunger rod of clause 10, wherein the plunger rod further comprises a plurality of support ribs extending from the elongate body between the proximal and distal ends.

[0021] Clause 13. The plunger rod of clause 10, wherein the arcuate circumference is discontinuous.

[0022] Clause 14. The plunger rod of clause 10, further comprising a stopper overmolded on the elongate body.

[0023] Clause 15. A syringe assembly comprising: a syringe barrel having a sidewall, a distal end, and a proximal end; and an elongate body having a proximal end, a distal end opposite the proximal end of the elongate body, and a central axis extending between the proximal end of the elongate body and the distal end of the elongate body, a first curved end surface, a second curved end surface, and a junction portion joining the first curved end surface to the second curved end surface, wherein each of the first curved end surface, the second curved end surface, and the junction portion extends between the proximal end of the elongate body and the distal end of the elongate body, and wherein the first curved end surface and the second curved end surface together form a circle defined by the periphery of the elongate body.

[0024] Clause 16. A syringe assembly as described in Clause 15, wherein the joining portion comprises an intermediate surface, a first connecting surface extending from the intermediate surface to the first curved end surface, and a second connecting surface extending from the intermediate surface to the second curved end surface, the intermediate surface, the first curved end surface, and the second curved end surface together being configured in a circle defined by the outer periphery of the elongate body.

[0025] Clause 17. The syringe assembly of clause 16, wherein the first connecting surface is a first angled surface relative to the intermediate surface, and the second connecting surface is a second angled surface relative to the intermediate surface.

[0026] Clause 18. The syringe assembly of clause 17, wherein the first angled surface and the second angled surface each extend from the intermediate plane at an angle equal to or greater than 90 degrees relative to the intermediate plane.

[0027] Clause 19. The syringe assembly of clause 15, wherein the first curved end surface, the second curved end surface, and the joining portion do not intersect with a central axis of the elongate body.

[0028] Clause 20. The syringe assembly of clause 15, wherein the plunger rod further comprises a thumb depression disposed at a proximal end of the elongate body, the thumb depression being wider than the syringe barrel.

[0029] Clause 21. The syringe assembly of clause 15, wherein the plunger rod further comprises a coupling portion disposed at the distal end, and the syringe assembly further comprises a stopper coupled to the coupling portion and disposed internally relative to the syringe barrel.

[0030] Clause 22. The syringe assembly of clause 15, wherein the arcuate periphery is discontinuous.

[0031] Clause 23. A syringe assembly comprising: a syringe barrel having a sidewall, a distal end, and a proximal end; and a plunger rod having an elongate body having a proximal end, a distal end opposite the proximal end of the elongate body, and a central axis extending between the proximal end of the elongate body and the distal end of the elongate body, and a junction extending between the proximal end of the elongate body and the distal end of the elongate body, wherein the junction at least partially defines an arcuate periphery of the elongate body, and the junction does not intersect the central axis.

[0032] Clause 24. A syringe assembly as described in clause 23, wherein the arcuate outer periphery is concave toward the central axis.

[0033] Clause 25. The syringe assembly of clause 23, wherein the plunger rod further comprises a thumb depression disposed at a proximal end of the elongate body, the thumb depression being wider than the syringe barrel.

[0034] Clause 26. The syringe assembly of clause 23, wherein the plunger rod further comprises a coupling portion disposed at a distal end of the elongate body, and wherein the syringe further comprises a stopper coupled to the coupling portion and disposed internally relative to the syringe barrel.

[0035] Clause 27. The syringe assembly of clause 23, wherein the arcuate periphery is discontinuous.

[0036] Further details and advantages of the various embodiments described herein will become apparent from a review of the following detailed description of the various embodiments in conjunction with the accompanying drawing figures.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present disclosure, as well as the manner in which they are achieved, will become more apparent, and the disclosure itself will be better understood, by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 is a perspective view of a syringe according to one non-limiting embodiment of the disclosed concepts. [Figure 2] 2 is a cross-sectional view of the syringe of FIG. 1 taken along line AA of FIG. [Figure 3] 3 is a perspective view of a plunger rod for the syringe of FIG. 1; FIG. [Figure 4] 4 is a perspective view of another plunger rod that may be used with the syringe of FIG. 1. FIG. [Figure 5] 5 is a side view of the plunger rod of FIG. 3. FIG. [Figure 6]6 is a cross-sectional view of the plunger rod of FIG. 5 taken along line BB of FIG. 5. [Figure 7] FIG. 7 is a side view of a prior art plunger rod. [Figure 8] 8 is a cross-sectional view of the plunger rod of FIG. 7 taken along line CC of FIG. [Figure 9] FIG. 9 is a cross-sectional view of another plunger rod that may be used with the syringe of FIG. 1 in accordance with another non-limiting embodiment of the disclosed concepts. DETAILED DESCRIPTION OF THE INVENTION

[0039] Corresponding reference characters indicate corresponding parts throughout the several views. The examples set forth herein illustrate exemplary embodiments of the present disclosure, and such examples should not be construed as limiting the scope of the present disclosure in any way.

[0040] Detailed Description The following description is provided to enable one of ordinary skill in the art to make and use the described embodiments designed to carry out the concepts. However, various modifications, equivalents, variations, and alternatives will remain readily apparent to those skilled in the art. All such modifications, variations, equivalents, and alternatives are intended to be within the spirit and scope of the concepts.

[0041] For purposes of the following description, the terms "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof, shall refer to the concepts as oriented in the drawing figures. However, it is understood that the concepts may assume various alternative variations unless expressly specified to the contrary. It should also be understood that the specific devices illustrated in the accompanying drawings and described in the following specification are merely exemplary embodiments of the concepts. Accordingly, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered limiting.

[0042] In the following discussion, "distal" refers generally to the direction toward the end of the syringe assembly adapted to engage a separate device, such as a needle assembly or an IV connection assembly, and "proximal" refers to the direction opposite distal, i.e., away from the end of the syringe assembly adapted for engagement with a separate device. For purposes of this disclosure, the above references will be used in describing the components of a syringe assembly according to this disclosure.

[0043] 1 and 2 , syringe assembly 2 includes syringe barrel 4 having a distal end, a proximal end, and a sidewall defining a syringe interior therein. Syringe assembly 2 further includes a piston or stopper 6 positionable within the syringe interior of syringe barrel 4, a flange 8 extending radially outward from the proximal end of syringe barrel 4, and a plunger rod 10 insertable within the syringe interior of syringe barrel 4. In one embodiment, plunger rod 10 includes stopper 6, which may be overmolded onto elongated body 12 of plunger rod 10. Stopper 6 may be a polymeric material such as polyurethane (PU), silicone, and thermoplastic elastomer (TPE). Syringe assembly 2 may be adapted for dispensing and delivering fluids and / or collecting fluids. For example, syringe assembly 2 may be used for injecting or infusing fluids, such as medication, into a patient. Syringe assembly 2 may also be adapted for aspirating fluid into syringe barrel 4, such as withdrawing medication into the syringe interior and / or withdrawing a fluid sample therein. Syringe assembly 2 is intended for use in connection with a patient's needle by connecting syringe assembly 2 to a separate needle assembly (not shown), or alternatively for connection to an intravenous (IV) connection assembly (not shown). It may be understood that the present disclosure may be used with any type of syringe, including those located in controlled storage environments where storage space is limited. These types of syringes include traditional prefilled syringe assemblies, metered dose syringes, aspirating syringes for withdrawing fluids from a patient, or aspirating syringes for withdrawing medication from a container, etc.

[0044] The structure of an exemplary plunger rod 10 will now be described in detail. FIG. 3 is a perspective view of plunger rod 10. As shown, plunger rod 10 includes an elongate body 12 having a central axis 14 extending between a proximal end 16 and a distal end 18. In one exemplary embodiment, central axis 14 of plunger rod 10 may coincide with a corresponding central axis of syringe barrel 4. Elongate body 12 of plunger rod 10 has a proximal end 16, a distal end 18, a first curved end surface 20, a second curved end surface 22, and an interface portion 24 connecting first curved end surface 20 to second curved end surface 22. First curved end surface 20 and second curved end surface 22 may also be formed of straight segments or multiple corresponding adjacent segments. In one exemplary embodiment, first curved end surface 20, second curved end surface 22, and interface portion 24 each extend between proximal end 16 and distal end 18. In one configuration, at least the first curved end surface 20 and the second curved end surface 22 are both configured in a circle defined by the perimeter 40 (shown in FIG. 6) of the elongate body 12. As shown, the perimeter 40 may be discontinuous. As described below, the improved shape of the plunger rod 10 allows the plunger rod 10 to be manufactured using less material and molded in a shorter cycle time.

[0045] Continuing to refer to FIG. 3 , plunger rod 10 may optionally further include thumb depression portion 52 located at proximal end 16 of elongate body 12 and threaded coupling portion 62 located at distal end 18 of elongate body 12. Thumb depression portion 52 may include a portion wider than the interior of syringe barrel 4, providing a structure for a user to push against when advancing plunger rod 10 through syringe barrel 4. As shown in FIG. 3 , arcuate periphery 40 may be lower than the arcuate periphery of thumb depression portion 52. As shown in FIG. 2 , threaded coupling portion 62 may be threadably coupled to stopper 6. Alternatively, stopper 6 may also be clipped onto plunger rod 10, thereby allowing plunger rod 10 to advance through syringe barrel 4 as a combined assembly. Furthermore, stopper 6 is sized relative to syringe barrel 4 to provide a sealing engagement with the inner surface of the sidewall of syringe barrel 4. It is noted here that any suitable stopper 6 may be employed with the plunger rod of the present invention.

[0046] Elongated body 12 is at least partially disposed within syringe barrel 4 for the purpose of advancing stopper 6 through syringe barrel 4. In one embodiment, syringe barrel 4 may be in the general form of an elongated cylindrical barrel known in the art in the general shape of a hypodermic syringe. In alternative embodiments, syringe barrel 4 may be in other forms for containing a fluid for delivery. Syringe barrel 4 may be formed of glass or may be injection molded from a thermoplastic material such as polypropylene or polyethylene according to techniques known to those skilled in the art, although it will be understood that syringe barrel 4 may be made from other suitable materials and according to other application techniques.

[0047] In one example embodiment, as shown in FIG. 3 , plunger rod 10 further includes a plurality of support ribs (two support ribs 26, 28 are shown) extending from elongate body 12 between proximal end 16 and distal end 18. Support ribs 26, 28 may also extend radially, such as perpendicularly, relative to central axis 14, and plunger rods according to the disclosed concepts may include up to five ribs. In another example, as shown in FIG. 4 , plunger rod 80 includes one single support rib 96 extending from elongate body 82 between proximal end 86 and distal end 88. It will be appreciated that plunger rod 80 otherwise includes all of the same structural features and advantages as plunger rod 10. Support ribs 26, 28, and 96 advantageously function to strengthen and stabilize plunger rods 10, 80, thereby allowing them to move in and out of syringe barrel 4 without significant and undesirable bending.

[0048] FIG. 5 is a side view of the plunger rod 10, and FIG. 6 is a cross-sectional view of the plunger rod 10. As shown in FIG. 6, the interface portion 24 includes an intermediate surface 30, a first connecting surface (e.g., without limitation, a first angled surface 32) extending from the intermediate surface 30 to the first curved end surface 20, and a second connecting surface (e.g., without limitation, a second angled surface 34) extending from the intermediate surface 30 to the second curved end surface 22. The angled surfaces 32 and 34 may be curved or straight. The interface portion 24 at least partially defines an arcuate periphery 40 of the elongate body 12, which may be concave toward the central axis 14. In one example embodiment, the intermediate surface 30 and the curved end surfaces 20 and 22 together form a circle defined by the periphery of the elongate body. Furthermore, the intermediate surface 30 may be curved or straight. Accordingly, it will be understood that the arcuate periphery 40 may be discontinuous. Additionally, the first and second connecting surfaces may include first and second angled surfaces 32, 34, respectively, relative to the intermediate plane 30. More specifically, in one embodiment, the first and second angled surfaces 32, 34 each extend from the intermediate plane 30 at a respective angle θ1, θ2 that is equal to or greater than 90 degrees relative to the intermediate plane 30. Preferably, the angles θ1, θ2 are less than 120 degrees relative to the intermediate plane 30. Furthermore, in one configuration, none of the first curved end surface 20, the second curved end surface 22, and / or the interface portion 24 intersects with the central axis 14 of the elongate body 12 (which is depicted as a circle to represent an axis perpendicular to the page). Thus, in this configuration, the central axis 14 of the plunger rod 10 is free of material. It should be further noted that in certain embodiments, the first curved end surface 20 and the second curved end surface 22 do not intersect with each other, i.e., the first curved end surface 20 and the second curved end surface 22 do not form a continuous periphery.

[0049] In operation, the geometry of the plunger rod 10 provides it with many advantages over known plunger rods (such as, but not limited to, the plunger rod 110 shown in FIGS. 7 and 8 ). For example, by having discontinuous arcuate periphery 40 and having portions that do not intersect with one another, the elongated body 12 can advantageously be manufactured with less material than the conventional plunger rod 110. As shown in FIG. 8 , the conventional plunger rod 110 has a first planar portion 112 and a second planar portion 114 that intersects with the first planar portion 112 at a central region 116. In other words, the elongated body of the plunger rod 110 is generally cross-shaped, having two planar portions 112, 114 that intersect with one another at the central region 116. It can be readily appreciated that the central region 116 has an undesirably large amount of material due to the intersection of the first and second planar portions 112, 114. This is disadvantageous for at least the following reasons. First, the large amount of material present in this region results in a relatively high material cost for manufacturing plunger rod 110. Second, the time required for the large central region 116 to cool results in a relatively long cycle time associated with forming plunger rod 110.

[0050] The plunger rod 10 of the present invention solves these problems. First, by having material spaced around, but not at, the central axis 14, costs can be reduced by eliminating intersections or overlapping areas that could otherwise create large clumps. Furthermore, plunger rods 10, 80 having the inventive structure described herein are more resistant to bending (e.g., displacement away from the central axis 14) during travel within the syringe barrel 4 than conventional plunger rods 110, and can do so with significantly less material. Because of the improved resistance to breakage, plunger rods 10, 80 may be manufactured from different materials than plunger rod 110 (e.g., thermoplastic materials such as, but not limited to, polycarbonate materials, polypropylene, polystyrene, etc.).

[0051] The cycle time associated with manufacturing plunger rod 10 (e.g., plunger rod 80) can be advantageously reduced due to the elimination of relatively thick regions that may otherwise require long cooling times during molding. Furthermore, while less material is used in plunger rods 10, 80, structural and functional integrity is advantageously not compromised due to the improved geometry. Specifically, while less material is used to manufacture plunger rods 10, 80, the improved geometry, as shown in FIG. 6 , provides beneficial stability to aid in movement into and out of syringe barrel 4. The improved geometry maintains the functional attributes necessary to effect plunger operation, but advantageously significantly reduces material costs and cycle time. Furthermore, curved end surfaces 20, 22 and intermediate surface 30 are, in one embodiment, substantially equally spaced from one another along arcuate periphery 40 of elongated body 12. Additionally, by being angled surfaces, the angled surfaces 32, 34 advantageously define three substantially equally sized portions of the elongate body 12 when viewed in terms of FIG.

[0052] Table 1, reproduced below, shows 3D modeling data for different plunger rods, including a prior art "X-section" plunger rod and several "Ω-section" plunger rods (e.g., plunger rods 10 and 80) according to the disclosed concepts, where "Ω" refers to the overall cross-sectional shape of plunger rods 10 and 80, as shown in FIG. 6. "Thickness" refers to the maximum thickness of the PR's cross section (measured at the center of the cross for X-section PRs and at the rounded region for Ω-section PRs). In entries 3 through 6, "T" refers to the thickness of the PR in entry 2. The cross-sectional surface is measured anywhere on the PR except where the ribs are located. Compression and bending displacements were calculated through numerical simulations for an axial force of 10 N. In Table 1, #1 is the current X-section, #2 through #5 correspond to Ω-profiles with various combinations of thickness and number of ribs, and #6 represents the various shapes considered in the S-profile configuration. Table 1 reflects technical information such as cross-sectional surface (different from flange surface), main use results (applicable force indexed with X-shape as 100).

[0053] [Table 1]

[0054] Table 2, reproduced below, shows the % change relative to the reference X-shape for the same configurations as Table 1. This allows for easy comparison between configurations.

[0055] Configuration 2 offers three times the thumb force resistance at only a 14% price increase. This is very high performance for a limited cost increase. Configurations 3 and 4 offer twice the resistance at a 17% savings. This is high performance at a lower cost. Configuration 5 is 45% more resistant to X-shape #1 at 25% lower cost. This is improved performance at a very low cost. Configurations 3 and 4 show that the number of ribs does not have a significant impact on performance at this size. Configuration 6 shows slightly lower performance for a limited cost reduction. This solution is specialized for specific applications and sizes, typically plunger rods with small cross sections.

[0056] [Table 2]

[0057] In another exemplary embodiment of the disclosed concepts shown in Figure 9, interface portion 224 intersects central axis 214 and extends directly from first curved end surface 220 to second curved end surface 222. In the embodiment of Figure 9, the elongated body of plunger rod 210 has a generally S-shaped cross-section. It will be appreciated that plunger rod 210 otherwise functions substantially similarly to plunger rods 10, 80 described above and offers the same improvements over prior art plunger rod 110 (e.g., reduced material costs, shorter cycle times during molding).

[0058] Elements of one disclosed aspect can be combined with elements of one or more other disclosed aspects to form different combinations, all of which are considered within the scope of the present concepts.

[0059] While this disclosure has been described as having an exemplary design, the disclosure can be further modified within the spirit and scope of the disclosure. Accordingly, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the scope of the appended claims.

Claims

1. 1. A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising: an elongate body having a proximal end, a distal end opposite the proximal end, and a central axis extending between the proximal end and the distal end; a first curved end surface; a second curved end surface; and an interface portion joining the first curved end surface to the second curved end surface, wherein each of the first curved end surface, the second curved end surface, and the interface portion extends between the proximal end and the distal end; the central axis of the elongate body coincides with a corresponding central axis of the syringe barrel; the joining portion comprises an intermediate surface, a first connecting surface extending from the intermediate surface to the first curved end surface, and a second connecting surface extending from the intermediate surface to the second curved end surface; A plunger rod, wherein the intermediate surface, the first curved end surface, and the second curved end surface together define a discontinuous arcuate periphery of the elongate body, the discontinuous arcuate periphery being located on the same circumference.

2. The plunger rod of claim 1 , wherein the first connecting surface is at a first angle relative to the intermediate surface, and the second connecting surface is at a second angle relative to the intermediate surface.

3. 3. The plunger rod of claim 2, wherein the first angled surface and the second angled surface each extend at a respective angle greater than or equal to 90 degrees relative to the intermediate plane.

4. The plunger rod of claim 1 , wherein the first curved end surface, the second curved end surface, and the junction portion do not intersect with the central axis of the elongate body.

5. 1. A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising: an elongate body having a proximal end, a distal end opposite the proximal end, and a central axis extending between the proximal end and the distal end; a first curved end surface; a second curved end surface; and an interface portion joining the first curved end surface to the second curved end surface, wherein each of the first curved end surface, the second curved end surface, and the interface portion extends between the proximal end and the distal end; the central axis of the elongate body coincides with a corresponding central axis of the syringe barrel; the joint portion intersects the central axis and extends directly from the first curved end surface to the second curved end surface; A plunger rod, wherein the first curved end surface and the second curved end surface together define a discontinuous arcuate periphery of the elongate body, the discontinuous arcuate periphery lying on the same circle.

6. 6. The plunger rod of claim 5, wherein said elongate body has a generally S-shaped transverse cross section.

7. The plunger rod of claim 1 , wherein the plunger rod further comprises a plurality of support ribs extending from the elongate body between the proximal and distal ends.

8. a syringe assembly a syringe barrel having a sidewall, a distal end, and a proximal end; and A plunger rod, an elongate body having a proximal end, a distal end of the elongate body opposite the proximal end, and a central axis extending between the proximal end of the elongate body and the distal end of the elongate body; a first curved end surface; a second curved end surface; and an interface joining the first curved end surface to the second curved end surface, wherein each of the first curved end surface, the second curved end surface, and the interface extends between the proximal end of the elongate body and the distal end of the elongate body; a plunger rod; the central axis of the elongate body coincides with a corresponding central axis of the syringe barrel; the joining portion comprises an intermediate surface, a first connecting surface extending from the intermediate surface to the first curved end surface, and a second connecting surface extending from the intermediate surface to the second curved end surface; a syringe assembly, wherein the intermediate surface, the first curved end surface, and the second curved end surface together define a discontinuous arcuate periphery of the elongate body, the discontinuous arcuate periphery lying on the same circumference.

9. 9. The syringe assembly of claim 8, wherein the first connecting surface is at a first angle relative to the intermediate surface, and the second connecting surface is at a second angle relative to the intermediate surface.

10. 10. The syringe assembly of claim 9, wherein the first angled surface and the second angled surface each extend from the intermediate plane at an angle greater than or equal to 90 degrees relative to the intermediate plane.

11. 9. The syringe assembly of claim 8, wherein the first curved end surface, the second curved end surface, and the junction portion do not intersect with the central axis of the elongate body.

12. 9. The syringe assembly of claim 8, wherein said plunger rod further comprises a thumb depression disposed at said proximal end of said elongate body, said thumb depression being wider than said syringe barrel.

13. 9. The syringe assembly of claim 8, wherein the plunger rod further comprises a coupling portion disposed at the distal end, and the syringe assembly further comprises a stopper coupled to the coupling portion and disposed internally relative to the syringe barrel.

14. a syringe assembly a syringe barrel having a sidewall, a distal end, and a proximal end; and A plunger rod, an elongate body having a proximal end, a distal end opposite the proximal end, and a central axis extending between the proximal end of the elongate body and the distal end of the elongate body; a first curved end surface; a second curved end surface; and an interface joining the first curved end surface to the second curved end surface, wherein each of the first curved end surface, the second curved end surface, and the interface extends between the proximal end of the elongate body and the distal end of the elongate body; a plunger rod; the central axis of the elongate body coincides with a corresponding central axis of the syringe barrel; the joint portion intersects the central axis and extends directly from the first curved end surface to the second curved end surface; a syringe assembly, wherein the first curved end surface and the second curved end surface together define a discontinuous arcuate periphery of the elongate body, the discontinuous arcuate periphery lying on the same circumference.

15. 15. The syringe assembly of claim 14, wherein the elongate body has a generally S-shaped transverse cross-section.

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