JPH09308689A - Plunger having projection and syringe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate a plunger from a syringe and to rationally abandon the syringe by bonding a gasket through the male screw of the plunger and the female screw of a gasket and forming one projection on the top end face of the plunger in contact with the inner bottom face of the gasket at least. SOLUTION: The male screw is formed at the top end part of a plunger 1 and this is screwed with the female screw formed on the inside face of a gasket 10 so that the syringe and the plunger 1 can be easily separated. Besides, concerning the plunger 1, a projection 2 is formed on a top end face 3 in contact with the inner bottom face of the gasket 10. This projection 2 is formed while being inclined so that a top end 4 can be made oblique upward the right side in the case of syringer for turning the plunger 1 to right at the time of bonding the plunger 1 with the gasket 10. Thus, when turning and fastening the plunger 1 to right, the top end 4 of the projection 2 is engaged into the inner bottom face of the gasket 10, and the plunger 1 is surely fixed with the gasket 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger of an injector which is used by joining a gasket to a tip end portion thereof. A protrusion is provided on the tip end surface which is in contact with the inner bottom surface of the gasket so that the gasket and the plunger can be easily attached and detached. The present invention relates to a plunger having the plunger and a syringe provided with the plunger.

[0002]

2. Description of the Related Art In pharmaceutical products, there are many injections provided by a syringe filled with a drug solution (hereinafter referred to as a prefilled syringe). There are four methods for joining the plunger and the rubber gasket in those syringes, which are usually (1) fitting type, (2) screw type, (3) adhesive type and (4) integrally molded type shown in FIG. Is often used.

In the case of radiopharmaceuticals, it is preferable to separate the syringe from the plunger for the purpose of separating waste when the syringe is disposed of after use and reducing the amount of radioactive waste. In addition, since a special plunger using a radioactive shielding material that shields radiation is expensive, it is usually used repeatedly instead of being disposable. Further, the transport container can be downsized by facilitating the attachment / detachment of the plunger and mounting the plunger only when in use. For this reason, the screw method that can separate the plunger and the gasket is most often used as the method for joining the plunger and the gasket.

[0004]

As described above, there is a tendency for the syringe and the plunger to be easily separated after use. However, currently commercially available syringes have a structure in which it is difficult to separate the plunger from the gasket even if the gasket and plunger are joined by their respective screws, or the plunger gets caught in the gasket. Is the most. Screw the metal or plastic plunger into the gasket made of rubber or elastomer,
After the drug was administered, even if the plunger was rotated to remove the plunger, the plunger co-rotated with the gasket in the barrel of the syringe, which often prevented separation.

In the present specification, "bite" means a state in which the plunger and the gasket become integral with each other for some reason when the plunger and the gasket are joined, and the plunger cannot be separated from the gasket. To do. Also, "pushing in" means that when the plunger is joined to the gasket, the protrusion of the plunger is pressed against the inner bottom surface of the gasket and cannot be easily removed. It means that the protrusion of the jar easily comes off from the gasket.

In the case of radiopharmaceuticals, the inability to separate the plunger from the gasket after administration of the radiopharmaceutical means that the gasket is in direct contact with the drug inside the syringe, which is contaminated by radiation when the syringe is discarded. This will result in the disposal of the missing plunger, which will result in an unnecessarily large amount of radioactive waste. Further, if the plunger is forcibly removed when it has been caught in the gasket, there is a risk that the syringe will be damaged or the worker's exposure dose will increase.

The reason why the plunger and the gasket rotate together when the plunger is separated is that when the plunger is screwed into the gasket, a strong crimping force is applied to the tip surface or the screw surface of the plunger due to the elasticity of the gasket. Occurs. Silicone oil is applied to the inside of the barrel of the syringe to ensure the slidability of the gasket, so it is difficult for the gasket to slip and be fixed. Inappropriate screw shape. And so on.

The present invention has been completed in view of the above circumstances, and is a prefilled syringe for medicines, in which the gasket and the plunger can be joined by a screw type, and the plunger is rotated in a direction to remove the screw after drug administration. Thus, it is an object of the present invention to provide a syringe in which the plunger can be easily separated from the syringe.

[0009]

SUMMARY OF THE INVENTION The present invention is a plunger of a syringe which is used by joining a gasket to a distal end portion, the plunger being joined to the gasket by a male screw of the plunger and a female screw of the gasket. In addition, the plunger for a syringe is characterized in that it has at least one protrusion on the tip end surface of the plunger that is in contact with the inner bottom surface of the gasket.

The present invention also provides a syringe comprising a plunger having at least one protrusion on a tip end surface which contacts the inner bottom surface of the gasket.

Further, according to the present invention, in a syringe having a plunger having at least one protrusion on a tip surface contacting the inner bottom surface of the gasket, the gasket is obtained by rotating the plunger in the same direction as the tip direction of the protrusion. Provided is a method for attaching and detaching a gasket and a plunger, which are joined together and then separated from the gasket by rotating the plunger in the opposite direction.

The plunger of the present invention will be described with reference to the drawings. A male screw is formed on the tip of the plunger 1, and the plunger 1 is joined to the female screw formed on the inner surface of the gasket 10. The plunger 1 is characterized in that a protrusion 2 is provided on a tip surface 3 that contacts the inner bottom surface 11 of the gasket 10. The projection 2 is adhesively molded or integrally molded with the plunger, but the integrally molding is advantageous in terms of cost because the manufacturing process is simplified. The number of the protrusions 2 may be plural.

As described above, the gasket 10 has an internal thread formed on the inner side surface thereof, and the inner bottom surface 11 of the gasket 10 contacting the tip surface 3 of the plunger 1 is formed into a flat surface. The recess corresponding to the shape of the protrusion 2 of the plunger 1 is a gasket 1
It is not necessary to form the inner bottom surface 11 of 0. By thus forming the inner bottom surface 11 into a flat surface, the projection 2 of the plunger 1 is hard to fit into the inner bottom surface 11 of the gasket 10, and the plunger 1 and the gasket 10 are reliably joined.

The protrusion 2 of the plunger 1 of the present invention is directional. That is, in the case of a syringe in which the plunger 1 is rotated clockwise when the plunger 1 is joined to the gasket 10, the protrusion 2 is formed with an inclination such that the tip 4 thereof rises to the right. With such a structure, when the plunger 1 is tightened in the clockwise direction, the tip 4 of the protrusion 2 is pushed into the inner bottom surface 11 of the gasket 10, and the tip 4 is pressed against the gasket to be securely fixed, and at the same time, the left side When loosened around, the tip 4 is connected to the inclined surface of the protrusion 2, so the inner bottom surface 11 of the gasket 10
The protrusion 2 can be easily detached from the.

The projection 2 of the plunger 1 may have any shape as long as it has a tip 4 which is inclined in the direction of rotation at the time of joining so as to fit into the inner bottom surface 11 of the gasket 10. However, a triangular shape, a triangular pyramid, or a conical shape is preferable from the viewpoint of easy manufacturing. FIG. 1 shows a perspective view of a plunger 1 of the present invention in which the protrusion 2 has a triangular shape. In addition, an example of the shape of the protrusion is shown in FIGS.
Shown in They are a side view, a front view, and a perspective view from the left, respectively.

Further, in the syringe in which the plunger 1 is rotated counterclockwise and joined to the gasket, the projection 2 is formed with an inclination such that the tip 4 thereof is upwardly leftward.

The protrusion 2 is a gasket 10 of the plunger 1.
It may be formed on any part as long as it is eccentrically provided on the tip end surface 3 in contact with, but if it is formed on the circumference as much as possible, the rotational moment (torque) can be increased,
The force of biting by the protrusion 2 becomes more effective, and the gasket and the plunger can be reliably joined.

The material of the protrusion 2 is preferably hard plastic or metal, and among them, ABS resin, polypropylene, polyethylene, polycarbonate, tungsten, aluminum or the like is used. The projection may be adhered to the tip surface 3 of the plunger, but more preferably, the projection and the plunger can be integrally molded with the same material to obtain the plunger 1 having the projection 2.

The syringe of the present invention can be used not only for general medicines,
By molding the plunger 1 using a radiation shielding substance, it is more useful as a syringe for radiopharmaceuticals.

That is, by providing the projection 3 having an inclination in the rotation direction at the time of gasket joining on the tip end surface 3 of the plunger, the plunger 1 is rotated in that direction to join the gasket 10 easily and reliably. The plunger 1 can be easily separated from the gasket 10 by rotating the plunger 1 in the opposite direction.

When the plunger 1 having a protrusion of the present invention is used in a prefilled syringe in which a radiopharmaceutical is encapsulated, the plunger 1 can be more reliably joined to the gasket provided in the prefilled syringe during drug administration, and the plunger can be injected after drug administration. Since only the syringe can be easily separated from the syringe, only the plunger not directly contaminated by radiation can be collected and reused, and an expensive radiation shielding substance can be advantageously used as the plunger material.
Since only the portion contaminated with radiation can be separated and discarded, the amount of waste can be reduced. Tungsten is preferable as the radiation shielding substance in terms of shielding ability, processability, and the like.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a plunger 1 of the present invention.
3 shows a process of joining the gasket 10 to the gasket 10 and separating the gasket 10 from the gasket 10. When the plunger 1 having the projection 2 on the tip surface 3 which is in contact with the inner bottom surface 11 of the gasket 10 is joined to the gasket 10, the projection 2 does not act during screwing of the plunger 1 (FIG. 2 (A)). .

When the plunger 1 is screwed in to some extent, the tip 4 of the protrusion 2 contacts the inner bottom surface 11 of the gasket 10 (FIG. 2 (B)).

When the plunger 1 is further screwed in,
The tip 4 of the projection 2 is pushed into the inner bottom surface 11 of the gasket 10, and the projection 2 of the plunger 1 is pressed by the inner bottom surface 11 of the gasket 10 to be integrated with the gasket 10 (FIG. 2C). In this state, the gasket 10 easily rotates in a syringe (not shown), so that the plunger 1
The gasket 10 will not be deformed even if it is excessively rotated, and the pressure force will not be generated on the screw surface of the gasket 10. That is, the male screw of the plunger 1 is prevented from being caught in the female screw of the gasket 10.

When the plunger 1 is separated from the gasket 10, the protrusion 2 that is difficult to insert into the inner bottom surface 11 of the gasket 10 comes off due to the inclination direction of the protrusion 2 and can be easily separated (FIG. 2D). . Since the gasket 10 is molded from rubber having high elasticity, the gasket 1
After the claw 2 is removed from the inner bottom surface 11 of 0, the dent formed by the protrusion 2 on the inner bottom surface 11 is restored to a flat surface.

[0026]

EXAMPLES Specific examples using the plunger according to the present invention will be described below. (Specific Example) Comparison of Conventional Plunger and Plunger of the Present Invention The joining of a conventional plunger having no protrusion and the plunger of the present invention having a protrusion with a gasket was quantitatively evaluated. Experimental method: An experiment was conducted using the plunger having the triangular protrusions shown in FIG. In order to perform the experiment under more severe conditions, a gasket was coated with raw silicon (silicon SH200 made by Toray Dow Co., Ltd .; 100,000 cst; 5% Freon solution) to make it slip better than usual. The syringe to which the raw silicone coating gasket was joined was set on the torque gauge, and the plunger was joined. Plunger 1
After gently tightening by hand to a torque of 00, 150, 200, 250, and 300 gf · cm, the maximum torque (loosening torque) required for separation was measured. When separating the plunger, first gently rotate the plunger counterclockwise, but if the gasket idles in the syringe at that time,
The plunger was carefully rotated and separated, and the maximum torque at that time was measured. Experiments were performed with 15 samples for both plungers. Measuring device: Digital torque gauge MODEL-5027 manufactured by Aiko Engineering Co., Ltd. Experimental result: Those with parenthesized values show the torque when the bite is first loosened gently and the maximum torque when the plunger is separated by loosening it all at once, in parentheses. It also indicates that the "ERR" inside the parentheses is completely bitten and cannot be separated. “───” in the table
Indicates that the gasket was spinning in the syringe and could not be tightened to the desired torque. 30
With a torque of 0 gf · cm, the gasket slipped and could not be tightened. With a conventional plunger without protrusions, when tightened with a torque of 150 gf · cm, 10 specimens out of 15 specimens bite, and when tightened with a torque of 200 gf · cm or more, all specimens bite. did. On the other hand, the plunger having the protrusion of the present invention is 250 gf · cm.
The plunger could be easily separated from the gasket without any biting even when tightened with the torque.

[0027]

According to the plunger and syringe of the present invention, the plunger and the gasket can be joined easily and reliably, and the plunger can be easily separated from the syringe after drug administration. Therefore, the risk of damaging the syringe is eliminated, and the risk of exposure of the worker when used for radiopharmaceuticals can be reduced, and unnecessary waste can be reduced. Also, expensive radiation shield material plungers can be made reusable.

Further, according to the present invention, the gasket can be used without change to the conventional shape in which a female screw is formed on the inner surface of the gasket, the syringe structure is simple, and there is no fear of failure, and the shape of the plunger. Since it is simple, it has an effect that it can be integrally molded and is easily manufactured.

[Brief description of drawings]

FIG. 1 is a plunger 1 having a protrusion according to the present invention.
It is a perspective view showing an example.

FIG. 2 is a schematic view showing a state where the plunger shown in FIG. 1 is joined to a gasket and separated from the gasket.

FIG. 3 is a side view, a front view, and a perspective view showing an example of the shape of the protrusion of the plunger of the present invention.

FIG. 4 is a side view, a front view and a perspective view showing an example of the shape of the protrusion of the plunger of the present invention.

FIG. 5 is a schematic view showing a method of joining a plunger and a gasket in a conventional syringe.

[Explanation of symbols]

 1 Plunger 2 Protrusion 3 Tip surface 4 Tip 10 Gasket 11 Inner bottom surface

Claims (10)

[Claims] 1. A plunger of an injector used by joining a gasket to a distal end portion, wherein the plunger is joined to the gasket by a male screw of the plunger and a female screw of the gasket, and is in contact with an inner bottom surface of the gasket. A plunger having at least one protrusion on a tip surface of the jar. 2. The plunger according to claim 1, wherein the protrusion is formed so as to have an inclination in a rotation direction when the gasket is joined. 3. The plunger according to claim 1, wherein the shape of the protrusion is a triangle, a triangular pyramid or a cone. 4. The plunger according to claim 1, 2 or 3, wherein the projection is provided eccentrically on the tip end surface. 5. The plunger according to claim 1, 2, 3 or 4, wherein the protrusion is provided on the circumference of the tip surface. 6. The plunger according to claim 1, 2, 3, 4 or 5, wherein the material is made of ABS resin, polypropylene, polyethylene, polycarbonate, tungsten or aluminum. 7. The plunger according to claim 1, which is made of a radiation shielding substance. 8. The plunger of claim 7, wherein the radiation shielding material is tungsten. 9. A syringe comprising the plunger according to claim 1. 10. The syringe according to claim 9, wherein the plunger is joined with the gasket by rotating in the same direction as the tip direction of the protrusion, and is separated from the gasket by rotating the plunger in the opposite direction. How to attach and detach the plunger.