JP2008307237A - Prefilled syringe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prefilled syringe where the connection between a plunger rod and a gasket does not slack off even when rotational force is given to the base of the plunger rod, and where the entire plunger can rotate only when rotational force is applied in the direction of screwing up them together. <P>SOLUTION: This is a prefilled syringe that has been charged with a liquid medicine and plugged up with a gasket. It includes a coupler screwed to the base end of the gasket, a bottom rod connected from the base end of the coupler, a stopper formed in the coupler, and an engagement part to be engaged with the stopper by turning the bottom rod in the direction of screwing it to the stopper. The prefilled syringe is characterized in that the stopper cannot be engaged with the engagement part because it is elastically deformed if any force is applied to it in its disengagement direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a prefilled syringe.

  A normal syringe is obtained by press-fitting a plunger rod into a gasket and assembling it in advance as a set, and then inserting the gasket into a barrel. On the other hand, a syringe filled with a chemical solution, that is, a prefilled syringe, is usually obtained by filling a barrel with a chemical solution and plugging the gasket and then connecting a plunger rod to the gasket. That is, a method of joining a plunger rod as a post-process to a syringe with a gasket plugged is adopted as a method for obtaining a prefilled syringe. The reason why this method is adopted is that if the plunger rod is attached to the gasket in advance, the plugging process for sealing the chemical solution becomes difficult.

Such a prefilled syringe gasket and plunger rod can be joined by using a gasket female screw formed of a rubber elastic material such as butyl rubber or elastomer, and a male plunger rod formed of plastic such as polypropylene. Screwing with screws is widely adopted. This is because when the plunger rod is press-fitted into the gasket as in the case of a normal syringe, the chemical solution may leak from the gasket or the tip nozzle.

One method of using a prefilled syringe is to set it in a syringe pump in order to control the dose of drug solution per unit time. The setting mechanism will be described by taking a normal syringe as shown in FIG. 23 as an example. The flange 32 at the proximal end of the barrel 3 and the flange 632 at the proximal end of the plunger rod R are respectively connected to the holder of the syringe pump and the slider. It is necessary to fit in the fixed groove. Some types of syringe pumps have a vertical slit for engaging the cross rib 631 with the slider. For such a model, the cross rib 631 of the plunger rod R is inserted into the vertical slit of the slider. In order to fix, the plunger rod R must be rotated and finely adjusted.

If the gasket and plunger rod are connected by press fitting like a normal syringe, there is no problem because the connection state of the gasket and plunger rod does not change even if the plunger rod is rotated. As described above, the gasket and the rod are connected by screwing the male screw and the female screw. Therefore, there is a possibility that the screwing may be loosened due to fine adjustment operation by rotation.

  When the screwing is loosened, there arises a problem that an accurate amount of the medical solution set by the syringe pump is not administered from inside the syringe. In addition, if there is a difference in height between the syringe pump and the administration position, the pressure in the syringe will be negative due to the difference in height, so if the screwing is loose, the rod will fall out of the gasket and the plunger rod will separate from the gasket. Therefore, since the administration speed is not controlled by the slider, there is a possibility that an excessive amount of the drug solution is administered in a short time (syphoning phenomenon).

In addition, it has been reported that the user unintentionally turns the plunger rod. Even if the plunger rod does not loosen during storage and transportation, the gasket and plan can be changed by the user's unconscious operation during use. The connection with the jar rod may be loosened.

In view of this, several syringes have been proposed in which the plunger rod and the gasket are unlikely to come off and the plunger rod can be assembled without being pressed into the gasket after being plugged. On the plunger having a ridge groove that bends in the circumferential direction from the axial direction to the side wall, the lower part of the plunger having a projection guided by the ridge groove is pushed along the ridge groove and rotated to be engaged, and further on the plunger A syringe provided with a plunger obtained by screwing a gasket with a gasket has been proposed (Patent Document 1).

  Further, the gasket has a screwed portion that can be screwed into a flange-like flange formed at the tip of the plunger rod inside the gasket, and a space formed at the tip of the screwed portion, and the tip of the plunger rod When the hook-shaped flange formed in the portion enters the space beyond the screwed portion, the hook-shaped flange is provided with a plunger configured to engage with the space in a loose-fit state, There has also been proposed a syringe that prevents external force acting on the plunger rod from being directly transmitted to the gasket (Patent Document 2).

JP2007-44159 JP 2002-272843 A

  However, in a plunger that is engaged along the groove as in Patent Document 1, there is a possibility that the plunger top and the plunger bottom may come off. In particular, when setting the syringe pump, if a rotational force is applied under the plunger, the protrusion at the lower end of the plunger also moves in the circumferential direction. May be located in the axial groove, and the bottom of the plunger may fall off the top of the plunger. However, if the upper and lower plungers are connected freely to each other, assembly is extremely difficult.

  In addition, in the case of a structure in which the flange-shaped flange formed at the distal end portion of the plunger rod enters the gasket space beyond the threaded portion as in Patent Document 2, the distal end of the plunger rod is a flange-shaped flange. Yes, since the thread is formed inside the gasket, the plunger rod shaft must be mounted while being inclined with respect to the gasket shaft. Therefore, for example, when using a manufacturing method in which the plunger rod is engaged with a gasket previously loaded in the syringe, such as a prefilled syringe, the plunger rod shaft cannot be tilted with respect to the gasket shaft. The plunger rod must be screwed in while distorting the screw groove with the hook-shaped flange, and since the distortion force is applied to the gasket, the liquid tightness may be deteriorated. Further, as a method of avoiding this, a method of making the bowl-shaped flange into a disk shape with a part cut off as shown in FIG. 6 of Patent Document 2 is also conceivable, but in this case, when the plunger rod is attached to the gasket If the plunger rod is rotated in the anti-screwing direction, the plunger rod may easily fall off from the gasket, which is not preferable.

  The plungers described in Patent Document 1 and Patent Document 2 described above can prevent the plunger rod from dropping from the gasket when a linear force acts on the plunger rod. However, these plungers do not cope with preventing the plunger rod from dropping from the gasket when a rotational force acts on the plunger rod.

  Considering the dropping of the plunger rod from the gasket due to the rotational force, it is not preferable to use a connection method in which the plunger rod is detachably connected to the gasket by the rotation of the plunger. On the other hand, considering the assembly of the plunger in the prefilled syringe, it is preferable that the gasket and the plunger rod can be connected by screwing, and the gasket is in close contact with the barrel when the prefilled syringe is stored. In some cases, if administration is attempted in this state, it is preferable that the gasket can be gently peeled off the barrel because the force for pushing the plunger in the initial movement is too strong and the liquid may be unexpectedly injected. Therefore, the plunger rod does not fall off the gasket by applying a rotational force, but it is also required that the rotational force can be transmitted to the gasket.

  The object of the present invention is easy to manufacture, and even if a rotational force is applied to the proximal end side of the plunger rod, the connection between the plunger rod and the gasket does not loosen and rotates in the screwing direction. The object is to provide a prefilled syringe in which the entire plunger is rotatable only when a force is applied.

Therefore, the present inventor has come up with the present invention as a result of intensive studies to solve the above-described problems. That is, the present invention is a prefilled syringe filled with a chemical solution inside, a barrel having a tip provided with an injection needle connecting portion sealed with a cap, and liquid-tight and slidably accommodated in the barrel. A gasket, a coupler screwed into the base end of the gasket, and a bottom rod connected from the base end side of the coupler,
The coupler is a prefilled syringe, which rotates following the bottom rod when the bottom rod is rotated in the screwing direction, but idles when the bottom rod is rotated in the anti-screwing direction.

  In particular, the coupler has an elastically deformable stopper, the bottom rod has an engaging portion that can be engaged with the stopper, and the coupler rotates the bottom rod in a screwing direction. When the engaging portion and the stopper are engaged, the follower rotates. When the bottom rod is rotated in the anti-screwing direction, the stopper is elastically deformed and does not engage with the engaging portion. It is said prefilled syringe characterized by idling.

  The bottom rod has an elastically deformable stopper, the coupler has an engaging portion that can be engaged with the stopper, and the coupler rotates the bottom rod in a screwing direction. When the stopper and the engaging portion are engaged, the follower rotates. When the bottom rod is rotated in the anti-screwing direction, the stopper is elastically deformed and does not engage with the engaging portion. It is said prefilled syringe characterized by idling.

  In the prefilled syringe, a housing portion is formed at a proximal end of the coupler, and the bottom rod is housed in the housing portion at a distal end side.

  A housing part is formed at the tip of the bottom rod, and the coupler is the prefilled syringe having a base end housed in the housing part.

  The pre-filled syringe according to the above, wherein the coupler is formed of two or more parts connected in the axial direction, and the connection of the parts constituting the coupler rotates following each other.

  The pre-filled syringe according to the above, wherein the bottom rod is formed of two or more parts connected in the axial direction, and the parts constituting the bottom rod rotate following each other. is there.

  The prefilled syringe of the present invention is formed of a coupler and a bottom rod in which a plunger rod is connected in the axial direction, and an engaging portion and a stopper are formed on the coupler and the bottom rod, and are connected so as to be able to rotate following only the screwing direction. Is done. Therefore, even if the bottom rod is rotated in the anti-screwing direction, the coupler is idle and does not rotate. Therefore, at the time of assembling the prefilled syringe, since it can be assembled by screwing the plunger rod into the gasket as in the conventional assembly, no special technique is required. Further, for example, even when the base end of the plunger rod is rotated when being set in the syringe pump, the connection between the gasket and the plunger rod is not loosened.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the exemplary embodiments described in these drawings.

  FIG. 1 is a diagram of an embodiment of the prefilled syringe of the present invention. FIG. 2 is a cross-sectional view of the prefilled syringe shown in FIG. FIG. 3 is a longitudinal sectional view of the distal end portion of the plunger of the prefilled syringe shown in FIG. FIG. 4 is a diagram showing an exploded state of the prefilled syringe shown in FIG. FIGS. 5A and 5B are a BB sectional view and a CC sectional view of the prefilled syringe disassembled state shown in FIG. 4, respectively. FIG. 6 is a longitudinal cross-sectional view of the tip of the coupler and bottom rod in the disassembled state of the prefilled syringe shown in FIG. FIGS. 7A to 7E are diagrams showing changes in the elastic deformation of the stopper when the bottom rod of the prefilled syringe shown in FIG. 1 is rotated in the anti-screwing direction. FIG. 8 is an enlarged view of the tip showing the connection between the gasket and the plunger rod of the prefilled syringe of the present invention. FIG. 9 is a diagram of another embodiment of the prefilled syringe of the present invention. 10 is a DD cross-sectional view of the prefilled syringe shown in FIG. 9. FIG. 11 is a longitudinal sectional view of the distal end portion of the plunger of the prefilled syringe shown in FIG. FIG. 12 is a diagram illustrating an exploded state of the prefilled syringe illustrated in FIG. 9. FIGS. 13A and 13B are an EE cross-sectional view and a FF cross-sectional view of the prefilled syringe disassembled state shown in FIG. 12, respectively. 14 is a longitudinal cross-sectional view of the coupler and the bottom rod tip in the disassembled state of the prefilled syringe shown in FIG. FIGS. 15A to 15E are diagrams showing changes in the elastic deformation of the stopper when the bottom rod of the prefilled syringe shown in FIG. 9 is rotated in the anti-screwing direction. FIG. 16 is a view of still another embodiment of the prefilled syringe of the present invention. FIG. 17 is a GG cross-sectional view of the prefilled syringe shown in FIG. 16. 18 is a longitudinal cross-sectional view of the plunger tip of the prefilled syringe shown in FIG. FIG. 19 is a diagram showing an exploded state of the prefilled syringe shown in FIG. 20 (a) and 20 (b) are an HH sectional view and a JJ sectional view, respectively, in the prefilled syringe disassembled state shown in FIG. FIG. 21 is a longitudinal sectional view of the front end of the coupler and bottom rod in the disassembled state of the prefilled syringe shown in FIG. 22A to 22E are diagrams showing changes in elastic deformation of the stopper when the bottom rod of the prefilled syringe shown in FIG. 16 is rotated in the anti-screwing direction. FIG. 23 is a partial cross-sectional view of a conventional syringe.

  One embodiment of the present invention will be described with reference to FIGS. 4 to 6 are views showing an exploded state of the prefilled syringe shown in FIG. The prefilled syringe 1 of the present invention has a barrel 3 having an injection needle connection portion 31 opened at the distal end, an opening at the proximal end, and a flange 32 provided at the outer wall of the proximal end. Is fitted with a cap 2 and the opening is sealed. A gasket 4 is housed in a liquid-tight and slidable manner from the base end of the barrel 3. A space partitioned by the cap 2 and the gasket 4 in the barrel 3 is filled with a chemical solution 7. A female screw 41 is formed at the base end of the gasket 4, and a coupler 5 having a male screw 51 screwed to the female screw 41 at the tip is connected to the base end of the gasket 4 by screwing. In the coupler 5, a gasket support portion 53 having a connection hole 52 is coaxially formed on the base end of the male screw 51, and a cylindrical housing portion 54 is formed on the base end side of the gasket support portion 53. An elastically deformable stopper 8 is formed on the side wall of the housing portion 54, and an engaging claw 81 formed toward the inside of the housing portion 54 is formed at the tip of the stopper 8. The bottom rod 6 and the coupler 5 are connected in the axial direction by projecting a protrusion 61 formed at the tip of the bottom rod 6 into the connection hole 52. In the bottom rod 6, a core portion 62 accommodated inside the accommodating portion 54 is formed at the base end of the protrusion 61, and a bottom rod main body 63 is formed at the base end of the core portion 62. At this time, the coupler 5 and the bottom rod 6 have different shafts depending on where the connecting hole 52 and the protrusion 61 are engaged, and where the base end of the accommodating portion 54 and the tip of the bottom rod body 63 are in contact with each other. It is connected and attached stably without blurring. The core portion 62 is provided with an engagement piece 9 serving as an engagement portion that engages with the stopper 8 by a rotation operation.

  The plunger rod R is formed of a coupler 5 and a bottom rod 6, and the bottom rod 6, which is a component at the base end of the plunger rod R, is connected to the coupler 5 with its axis aligned, and the bottom rod 6 has a core. The engaging piece 9 is formed in the part 62, and the coupler 5 is provided with a stopper 8 on the side wall of the accommodating part 54 so that the bottom rod 6 is engaged with the engaging piece 9 by rotating in the screwing direction. ing. As shown in FIGS. 7A to 7E, when the stopper 8 hits the engagement piece 9 in the counter-threading direction, the engagement claw 81 is pushed outward from the center by the engagement piece 9, and the stopper 8 The engagement piece 9 is not engaged. Therefore, even if the bottom rod 6 is rotated in the anti-screwing direction, the coupler 5 does not follow the bottom rod 6 and rotate. Thus, since the stopper 8 functions only when the bottom rod 6 is rotated in the screwing direction, even if a rotational force is applied to the base end of the plunger rod R, the plunger rod R and the gasket 4 are connected. Will not loosen. When rotating in the screwing direction, the coupler 5 and the bottom rod 6 are engaged according to the state shown in FIG. 7E, so that the plunger can be rotated as necessary. is there.

  The shape of the connecting hole 52 formed in the coupler 5 is formed into a tapered shape that gradually decreases in diameter from the proximal end side, and similarly, the protrusion 61 at the distal end of the bottom rod 6 is tapered so that the diameter is gradually reduced toward the distal end. Thus, when the coupler 5 and the bottom rod 6 are connected, the protrusion 61 formed at the tip of the bottom rod 6 into the connection hole 52 of the coupler 5 is facilitated. On the other hand, once coupled, the distal surface on the periphery of the coupling hole 52, which is a surface perpendicular to the axis, and the proximal surface of the protrusion 61 are engaged with each other. And the bottom rod 6 are not disconnected. Since the coupler 5 and the bottom rod 6 are rotatably connected as shown here, the bottom rod 6 is free to the coupler 5 as long as the stopper 8 and the engagement piece 9 are not engaged. Can be rotated.

  The gasket 4 is a rubber elastic body, and a material exhibiting rubber elasticity used for a normal syringe gasket can be used. Since the rubber elastic body is liquid-tight, butyl rubber, butadiene rubber, isoprene rubber, silicone rubber, thermoplastic elastomer, silicone elastomer, or the like can be used.

  The material used for the plunger rod R is not particularly limited as long as it can be used for a syringe and can give the stopper 8 a slight elasticity, and a known material can be used. A thermoplastic resin is preferred because it is easy to mold. At this time, all the materials of the plunger rod R may not be the same.

  As shown in FIG. 8, with respect to the connection between the gasket 4 and the plunger rod R, an engagement convex portion 511 is provided on the top surface of the coupler 5 and the base end portion of the male screw 51, and the engagement convex portion is provided at the base end of the gasket 4. An engagement recess 42 that engages with the portion 511 may be provided. In addition to the threaded engagement of the male screw 51 and the female screw 41, the engagement convex portion 511 and the engagement recess 42 engage with each other, whereby the gasket 4 and the plunger rod R are more firmly connected and are not easily detached. .

  Next, another embodiment of the present invention will be described with reference to FIGS. 12 to 14 are views showing an exploded state of the prefilled syringe shown in FIG. An accommodating portion 54 is formed on the base end side of the coupler 5, and a stopper 8 is suspended from the top surface of the accommodating portion 54 toward the proximal end. An engagement piece 9 that engages with the stopper 8 by a rotation operation is formed in the core portion 62 that is located in the housing portion 54 and that is on the distal end side of the bottom rod 6. Also in the prefilled syringe shown in FIG. 9, when the bottom rod 6 is rotated in the screwing direction, the tip of the stopper 8 is engaged with the engagement piece 9, but when the bottom rod 6 is rotated in the anti-screwing direction. As shown in FIGS. 15A to 15E, the stopper 8 is elastically deformed from the center to the outside, so that the stopper 8 and the engagement piece 9 are not engaged. On the other hand, when rotated in the screwing direction, the coupler 5 and the bottom rod 6 are engaged according to the state shown in FIG. 15E, so that the plunger can be rotated as necessary. It is.

  Furthermore, another embodiment of the present invention will be described with reference to FIGS. 19 to 21 are views showing an exploded state of the prefilled syringe shown in FIG. An accommodation portion 54 is formed on the base end side of the coupler 5, and an engagement piece 9 is formed on the inner wall side portion of the accommodation portion 54. An S-shaped stopper 8 that engages with the engagement piece 9 by a rotation operation is formed in the core portion 62 that is located in the housing portion 54 and that is the distal end side of the bottom rod 6. Also in the prefilled syringe shown in FIG. 16, when the bottom rod 6 is rotated in the screwing direction, the tip of the stopper 8 is engaged with the engagement piece 9, but when the bottom rod 6 is rotated in the anti-screwing direction. Since the stopper 8 is elastically deformed so as to shrink toward the center as shown in FIGS. 22A to 22E, the stopper 8 and the engagement piece 9 are not engaged. On the contrary, when rotating in the screwing direction, the coupler 5 and the bottom rod 6 are engaged according to the state shown in FIG. 22 (e), so that the plunger can be rotated as necessary. It is.

  As shown in these embodiment examples, the prefilled syringe of the present invention connects a coupler and a bottom rod, and engages one of the coupler and the bottom rod with an engaging piece and the other with a screwing direction. A stopper is provided that engages with the mating piece. That is, the coupler and the bottom rod are free to rotate as long as the stopper does not engage with the engaging piece. Therefore, even if a rotational force in the anti-screwing direction is applied to the base end of the plunger rod, the coupler does not follow and rotate. Therefore, the connection between the gasket and the plunger rod does not loosen or come off. Also, for example, when the gasket is in close contact with the barrel, it is possible to rotate the plunger without affecting the connection by applying a rotational force in the screwing direction in situations where it is desired to rotate the gasket. is there.

  In addition, in these embodiment examples, the accommodating portion is formed in the coupler, but the accommodating portion may be formed on the bottom rod distal end side and the coupler proximal end side may be accommodated in the accommodating portion. Further, even if the housing portion is not formed in any of the components, the housing portion may not be formed as long as the above-described mechanism that rotates following only the screwing direction can be achieved.

  In the assembly process of the prefilled syringe of the present invention, if the plunger rod is assembled by connecting the coupler and the bottom rod in advance, then the plunger rod is plugged with a gasket as in the conventional prefilled syringe assembly method. The prefilled syringe can be obtained by moving into the barrel filled with the chemical solution and screwing the gasket and the coupler while rotating the barrel. Therefore, it is possible to assemble the plunger without requiring a special process and without press-fitting to the gasket.

  In the coupling process of the coupler and the gasket, the plunger rod may be rotated and the barrel may be fixed, or may be assembled by rotating both in some cases. Further, instead of moving the plunger rod into the barrel, the plunger rod may be introduced into the barrel by moving the barrel.

  The plunger rod of the prefilled syringe shown in these example embodiments is composed of two parts that are connected in the axial direction, that is, a plunger rod part and a bottom rod part. It may be composed of three or more parts, and the coupler and the bottom rod may be formed by connecting a plurality of parts in the axial direction. However, when the coupler or the bottom rod is composed of a plurality of parts, the coupling mechanism between the couplers or the bottom rods must be integrated by assembly or a mechanism that rotates following each other.

  By adopting the prefilled syringe structure, even if a rotational force is applied to the proximal end side of the plunger rod, the connection between the plunger rod and the gasket is not loosened, and the rotational force is applied in the screwing direction. Only when this is done can the entire plunger be rotated. Therefore, for example, when setting a prefilled syringe to a syringe pump, for example, even if the proximal end of the plunger rod is rotated, the connection between the gasket and the plunger rod is not loosened. The manufacturing process of the conventional prefilled syringe can be utilized.

The figure of the one embodiment example of the prefilled syringe of this invention. AA sectional drawing of the prefilled syringe shown by FIG. The longitudinal cross-sectional view of the plunger front-end | tip part of the prefilled syringe shown by FIG. The figure which shows the decomposition | disassembly state of the prefilled syringe shown by FIG. BB sectional drawing and CC sectional drawing of the prefilled syringe decomposition | disassembly state shown by FIG. The longitudinal cross-sectional view of the coupler and bottom rod front-end | tip part of the prefilled syringe decomposition | disassembly state shown by FIG. The figure which shows the elastic deformation change of the stopper at the time of rotating the bottom rod of the prefilled syringe shown by FIG. 4 in the anti-screwing direction. The front-end enlarged view which shows connection with the gasket and plunger rod of the prefilled syringe of this invention. The figure of the other embodiment example of the prefilled syringe of this invention. It is DD sectional drawing of the prefilled syringe shown by FIG. The longitudinal cross-sectional view of the plunger front-end | tip part of the prefilled syringe shown by FIG. The figure which shows the decomposition | disassembly state of the prefilled syringe shown by FIG. EE sectional drawing and FF sectional drawing of the prefilled syringe decomposition | disassembly state shown by FIG. The longitudinal cross-sectional view of the coupler and bottom rod front-end | tip part of the prefilled syringe decomposition | disassembly state shown by FIG. The figure which shows the elastic deformation change of the stopper at the time of rotating the bottom rod of the prefilled syringe shown by FIG. 9 in the anti-screwing direction. The figure of another one embodiment of the prefilled syringe of this invention. GG sectional drawing of the prefilled syringe shown by FIG. The longitudinal cross-sectional view of the plunger front-end | tip part of the prefilled syringe shown by FIG. The figure which shows the decomposition | disassembly state of the prefilled syringe shown by FIG. The HH sectional view and JJ sectional view of the prefilled syringe decomposition state shown in FIG. The longitudinal cross-sectional view of a coupler and the bottom rod front-end | tip part of the prefilled syringe decomposition | disassembly state shown by FIG. The figure which shows the elastic deformation change of the stopper at the time of rotating the bottom rod of the prefilled syringe shown by FIG. 16 in the anti-screwing direction. The fragmentary sectional view of the conventional syringe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prefilled syringe 2 Cap 3 Barrel 31 Injection needle connection part 32 Flange 4 Gasket 41 Female screw 42 Engagement recessed part 5 Coupler 51 Male screw 511 Engagement convex part 52 Connection hole 53 Gasket support part 54 Storage part 6 Bottom rod 61 Projection 62 Core portion 63 Bottom rod body 631 Cross rib 632 鍔 7 Chemical solution 8 Stopper 81 Engaging claw 9 Engaging piece R Plunger rod

Claims (7)

A prefilled syringe filled with a chemical solution,
A barrel having a tip provided with a needle connection sealed with a cap;
A gasket that is liquid-tight and slidably accommodated in the barrel;
A coupler screwed into the proximal end of the gasket;
A bottom rod connected from the base end side of the coupler,
The pre-filled syringe is characterized in that the coupler rotates following the bottom rod when the bottom rod is rotated in the screwing direction, but idles when the bottom rod is rotated in the anti-screwing direction. The coupler has an elastically deformable stopper,
The bottom rod has an engaging portion that can engage with the stopper,
When the coupler rotates the bottom rod in the screwing direction, the engagement portion and the stopper follow and rotate, but when the bottom rod rotates in the anti-screwing direction, The prefilled syringe according to claim 1, wherein the stopper is idled by being elastically deformed and not engaging with the engaging portion. The bottom rod has an elastically deformable stopper,
The coupler has an engaging portion that can engage with the stopper,
When the coupler rotates the bottom rod in the screwing direction, the stopper and the engaging portion are engaged to rotate, and when the bottom rod is rotated in the anti-screwing direction, The prefilled syringe according to claim 1, wherein the stopper is idled by being elastically deformed and not engaging with the engaging portion. A receiving portion is formed at the base end of the coupler,
The bottom rod is configured such that the distal end side is accommodated in the accommodating portion.
The prefilled syringe according to claim 2 or 3. A receiving portion is formed at the tip of the bottom rod,
The coupler is configured such that a base end side is accommodated in the accommodating portion.
The prefilled syringe according to claim 2 or 3.   6. The coupler according to claim 1, wherein the coupler is formed of two or more parts connected in the axial direction, and the connection of the parts constituting the coupler rotates following each other. The prefilled syringe as described.   The bottom rod is formed of two or more parts connected in the axial direction, and the parts constituting the bottom rod rotate following each other. A prefilled syringe according to crab.

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