Plunger Rod Comprising at Least Three Annular Elements for a Prefilled Syringe

Abstract

A prefilled syringe includes a syringe body filled with a medical fluid, which has a nozzle at a front side, the nozzle being closed with a cap, and which is closed at a rear side with a displaceable plunger; and a plunger rod that can be inserted into the syringe body via the rear side. The plunger rod has a connecting portion at a front side, via whi9ch the plunger rod can be connected to the plunger. At least three annular elements, which extend at least in some sections about a longitudinal axis of the rod, are arranged on a rear side of the connecting portion on the plunger rod in such a manner that they are located in the syringe body when the plunger rod is fully connected to the plunger. The three annular elements support a coaxial connection of the rod to the plunger positioned in the syringe.

Claims

1. A prefilled syringe comprising a syringe body which is filled with a medical fluid and comprises on a front end a nozzle, which is closed by way of a cap, and is closed on a rear end by way of a displaceable plunger, and a plunger rod which is insertable into the syringe body via the rear end and comprises on a front end a connecting portion, by means of which the plunger rod is connectable to the plunger, wherein at least three annular elements, which extend at least in portions about a longitudinal axis of the plunger rod, are arranged on the plunger rod on a rear end of the connecting portion such that when the plunger rod is fully connected to the plunger, the at least three annular elements are situated in the syringe body.

2. The prefilled syringe as claimed in claim 1, wherein a position of the plunger in the prefilled syringe body and the position of the at least three annular elements on the plunger rod are matched to one another such that in a first step, when the plunger rod is placed by way of its connecting portion on the plunger, two of the at least three annular elements are arranged in the interior of the syringe body.

3. The prefilled syringe as claimed in claim 1, wherein an outside diameter (D) of the at least three annular elements and an inside diameter of the syringe body are selected to enable the at least three annular elements to engage the syringe body to permit guiding the plunger rod in the syringe body.

4. The prefilled syringe as claimed in claim 1, wherein the outside diameter (D) of the at least three annular elements is identical.

5. The prefilled syringe as claimed in claim 1, wherein wing elements, extend radially outwardly and connect the at least three annular elements together, the wing elements being arranged distributed over a circumference of the plunger rod.

6. The prefilled syringe as claimed in claim 1, wherein at least four of the wing elements are arranged, to form angles therebetween, each angle being 90, wherein the at least four of the wing elements are arranged between two of the at least three annular elements.

7. The prefilled syringe as claimed in claim 5, wherein an outside diameter (D.sub.F) of the wing elements is selected to enable the wing elements to engage the syringe body.

8. The prefilled syringe as claimed in claim 5, wherein an outside diameter (D.sub.F) of the wing elements is substantially the same as the outside diameter (D) of the at least three annular elements.

9. The prefilled syringe as claimed in claim 5, wherein an outside diameter (D.sub.F) of the wing elements is smaller than an outside diameter (D) of the at least three annular elements.

10. The prefilled syringe as claimed in claim 5, wherein an outside diameter (D.sub.F) of the wing elements is less than an outside diameter (D) of the at least three annular elements by between 1 mm and 10 mm.

11. The prefilled syringe as claimed in claim 1, wherein the plunger rod is premounted on the plunger.

12. The prefilled syringe as claimed in claim 1, wherein the plunger rod is located next to the syringe body in an oxygen-impermeable, over pack.

13. An oxygen-impermeable over pack having an interior in which the syringe as claimed in claim 1, wherein it is hermetically enclosed.

14. A plunger rod for a prefilled syringe as claimed in claim 1, including a front-end connecting portion, the plunger rod being connectable to a plunger, wherein the at least three annular elements, extend at least in portions about a longitudinal axis of the plunger rod and are arranged at a distance R, wherein 0.5 mmR20 mm.

15. A pre-filled syringe as claimed in claim 1, the pre-filled syringe including a plunger positionable in the syringe body and the at least three annular elements are arranged on the plunger rod such that, when the plunger rod is fully connected to the plunger, the at least three annular elements are situated in the syringe body.

16. The prefilled syringe as claimed in claim 2, wherein an outside diameter (D) of the at least three annular elements and an inside diameter of the syringe body are selected to enable the at least three annular elements to engage the syringe body.

17. The prefilled syringe as claimed in claim 2, wherein an outside diameter (D) of the at least three annular elements is identical.

18. The prefilled syringe as claimed in claim 2, wherein wing elements, which extend radially outwardly and connect the at least three annular elements together, are arranged distributed over a circumference of the plunger rod.

19. The prefilled syringe as claimed in claim 2, wherein at least four wing elements are arranged to form angles therebetween, each angle being 90, wherein the at least four of the wing elements are arranged between two of the at least three annular elements.

20. The prefilled syringe as claimed in claim 5, wherein the wing elements are individually arranged between the at least three annular elements.

21. The prefilled syringe as claimed in claim 5, wherein an outside diameter (D.sub.F) of the wing elements is less than an outside diameter (D) of the at least three annular elements by between 4 mm and 8 mm.

22. A plunger rod for a prefilled syringe as claimed in claim 1, including a front-end connecting portion, the plunger rod being connectable to a plunger, wherein the at least three annular elements extend at least in portions about a longitudinal axis of the plunger rod and are arranged at a distance R, wherein 1 mmR10 mm.

23. The prefilled syringe as claimed in claim 18, wherein the wing elements are individually arranged between the at least three annular elements.

24. An oxygen-impermeable overpack comprising: a prefilled syringe and a plunger rod; wherein the prefilled syringe and the plunger rod are hermetically enclosed within an interior of the oxygen-impermeable overpack; the plunger rod including a front-end connecting portion by means of which the plunger rod is connectable to a plunger, wherein at least three annular elements which extend at least in portions about a longitudinal axis of the plunger rod and which are arranged on a rear end of the connecting portion at a distance R, wherein 0.5 mmR20 mm.

25. A plunger rod for a prefilled syringe, the plunger rod comprising a front-end connecting portion, by means of which the plunger rod is connectable to a plunger, wherein at least three annular elements which extend at least in portions about a longitudinal axis of the plunger rod and which are arranged on a rear end of the connecting portion at a distance R, wherein 0.5 mmR20 mm.

Description

[0019] The invention is described in detail below by way of exemplary embodiments in connection with the drawings, in which:

[0020] FIG. 1.a shows a side view of a plunger rod according to a first embodiment of the invention;

[0021] FIG. 1.b shows a side view of a prefilled syringe according to the invention with the plunger rod from FIG. 1.a;

[0022] FIG. 2.a shows a side view of a plunger rod according to a second embodiment of the invention;

[0023] FIG. 2.b shows a side view of a prefilled syringe according to the invention with the plunger rod from FIG. 2.a;

[0024] FIG. 2.c shows a perspective view of the plunger rod according to the second embodiment of the invention from FIG. 2.a;

[0025] FIG. 3 shows a perspective view of a plunger rod according to a third embodiment of the invention and

[0026] FIG. 4 shows a perspective view of a plunger rod according to a fourth embodiment of the invention.

[0027] FIG. 1.a shows a plunger rod 15 according to a first embodiment of the invention. The plunger rod 15 has a substantially cross-shaped cross section and is formed by the two legs 3. Stabilizing elements 7 are mounted along the longitudinal axis. The rear end of the plunger rod 15 is closed off by a flange 4 with a larger diameter. The notches 5 provided on the rear end enable the plunger rod 15 (as a component part of the syringe 20) to be operated in a syringe pump. The plunger rod 15 is designed for operation in a syringe 20 with a holding volume of between approximately 50 ml and 70 ml. A graduation 6 to 50 ml is provided on the plunger rod 15. The plunger rod 15 has a diameter D where 25 mmD30 mm and/or a length L where 100 mmL150 mm.

[0028] The front end of the plunger rod 15 is provided by a connecting portion 1, by means of which the plunger rod 15 is connected to a plunger 12, not shown here, (see FIG. 1.b in this respect). The connecting portion 1 is provided here, as an example, by a screw thread. Three annular elements 2a, 2b, 2c connect to the rear end of the connecting portion 1. As a result, when the plunger rod 15 is screwed into the plunger 12, it is possible, in particular, for the user to have haptic and/or acoustic control. The annular elements 2a, 2b, 2c preferably extend over the entire circumference of the plunger 15. The front annular element 2a additionally forms the stop when the plunger rod 15 is screwed into the plunger 12. The three annular elements 2a, 2b, 2c are preferably arranged equidistantly with respect to one another. In one embodiment, the three annular elements 2a, 2b, 2c are arranged individually at a distance R of between 2 mm and 8 mm with respect to one another. The annular elements 2a, 2b, 2c have for example, a thickness of approximately between 0.5 mm and approximately 5 mm, preferably of approximately between 1 mm and approximately 3 mm.

[0029] The cross-shaped cross section of the plunger rod 15 is also continued between the three annular elements 2a, 2b, 2c. Ignoring the flange 4 and the connecting portion 1, the diameter D of the plunger rod is identical or substantially identical along the longitudinal axis. As a result, so-called wing elements 3a, 3b or ribs are formed between the three annular elements 2a, 2b, 2c. The front, here four, wing elements 3a connect the front ring 2a to the central ring 2b. The rear, here four, wing elements 3b connect the central ring 2b to the rear ring 2b. The annular elements 2a, 2b, 2c and the wing elements 3a, 3b enable the plunger rod 15 to be guided into the syringe body 8 in as coaxial a manner as possible and, as a result, enable the plunger rod 15 to be screwed into the plunger 12 in as coaxial a manner as possible (see FIG. 1.b in this respect). Placing the plunger rod 15 on the plunger 12 at an angle, leading to possible tilting of the plunger 12 and finally possibly to resultant leakage can be reduced or even avoided as a result.

[0030] FIG. 1.b illustrates the use of the plunger rod 15 from FIG. 1.a in a prefilled syringe 20. The syringe 20 includes a syringe body 8 with a nozzle 9 arranged on the front end of the syringe body 8, a cap 11 closing the nozzle 9, a plunger 12 which is arranged in the syringe body 8 and closes the interior of the syringe body 8 in a fluid-tight manner, and the plunger rod 15 from FIG. 1a which is connected to the plunger 12 by means of its connecting portion 1. The connection between the plunger 12 and the plunger rod 15 is provided here by means of a screw connection. A thread, which is, however, not shown in the figure, is also provided in a corresponding manner in the interior of the plunger 12.

[0031] The outside diameter D or D.sub.F of the plunger rod 15 and/or of the annular elements 2a, 2b, 2c and/or of the wing elements 3a, 3b can be identical to the inside diameter of the syringe body 8. In order to make it easier for the plunger rod 15 to move in the syringe body 8, the outside diameter D or D.sub.F of the plunger rod 15 and/or of the annular elements 2a, 2b, 2c and/or of the wing elements 3a, 3b is, in particular, smaller than the inside diameter of the syringe body 8. The outside diameter D or D.sub.F is preferably reduced in relation to the inside diameter of the syringe body 8 by approximately between 0.5 mm and 5 mm.

[0032] The prefilled syringe 20 can be filled, for example, via its initially open rear end and then can be closed by way of the plunger 12. The plunger rod 15 can then be connected to the plunger 12 at a later point in time, for example shortly before the application. However, the plunger 12 can also, for example, be inserted into the syringe body 8 with the plunger rod 15 already screwed into the plunger 12.

[0033] The position of the plunger 12 in the prefilled syringe body 8 and the position of the three annular elements 2a, 2b, 2c on the plunger rod 15 are preferably matched to one another in such a manner that in a first step, when the plunger rod 15 is placed on the plunger 12 by way of its connecting portion 1, the two front rings 2a, 2b are already arranged in the interior of the syringe body 8 and are preferably guided by the inner side of the syringe body 8. When being screwed in, the plunger rod 15 is initially guided by the two front annular elements 2a, 2b and the front wing elements 3a and then also by the rear wing elements 3b in the syringe body 8. The rear third ring 2c supports the guiding of the plunger rod 15 in the final, fixed connection between the plunger rod 15 and the plunger 12. The three rings 2a, 2b, 2c are positioned in the interior of the syringe body 8 no later than in the state in which the plunger rod 15 is fully connected to the plunger 12, preferably is screwed into the plunger 12. The annular elements 2a, 2b, 2c prove to be advantageous as they prevent tilting over the entire circumference of 360. The wing elements 3a, 3b prove to be advantageous as they enable longer guidance along the longitudinal axis of the plunger rod 15. The present invention joins said advantages together.

[0034] FIGS. 2.a to 2.c show a plunger rod 15 according to a second embodiment of the invention. Only the differences to the plunger rod 15 from FIG. 1.a are explained below. For all the other components, reference is made to the preceding description concerning FIG. 1.a. The plunger rod 15 does not have a graduation. In contrast to the embodiment shown in FIG. 1.a, the wing elements 3a, 3b, which connect the three annular elements 2a, 2b, 2c together, do not have the identical outside diameter as the three annular elements 2a, 2b, 2c. The outside diameter D.sub.F of the wing elements 3a, 3b is smaller than the outside diameter D of the three annular elements 2a, 2b, 2c. The outside diameter D.sub.F of the wing elements 3a, 3b is preferably reduced by approximately between 4 mm and 8 mm in relation to the outside diameter D of the annular elements 2a, 2b, 2c. In the present case, there are precisely three annular elements which are located in the front region of the plunger rod 15.

[0035] As a result, when screwing the plunger rod 15 into the plunger 12, it is possible, in particular, for the user to have haptic and/or acoustic control. If the user screws the plunger rod 15 correctly into the plunger 12 immediately, he does not receive a haptic and/or acoustic message. If, in contrast, the user tries, unintentionally, to screw the plunger rod 15 into the plunger 12 incorrectly askew, he is able to perceive, in particular, the transition of the plunger rod 15 from the central annular element 2b to the rear annular element 2c on the edge 14 in the rear syringe body opening (see FIG. 2.b in this respect) as a type of jump, preferably connected to a type of click. As a result, the user is able to recognize that he is trying to connect the plunger rod 15 incorrectly to the plunger 12 and then he can correct the position of the plunger rod 15 in a corresponding manner.

[0036] In addition, FIG. 3 shows a plunger rod 15 according to a third embodiment of the invention. The design of said plunger rod 15 corresponds substantially to the design of the plunger rod 15 from FIGS. 2.a to 2.c. The present plunger rod 15 simply comprises different dimensions as it is designed for a syringe 20 with a holding volume of between approximately 20 ml and 30 ml. The plunger rod 15 has a diameter D where 13 mmD23 mm and/or a length L where 100 mmL150 mm. The distance R between the annular elements here is also 2 mmR8 mm.

[0037] Finally, FIG. 4 shows a plunger rod 15 according to a fourth embodiment of the invention. The design of said plunger rod 15 corresponds substantially to the design of the plunger rods 15 and 15 from FIGS. 2.a to 2.c and 3. The present plunger rod 15 simply comprises different dimensions as it is designed for a syringe 20 with a holding volume of between approximately 10 ml and 15 ml. The plunger rod 15 has a diameter D where 8 mmD18 mm and/or a length L where 80 mmL110 mm. The distance R between the annular elements here is 2 mmR8 mm. In addition, no stabilizing elements 7 are provided on the plunger rod 15.

[0038] It is clear to the person skilled in the art that the described embodiments are to be understood as examples. The invention is not limited to said embodiments but can be varied in many different ways without departing from the essence of the invention. Features of individual embodiments and the features named in the general part of the description can be combined with one another both individually and together.