JPH01158958A - Sterilization of medical utensil by radiation - Google Patents

Abstract

PURPOSE:To perform radioactive sterilization reduced in the deterioration with the elapse of time by simple operation, in sterilizing a medical utensil formed from a polymer material by irradiating the same with radioactive rays, by hermetically packing the medical utensil using an oxygen impervious material so as to form an atmothphere whose oxygen concn. is within a specific range before irradiating the same with radioactive rays. CONSTITUTION:In sterilizing a medical utensil formed from a polymer material by irradiating the same with radioactive rays, the medical utensil is hermetically packed by using an oxygen impervious material so as to form an atmosphere wherein oxygen concn. is 4-12% and subsequently irradiated with radioactive rays. An especially pref. oxygen concn. range is 5-10%. As the adaptable medical utensil, not only one entirely made of a polymer material but also one partially made of the polymer material may be used. As the oxygen impervious material for hermetically packing the medical utensil, a material obtained by laminating an aluminum foil to a synthetic resin film or sheet or applying aluminum thereto by vapor deposition is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for sterilizing medical devices. More particularly, it relates to a method for radiation sterilization of medical devices formed from polymeric materials.

[Prior Art] A radiation sterilization method has been known as one of the methods for sterilizing medical tools. In particular, in recent years, as residual ethylene oxide in gas-sterilized medical instruments has become a problem, the importance of radiation sterilization has increased, and its application to various products is being considered.

[Problems to be Solved by the Invention] By the way, when medical devices are made of polymeric materials, there is a problem that irradiation with radiation causes a decrease in strength and functionality over time, making it difficult to permit them. hindered. Therefore, in order to solve such problems, many proposals have been made and some of them have been implemented.

For example, Japanese Patent Publication No. 55-23620 discloses a method of irradiating radiation in a wet state with a saturated moisture content or higher, and Japanese Patent Publication No. 59-192373 discloses a method of irradiating in an inert gas atmosphere. Disclosed. These methods shield medical equipment from oxygen, so irradiating them with the same star radiation as in the air will certainly prevent a decline in strength and functionality. However, the resistance of bacteria attached to medical devices to radiation increases, and the D value (the dose of radiation required to kill 1/10 of the bacteria) increases, so the same level of sterilization must be guaranteed. In order to achieve this, it was necessary to increase the irradiation dose, and the reality was that sufficient effects could not be obtained.

Therefore, Japanese Patent Application Laid-Open No. 62-74364 discloses a method in which medical devices are placed in a gas-permeable bag, radiation sterilized in the air, and then sealed together with an oxygen absorber in an oxygen-impermeable packaging material. There is. According to this method, since sterilization is performed in air, there is no increase in the D value, and since oxygen is removed by an oxygen scavenger after sterilization, deterioration over time can be prevented.

However, enclosing an oxygen absorber after sterilization is not only extremely cumbersome in terms of processing, as the product cannot be sterilized in its final packaging, and if the oxygen absorber is delayed, the deterioration of the polymeric material will progress. This poses a major problem in terms of practicality.

The present invention was made to solve these problems, and it is an object of the present invention to provide a radiation sterilization method that is easy to operate and has little deterioration over time.

[Means for solving problems]

In the present invention, the above-mentioned problems have been solved by controlling the atmosphere before sterilization of medical tools so that the oxygen concentration is 4 to 12%. That is, in the present invention, when sterilizing a medical device made of a polymeric material by irradiating it with radiation, the medical device is sealed using an oxygen-impermeable material to create an atmosphere with an oxygen concentration of 4 to 12%. This is a radiation sterilization method for medical devices, which is characterized in that the method then irradiates with radiation.

In the present invention, the oxygen concentration before sterilization has an important meaning, and a particularly preferable oxygen concentration range is 5 to 10%.

[For production]

In the present invention, by setting the oxygen concentration before sterilization to 4% or more, it is possible to suppress an increase in the D value during sterilization, and sterilization at a low dose is possible.

Surprisingly, oxygen is consumed by radiation irradiation, and if the oxygen concentration before sterilization is kept below 12%,
After sterilization, the medical device can be kept in an oxygen-free or almost oxygen-free state, thereby suppressing deterioration of the medical device over time.

〔Example〕

Although the medical device to which the present invention can be applied is made of a polymeric material, it may not only be made entirely of a polymeric material, but may also be partially made of a polymeric material. Any known polymer material can be used, including polyethylene.

Polypropylene, polystyrene, polyvinyl chloride.

Ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol.

Polymethyl methacrylate polyacrylonitrile, polyester, polyamide, polycarbonate, polyurethane, cellulose, cellulose acetate, ABS resin,
AS resin, silicone rubber.

polybutadiene, polychloroprene, polyisoprene,
Examples include styrene-butadiene copolymers and natural rubber.

Further, as the oxygen-impermeable material for sealing the medical device, a synthetic resin film or sheet laminated with aluminum foil or aluminum vapor-deposited is suitable. Such materials are opaque, but for applications requiring transparency, synthetic resin films or sheets laminated with oxygen barrier resins such as ethylene-vinyl alcohol copolymers and vinylidene chloride are suitable. Further, synthetic resin sheets other than these can also be used because oxygen permeability decreases if the thickness is increased. These materials are commonly employed in the form of bags or trays to seal medical devices, although other forms are possible.

Methods of sealing with an oxygen concentration of 4 to 12% include a method of sealing in a gas atmosphere adjusted to an oxygen concentration in this range, and a method of sealing with oxygen in the above range at the same time as or after packaging the medical device under vacuum. A method of sealing by blowing in a gas having a certain concentration, a method of sealing by blowing nitrogen gas at the same time or after packaging the medical device under an appropriate reduced pressure, and obtaining the above oxygen concentration by using the oxygen contained in the residual air.
There is also a method of sealing it in air with an appropriate amount of oxygen absorber. Such methods have been conventionally used for long-term preservation of foods, and are well known to those skilled in the art. In addition, known devices can be used as they are. Further, as the gas other than oxygen contained in the gas, nitrogen, carbon dioxide, inert gas, etc. are preferable.
Nitrogen is particularly preferred from the economic point of view.

The radiation used in the present invention includes gamma rays,
X-rays, electron beams, and the like can be used, but gamma rays are most commonly used. Further, the radiation dose is preferably in the range of 1.5 to 5 degrees OMrad, and in particular, in the present invention, the D value is approximately the same as that obtained when irradiating in air, so it is 1.5 to 2 degrees OMrad. 5 Mrad
A range of is preferred.

The method of the present invention can reduce the strength deterioration of medical devices due to sterilization, so it can be preferably applied to the sterilization of various medical devices, but especially when applied to highly functional medical devices. This is preferable because deterioration is less likely to occur. Examples of such medical devices include hemodialyzers,
Examples include devices using semipermeable membranes, such as blood filters, plasma separators, and two-oxygen lungs. In particular, when the membrane is made of cellulose acetate, the D value tends to increase more easily than when radiation sterilizing ordinary polymeric materials because the membrane contains a large amount of glycerin. This is preferable because the D value is maintained at a low value.

The present invention will be explained in more detail with reference to specific examples below, but the present invention is not limited thereto.

Example 1 Approximately 100 hollow fiber membranes made of cellulose acetate containing glycerin were bundled and tied at the center with thread, and 0.1 d of bacterial solution (water suspension of Bacillus pus+1lus) was dropped into the center and air-dried. did. This is processed into aluminum laminated film (
Several samples were prepared in which the internal oxygen concentration differed each time by packaging the product with a polyethylene terephthalate/polyethylene/aluminum/polyethylene laminate film, blowing nitrogen gas into the package, and sealing the package. The obtained sample was then irradiated with gamma rays, and the D value at each oxygen concentration was measured. The results are shown in Table 1.

Table 1 As is clear from the above results, the D value is 4% when the oxygen concentration is 4%.
If it is more than sterilized in air (oxygen concentration 20.6
%), it can be seen that sterilization can be performed using a low-intensity star. On the other hand, when the oxygen concentration is lower than 4%, D
The value increases significantly, requiring higher doses of radiation to achieve the same sterilization effect.

Example 2 Using a vacuum packaging machine and an aluminum laminated film, hollow fiber type surface liquid dialyzers using cellulose acetate membranes were packaged at various oxygen concentrations and irradiated with 2.5 Mrad gamma rays. After the irradiation, the oxygen concentration inside the package was measured, and the results shown in Table 2 were obtained.

Table 2 As is clear from Table 2, if the oxygen concentration before packaging is 12% or less, the interior of the package can be made free of oxygen after radiation irradiation. Therefore, subsequent deterioration over time can be suppressed, and a decrease in strength and function can be prevented.

Example 3 A hollow fiber hemodialyzer was packaged in the same manner as in Example 2 to produce a package with an internal oxygen concentration of 5.5%. For comparison, hemodialyzers were packaged in air using a gas-permeable packaging material and were irradiated with gamma rays of 5, OMrad. Next, in accordance with the Japanese Medical Plastics Association's standard draft for artificial kidney devices, we conducted a dialysis membrane eluate test on the membranes immediately after irradiation and after storage for one month, and the membranes based on the present invention passed all items. There was, but
A sample prepared for comparison failed in terms of ΔpH. That is, in the case of the present invention, the ΔpH immediately after irradiation is 1. 3, and it was 1°3 even after storage for 1 month, but the comparative example immediately after irradiation was 1. 8, and 2.0 after storage for 1 month (reference value: 1.5 or less). The above results also demonstrate the excellent effects of the present invention.

〔Effect of the invention〕

According to the present invention, the D value in radiation sterilization can be made comparable to that of irradiation in air, so sterilization can be performed at low radiation levels. Moreover, since the inside of the package can be kept in an oxygen-free or almost oxygen-free state after sterilization, deterioration of the medical device over time can be prevented. Also,
It is also excellent in practicality because it does not require troublesome operations such as enclosing an oxygen absorber after sterilization.

im person for patent Japan Medical Subry Co., Ltd.

Claims (1)

[Claims] When sterilizing medical devices made of polymeric materials by irradiating them with radiation, the medical devices are sealed using an oxygen-impermeable material in an atmosphere with an oxygen concentration of 4 to 12%, and then irradiated with radiation. A radiation sterilization method for medical tools, characterized by: