JPH06154324A - gasket - Google Patents

Abstract

(57) [Summary] [Objective] To provide a prefilled syringe incorporating a gasket having excellent airtightness or liquidtightness and also excellent in slidability. A gasket having at least one peak which is selected according to a specific inner diameter of the syringe barrel and comes into sliding contact in an airtight or liquid-tight manner with the inner wall of the syringe barrel in a compressed state, and (a) is in sliding contact with the syringe barrel. The contact area S (mm ² ) of at least one of the peaks is 28 mm ² or more, or the contact width is 0.7 mm or more, and (b) the compressibility C (%) of the peak is 1 to 5
And (c) the product of the compressibility C (%) of the peak and the contact area S (mm ² ) has a value of about 100 to about 250.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical injector, more specifically, to a so-called prefill syringe, which is already filled with a drug solution.

[0002]

2. Description of the Related Art As a conventional prefill syringe type product,
For example, as shown in FIG. 1, the syringe barrel body 1 is filled with a drug solution, the opening of the tip portion of the barrel body 1 is sealed by the elastic plug member 2 and the luer cap type holder 3, and the rear end portion is sealed by the gasket 5. It is sealed. Such prefilled syringes are known to be mainly for subcutaneous injection or for dentistry, and the needle head 4 is attached to the tip of the holder 3.
It is used by mounting.

Particularly in the field of radiopharmaceuticals, a disposable syringe pre-filled with a radiopharmaceutical does not require the operation of transferring the radiopharmaceutical solution from the vial to the syringe, so that the radiation exposure of users such as doctors and nurses is effective. It can be used around.

One example of the structure of a prefilled syringe which is commercially available and used in the art is an injection barrel made of hard glass, a liquid medicine contained therein, and a gasket made of butyl rubber. It consists of a pusher for sliding the gasket. In such a prefilled syringe, since the drug solution, which is the content solution, is administered to the human body, as a matter of course, foreign matter and bacteria should not be mixed from the external environment within a certain storage period. . Furthermore, the content liquid should not leak outside between the inner wall of the syringe barrel and the outer circumference of the gasket. Therefore, air tightness or liquid tightness of the gasket is one of the important characteristics. Regarding this point, the purpose can be achieved by making the outer diameter of the gasket larger than the inner diameter of the injection cylinder, but an excessive force is required to push down the pusher when the content liquid is administered. That is, there is a drawback that the slidability is poor. Therefore, it has been pointed out by the medical doctor that the slidability is one of the important characteristics together with the liquid tightness or the air tightness described above. In fact, the conventionally used prefilled syringes have been problematic in that they have poor slidability.

Regarding this problem, Japanese Patent Publication Sho 57-2
The 6782 specification states that the contact area S (mm ² ) of the sliding contact portion of the gasket outer diameter on the inner wall of the injection cylinder is about 350 when the product of the inner diameter of the injection cylinder and the compression rate C (%) calculated from the outer diameter of the gasket is about 350. Or about
It is disclosed that a gasket having excellent slidability and airtightness can be obtained by showing a value of 900.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a prefill syringe incorporating a gasket which is excellent in airtightness or liquidtightness and also slidability.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have studied the slidability of a prefill syringe from various viewpoints. As a result, the gasket disclosed in the present specification has been provided with a prefill conventionally provided. The inventors have found that the drawbacks of a syringe are solved, and that a prefilled syringe excellent in airtightness or liquidtightness and also in slidability is provided, and completed the present application.

A syringe according to a specific example of the present application will be described below with reference to the accompanying drawings.

[0009]

EXAMPLES The inventors have found that the contact area S (mm ² ) obtained by the following equation for the shape and slidability of the gasket and the initial resistance value have the relationship shown in FIG.

S (mm ² ) = πr (d ₁ + d ₂ + d ₃ + ... d _n ) [r is the inner diameter (mm) of the syringe barrel, and d ₁ , d ₂ , d ₃ , d _n are injections Indicates the contact width (mm) at which one peak of the cylinder and gasket are in sliding contact. ]

According to the above-mentioned Japanese Patent Publication No. 57-26782, if the product of the compressibility C (%) obtained by the following equation and the contact area S (mm ² ) is less than 350, the airtightness is obtained. Alternatively, it teaches that the liquid tightness becomes poor.

[0012] [R indicates the peak outer diameter (mm) of the gasket in sliding contact, and r indicates the inner diameter (mm) of the injection cylinder. ]

However, in the specification, d ₁ and d _n
There is no description about the magnitude relation with (for example, the magnitude relation between d ₁ and d ₂ ). According to the results of examination by the present inventors, (d ₁ + d
₂ + d ₃ + ... d _n ) That is, it was surprisingly found that the airtightness or the liquidtightness is poor even if the total contact area of the contacting peaks is sufficiently high. A specific example will be described below.

[0014]

[Table 1]

[Table 2] No. 9 shown in Table 1 (Table 1) and Table 1 (Table 2)
(D ₁ + d ₂ + d ₃ + ... d _n ) = 0.91 mm, and the total contact area S thereof is 35.6 mm ² . However, the airtightness or liquidtightness of this gasket was poor, and it was not compliant with the suction test according to the disposable syringe barrel standard.

[0015]

[Table 3] Furthermore, as a result of research into this cause, as shown in Table 2 (Table 3), the area where one peak of the gasket is in contact is d ₁ = 0.7 or less and S ₁ = 25 mm ^{2 or} less, and the suction test fails. I found that. That is, in terms of airtightness or liquid-tightness, at least 1 is more than the sum of the contact width and contact area of each peak of the gasket.
It was shown that the contact width and contact area of the double peaks are unexpectedly important factors. That is, in order to manufacture a gasket for a prefill syringe excellent in air-tightness or liquid-tightness that is suitable for a suction test due to this fact, the contact width and contact area of the gasket have at least one peak that the gasket has. At least 0.7m each
It must be at least m or at least 28 mm ² .

Next, the gasket shape and slidability will be described. A large number of syringes according to this explanation were produced, and the relationship between the product of the compressibility C (%) of the gasket and the total contact area S (mm) and the sliding value was measured, and the results shown in FIG. 3 were obtained. .

As mentioned above, Japanese Patent Publication No. Sho-57-267.
The 82 specification discloses that a gasket having excellent sliding property and airtightness can be obtained if the product of S and C shows a value of about 350 to about 900. In the present specification, when a syringe is used for medical purposes, it is sterilized with ethylenoxide gas at about 60 ° C. to about 65 ° C. for about 6 hours to about 8 hours in a state where a gasket is housed in a syringe. However, it does not disclose a prefilled syringe that is already filled with the drug solution, which has been described and which has been studied by the present inventors. The present inventors have surprisingly found that an excellent gasket can be obtained at 350 or less. As shown in Table 1, when the product of S and C was less than 100, the disposable suction test failed. That is, air tightness or liquid tightness is poor. on the other hand,
If it is about 250 or more, the slidability is poor and a large force is required to push the pusher. Therefore, the product of S and C is 100 or 250.
, Preferably a gasket having a value of about 120 to about 200 is excellent in airtightness or liquidtightness,
Moreover, it provides a prefilled syringe excellent in slidability. Furthermore, in a gasket with multiple peaks, the peak diameter at the tip is made larger than the other peak diameters, so that the remaining peaks play a role in stably holding the gasket in the syringe barrel when the gasket slides. As a result, the airtightness or the liquidtightness can be maintained. Further, the sliding property can be further improved by applying a silicone coating or silicone coating permitted by the Pharmaceutical Affairs Law to the gasket. However, it is important to note that the compression rate C (%) has its own range depending on the inner diameter of the individual injection cylinder used.
The product of the compressibility C (%) determined by the inner diameter of this syringe and the corresponding contact area S (mm ² ) is about 100 to about 25.
It means to show the value of 0. Furthermore, the compression rate C
In (%), it was found that the compressibility calculated from the diameter of each peak of the gasket is such that C is preferably 1 to 5, preferably 2 to 4.

[0018]

The gasket of the present invention is excellent in airtightness or liquid-tightness.
It is suitable for use as an injection because it is free of foreign matter and bacteria from the external environment. In addition, there is no risk of liquid leakage during administration.

Further, when used in the field of radiopharmaceuticals, the dose is administered using a shield such as lead in order to avoid unnecessary exposure. Power is useless,
Therefore, the possibility of failure such as administration error becomes extremely low.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a prefill syringe.

FIG. 2 is a characteristic diagram showing a relationship between a sliding contact value and a contact area of a gasket.

FIG. 3 is a characteristic diagram showing a relationship between a sliding contact initial value and a product of a contact area of a gasket and a compressibility.

[Explanation of symbols]

 1 injection cylinder 2 elastic stopper member 3 luer cap type holder 4 injection needle head 5 gasket 6 pusher

Claims (5)

[Claims] 1. At least one peak which is selected according to a specific inner diameter of the syringe barrel and comes into sliding contact with the inner wall of the syringe barrel in a compressed state in an airtight or liquid-tight manner. The contact area S (mm ² ) of at least one peak of the contacting gasket is 28 mm ² or more, or the contact width is 0.7 mm or more, and (b) the compressibility C (%) of the peak shows a value of 1 to 5. (C) The gasket, wherein the product of the compressibility C (%) of the peak and the contact area S (mm ² ) exhibits a value of about 100 to about 250. 2. The gasket of claim 1, wherein the syringe barrel has an inside diameter of about 12.45 mm. 3. The gasket of claim 1, wherein the syringe barrel has an inner diameter of about 8.7 mm. 4. The gasket of claim 1, wherein the gasket length has a length required to insert the pusher into the gasket and is in the range of about 8 mm to about 15 mm. 5. The gasket according to claim 1, which is used in a prefill syringe.