JP2006272009A - Injector and method for attaching and detaching gasket to and from plunger in injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injector, which is a pre-filled syringe of medical supplies, screw-joining a gasket and a plunger to each other, and easily separating the plunger from the syringe after dosing the medicine. <P>SOLUTION: In this injector, the forward end face 3 coming into contact with the inner base of the gasket is provided with a projection 2, and the projection is formed with eccentricity to the center of the forward end face of the plunger. The projection includes the plunger 1 formed with a gradient so that the tip ascends toward the right in the case of rotating the plunger clockwise, and formed with a gradient so that the tip descends toward the left in the case of rotating the plunger counter-clockwise in joining the plunger to the gasket, and the gasket whose inner base coming into contact with the forward end face of the plunger is formed like a plane. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a syringe provided with a plunger and a gasket joined to the tip of the plunger. More specifically, the present invention has a protrusion on the tip surface in contact with the inner bottom surface of the gasket, and can be attached to and detached from the gasket. The present invention relates to a syringe provided with a plunger that can be easily performed.

  In medicine, there are many injections provided by a syringe filled with a chemical solution (hereinafter referred to as a prefilled syringe). In the joining method of the plunger and the rubber gasket in these syringes, usually, the fitting type shown in (1) of FIG. 5, the screw type shown in (2), the adhesive type shown in (3) and ( Four types of integral molding shown in 4) are often used. In FIG. 5, 20 is a plunger and 22 is a gasket.

  In the case of a radiopharmaceutical, it is preferable to separate the syringe and the plunger in order to separate the waste when the syringe is discarded after use and to reduce the amount of radioactive waste. In addition, a special plunger using a radioactive shielding material that shields radiation is expensive, and therefore, it is usually used repeatedly rather than disposable. Furthermore, it is possible to reduce the size of the transport container by making it easy to attach and detach the plunger and mounting the plunger only during use. Therefore, as a method for joining the plunger and the gasket, a screw type that can separate the plunger and the gasket is most often used (for example, see Patent Document 1).

JP-A-8-52214

  As described above, the syringe and the plunger tend to be required to be easily separated after use. However, in the syringes that are currently on the market, it is difficult to separate the plunger from the gasket even if the gasket and plunger are joined by screws, or the plunger bites into the gasket. Most of them end up. Even if a metal or plastic plunger is screwed into a gasket made of a material such as rubber or elastomer and a drug is administered, the plunger is rotated with the gasket in the syringe outer cylinder even if the plunger is rotated to remove the plunger. It often happened that they could not be separated because they co-rotated.

  In the present specification, “biting” means a state in which when the plunger and the gasket are joined, the plunger and the gasket are integrated for some reason and the plunger cannot be separated from the gasket. In addition, “biting” 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, but when the plunger is rotated to separate it. This means that the protrusion of the plunger can be easily removed from the gasket.

  Since the gasket is in direct contact with the drug inside the syringe, in the case of radiopharmaceuticals, the plunger and gasket cannot be separated after the radiopharmaceutical is administered, which means that the plunger is not contaminated by radiation when the syringe is discarded. Will also be discarded together, and radioactive waste will increase unnecessarily. In addition, if the plunger is bitten into the gasket and the plunger is forcibly removed, there is a risk that the syringe may be damaged or the exposure dose of the operator may increase.

The following (1) to (3) can be considered as causes for the plunger and the gasket to rotate together when separating the plunger.
(1) When the plunger is screwed into the gasket, a strong crimping force is generated on the distal end surface or the thread surface of the plunger due to the elasticity of the gasket.
(2) Since silicone oil is applied to the inside of the syringe outer cylinder to ensure the slidability of the gasket, the gasket is difficult to slip and fix.
(3) Improper screw shape.

  The present invention has been completed in view of the above circumstances, and is a prefilled syringe for pharmaceuticals, which can join a gasket and a plunger by a screw type, and rotate the plunger in a direction to remove the screw after drug administration. An object of the present invention is to provide a syringe capable of easily separating a plunger from a syringe.

  In order to achieve the above object, the present invention is a plunger of a syringe that is used with a gasket bonded to the tip, the plunger being bonded to the gasket by a male screw of the plunger and a female screw of the gasket, and the gasket The plunger has at least one projection on the tip surface of the plunger in contact with the inner bottom surface, and the projection is provided eccentrically with respect to the center of the tip surface of the plunger. When the plunger is rotated clockwise when it is joined, it is formed with an inclination so that its tip rises to the right, and when the plunger is rotated counterclockwise when joining the plunger to the gasket Plunger formed with an inclination so that its tip rises to the left, and inner bottom that touches the tip of the plunger There is provided a syringe which is characterized by comprising a gasket which is formed in a plane.

  Further, the present invention provides a gasket and a plan in which the plunger is joined to the gasket by rotating the plunger in the same direction as the tip direction of the protrusion and separated from the gasket by rotating the plunger in the opposite direction. Provide a method for attaching and detaching jars.

  The plunger used for this invention is demonstrated based on drawing. As shown in FIGS. 1 and 2, the plunger 1 has a male screw 5 formed at the tip thereof and is joined to a female screw 12 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 in contact with the inner bottom surface 11 of the gasket 10. The protrusion 2 is bonded or integrally molded to the plunger, but the one-piece molding simplifies the manufacturing process and is advantageous in terms of cost. A plurality of protrusions 2 may be provided.

  As described above, the internal thread 12 of the gasket 10 is formed on the inner side surface, and the inner bottom surface 11 of the gasket 10 in contact with the distal end surface 3 of the plunger 1 is formed flat. A recess corresponding to the shape of the protrusion 2 of the plunger 1 need not be formed on the inner bottom surface 11 of the gasket 10. By forming the inner bottom surface 11 into a flat surface in this way, the protrusion 2 of the plunger 1 is inserted into the inner bottom surface 11 of the gasket 10 so that the plunger 1 and the gasket 10 are securely joined.

  The protrusion 2 of the plunger 1 used in the present invention has directionality. That is, in the case of a syringe that rotates the plunger 1 clockwise when the plunger 1 is joined to the gasket 10, the protrusion 2 is formed with an inclination so that the tip 4 thereof is raised to the right. By forming in this way, when the plunger 1 is tightened clockwise, the tip 4 of the projection 2 is recessed from the inner bottom surface 11 of the gasket 10, and the tip 4 is pressed against the gasket and securely fixed. When loosened around, the tip 4 is connected to the inclined surface of the protrusion 2, so that the protrusion 2 can be easily detached from the inner bottom surface 11 of the gasket 10.

  The shape of the protrusion 2 of the plunger 1 may be any shape as long as it is formed so as to have a tip 4 with an inclination in the rotational direction at the time of joining so as to be difficult to insert into the inner bottom surface 11 of the gasket 10. From the viewpoint of ease of production, a triangle, a triangular pyramid or a cone is preferable. A perspective view of the plunger 1 of the present invention in which the shape of the protrusion 2 is a triangle is shown in FIG. Examples of the shape of the protrusion are shown in FIGS. They are a side view, a front view, and a perspective view, respectively, from the left.

  Moreover, in the syringe which rotates the plunger 1 counterclockwise and joins it with the gasket, the protrusion 2 is formed with an inclination so that the tip 4 thereof is raised to the left.

  The protrusion 2 may be formed on any part of the plunger 1 as long as it is decentered with respect to the center of the distal end surface 3 that contacts the gasket 10, but it is formed on the circumference (on the peripheral edge) as little as possible. Thus, the generation of rotational moment (torque) can be increased, the biting force 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 protrusion may be bonded to the distal end surface 3 of the plunger, but it is more preferable that the protrusion and the plunger are integrally formed of the same material.

  The syringe of the present invention is more useful as a syringe for radiopharmaceuticals by molding the plunger 1 using a radiation shielding substance as well as general drugs.

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

  When the plunger 1 having the protrusion of the present invention is used in a prefilled syringe enclosing a radiopharmaceutical in particular, it can be more reliably joined to a gasket provided in the prefilled syringe at the time of drug administration, and only the plunger is syringed after drug administration. Therefore, only the plunger that is not directly contaminated by radiation can be recovered and reused, and an expensive radiation shielding material can be advantageously used as the plunger material. Moreover, since only the part contaminated with radiation can be separated and discarded, the amount of waste can be reduced. As the radiation shielding material, tungsten is preferable in terms of shielding ability, workability, and the like.

  According to the syringe of the present invention, the plunger and the gasket can be easily and reliably joined, and the plunger can be easily separated from the syringe after drug administration. Therefore, there is no risk of breakage of the syringe, and not only can the risk of exposure of the operator when used for radiopharmaceuticals be reduced, but also unnecessary waste can be reduced. Further, the plunger made of an expensive radiation shielding material can be made reusable.

  In addition, the present invention can use the plunger without changing to the conventional shape in which the internal thread of the gasket is formed on the inner surface of the gasket. Since the shape is simple, integral molding is possible and the plunger can be easily manufactured.

FIG. 2 shows a process consisting of the following (1) to (4) until the plunger 1 of the present invention is joined to the gasket 10 and separated from the gasket 10.
(1) When the plunger 1 having the protrusion 2 on the tip surface 3 in contact with the inner bottom surface 11 of the gasket 10 is joined to the gasket 10, the protrusion 2 has no effect during the screwing of the plunger 1 (FIG. 2 ( A)).
(2) When the plunger 1 is screwed to some extent, the tip 4 of the protrusion 2 comes into contact with the inner bottom surface 11 of the gasket 10 (FIG. 2B).
(3) When the plunger 1 is further screwed in, the tip 4 of the projection 2 is inserted 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. 2 (C)). In this state, since the gasket 10 easily rotates in a syringe (not shown), the gasket 10 does not deform even if the plunger 1 is excessively rotated, and a pressure-bonding force is generated on the thread surface of the gasket 10. I don't have to. That is, the male screw 5 of the plunger 1 is prevented from biting into the female screw 12 of the gasket 10.
(4) When the plunger 1 is separated from the gasket 10, the protrusion 2 that is difficult to get into the inner bottom surface 11 of the gasket 10 comes off due to the directionality of the protrusion 2 and can be easily separated (FIG. 2D). . Since the gasket 10 is formed from rubber having high elasticity, after the claw 2 is removed from the inner bottom surface 11 of the gasket 10, the dent due to the projection 2 on the inner bottom surface 11 is restored to a flat surface.

  Hereinafter, specific examples using the plunger according to the present invention will be described.

(Specific Example): Comparison between Conventional Plunger and Plunger of the Present Invention The quantitative evaluation of the joining of the plunger without the conventional projection and the gasket of the plunger with the projection of the present invention was performed.
Experimental method: An experiment was performed using a plunger having a triangular protrusion shown in FIG. In order to conduct the experiment under more severe conditions, raw silicon (silicon SH200 manufactured by Toray Dow Co., Ltd .; 100,000 cst; 5% Freon solution) was applied to the gasket to improve the slip. The syringe bonded with the raw silicone-coated gasket was set on the torque gauge, and the plunger was bonded. The plunger was gently tightened by hand to a torque of 100, 150, 200, 250, 300 gf · cm, and then the maximum torque (relaxation torque) required for separation was measured. When separating the plunger, first, the plunger was gently rotated counterclockwise. At that time, when the gasket was idle in the syringe, the plunger was swirled and separated, and the maximum torque at that time was measured. For both plungers, experiments were performed with 15 specimens. As a measuring instrument, a digital torque gauge (MODEL-5027) manufactured by Aiko Engineering was used. The experimental results are shown in Tables 1 and 2 below. Table 1 shows the measurement results of the tightening-relaxation torque of the plunger without protrusions, and Table 2 shows the measurement results of the tightening-relaxation torque of the plunger with protrusions.

  In Tables 1 and 2, the values with parentheses indicate the torque when the bite is first loosened and the bite is generated, and the maximum torque when the plunger is released at once and the plunger is separated. Yes. In addition, “ERR” in parentheses indicates that it is completely bitten and cannot be separated. “───” in the table indicates that the gasket was idle in the syringe and could not be tightened to the target torque. With a torque of 300 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, biting occurs in 10 of 15 samples, and when tightened with a torque of 200 gf · cm or more, biting occurs in all samples. Occurred. On the other hand, in the plunger having the protrusion of the present invention, even when tightened with a torque of 250 gf · cm, no biting occurred, and the plunger could be easily separated from the gasket.

It is a perspective view which shows an example of the plunger which has a processus | protrusion concerning this invention. It is the schematic which shows the state which joined the plunger shown in FIG. 1 to a gasket, and isolate | separates it from a gasket. It is the side view, front view, and perspective view which show the example of the shape of the protrusion of the plunger of this invention. It is the side view, front view, and perspective view which show the example of the shape of the protrusion of the plunger of this invention. It is the schematic which shows the joining method of the plunger and gasket in the conventional syringe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plunger 2 Protrusion 3 Tip surface 4 Tip 5 Male screw 10 Gasket 11 Inner bottom surface 12 Female screw

Claims (7)

A plunger of a syringe used by joining a gasket to a tip, the plunger being joined to the gasket by a male screw of the plunger and a female screw of the gasket, and on the tip surface of the plunger in contact with the inner bottom surface of the gasket At least one protrusion, and the protrusion is provided eccentrically with respect to the center of the distal end surface of the plunger, and the protrusion rotates the plunger clockwise when joining the plunger to the gasket. When rotating, the tip is inclined so that it rises to the right, and when the plunger is rotated counterclockwise when the plunger is joined to the gasket, the tip is inclined so that it rises to the left. A plunger formed with
A syringe comprising: a gasket having an inner bottom surface that is in contact with the distal end surface of the plunger and having a flat surface.   The syringe according to claim 1, wherein the shape of the projection of the plunger is any one of a triangle, a triangular pyramid, and a cone.   The syringe according to claim 1 or 2, wherein the protrusion is provided on a peripheral portion of a distal end surface of the plunger.   The syringe according to any one of claims 1 to 3, wherein a material of the plunger is any one of ABS resin, polypropylene, polyethylene, polycarbonate, tungsten, and aluminum.   The syringe according to any one of claims 1 to 4, wherein the plunger is made of a radiation shielding material.   The syringe according to claim 5, wherein the radiation shielding material is tungsten. The syringe according to any one of claims 1 to 6, wherein the plunger is joined to the gasket by rotating in the same direction as the tip direction of the protrusion, and separated from the gasket by rotating the plunger in the opposite direction. A method for attaching and detaching a gasket and a plunger in a syringe, characterized by comprising:

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