What are the commonly used sterilization methods for medical packaging?

radiation sterilization

This method refers to a method in which sterilized articles are placed in gamma rays radiated by suitable radioactive sources or electron beams generated by suitable electron accelerators for ionizing radiation to kill microorganisms. The most commonly used method of this method is 60Co-γ-ray radiation sterilization. Medical devices, containers, production aids, APIs and finished products that are not damaged by radiation can all be sterilized by this method.

The SAL of products sterilized by radiation sterilization should be <10-6. The parameters controlled by gamma radiation sterilization are mainly radiation dose (referring to the absorbed dose of sterilized articles). The formulation of the dose should take into account the adaptability of the sterilized articles and the maximum number of microorganisms that may contaminate and the strongest radiation resistance. It should be verified in advance that the dose used does not affect the safety, effectiveness and stability of the sterilized articles. The commonly used radiation sterilization absorbed dose is 25KGy. Final products, APIs, and certain medical devices should be sterilized with low radiation doses as much as possible. Before sterilization, the amount of microbial contamination and radiation resistance of the sterilized item should be determined to evaluate the level of sterility assurance that the sterilization process imparts to the sterilized item.

During sterilization, appropriate chemical or physical methods should be used to monitor the radiation dose absorbed by the sterilized article to fully demonstrate that the absorbed dose of the sterilized article is within specified limits. If a radioactive dosimeter that is irradiated together with the sterilized article is used, the dosimeter should be placed in a specified location. The dosimeter should be calibrated with a standard source at initial installation and recalibrated periodically.

dry heat sterilization

This method refers to the method of placing articles in dry heat sterilizers, tunnel sterilizers and other equipment, and using dry hot air to kill microorganisms or eliminate pyrogen substances. It is suitable for sterilization of articles that are resistant to high temperature but not suitable for sterilization by moist heat sterilization, such as glassware, metal containers, fiber products, solid reagents, liquid paraffin, etc., which can be sterilized by this method.

Dry heat sterilization conditions are generally 160~170℃*120min or more, 170~180℃*60min or more or 250℃*45min or more, other temperature and time parameters can also be used. SAL < 10-6 after sterilization should be guaranteed. The SAL of the article after dry heat overkill should be < 10-12, and the article generally does not need to be tested for contaminating microorganisms before sterilization. Dry heat sterilization at 250℃*45min can also remove pyrogenic substances in aseptic product packaging containers and related production and filling utensils.

When dry heat sterilization is used, the items to be sterilized should have an appropriate loading method and should not be arranged too densely to ensure the effectiveness and uniformity of sterilization.

Dry heat sterilization should confirm that the temperature distribution in the sterilizer meets the set standards and determine the location of the coldest spot. A commonly used biological indicator is Bacillus subtilis spores (Spores of Bacillus subtilis). The bacterial endotoxin inactivation verification test is a test to demonstrate the effectiveness of the depyrogenation process. Generally, less than 1000 units of bacterial endotoxin is added to the item to be depyrogenated, and it is proved that the depyrogenation process can reduce the endotoxin by at least 3 logarithmic units. The bacterial endotoxin used in the bacterial endotoxin inactivation verification test is generally Escherichia coli endotoxin.

moist heat sterilization

This method refers to the method of placing articles in a pressure steam sterilizer and using high-pressure saturated steam, superheated water spray and other means to denature the proteins and nucleic acids in the microbial cells to kill microorganisms. This method has strong sterilization ability and is the most effective and widely used sterilization method in thermal sterilization. Medicines, containers, culture medium, sterile coats, rubber stoppers and other items that do not change or be damaged when exposed to high temperature and humidity can all be sterilized by this method. Circulating steam cannot completely kill bacterial spores, and can generally be used as an auxiliary sterilization method for heat-labile sterile products.

The moist heat sterilization conditions usually adopt the procedure of 121℃*15min, 121℃*30min, or 116℃*40min, and other temperature and time parameters can also be used, but the SAL<10-6 of the sterilized items must be guaranteed. For thermally stable items, the overkill method can be used, and the SAL should be < 10-12. The standard sterilization time F0 for products with poor thermal stability [refers to the standard sterilization time when the sterilization temperature is 121 °C, the heat resistance parameter D value of the biological indicator bacteria is 1 point, and the sterilization temperature coefficient Z value is 10.0 °C ( The microbial equivalent inactivation rate calculated at 121℃)] is generally not less than 8min. If the thermal stability of the product is very poor, the F0 of moist heat sterilization can be allowed to be lower than 8. In this case, the contaminated microorganisms in the product should be strictly monitored during the entire production process, and various measures should be taken to reduce microbial contamination. level to ensure that the sterilized products meet the sterility assurance requirements.

When moist heat sterilization is used, the sterilized items must be properly loaded and cannot be arranged too densely to ensure the effectiveness and uniformity of sterilization.

Moist heat sterilization should identify cold spots that may exist in the sterilizer at different loads. When biological indicators are used to further confirm sterilization, they should be placed in a cold spot. The biological indicator of this method is Bacillus stearothermophilus spores.

Ethylene oxide sterilization

Ethylene oxide, also known as ethylene oxide, is a colorless liquid at low temperature with an aromatic ether smell, a boiling point of 10.8 °C, an odor threshold of 760 mg/m to 1064 mg/m, and a density of 1.52; ethylene oxide is flammable and easy to Explosion, its minimum combustion concentration is 3%. Ethylene oxide gas has strong penetrating power.

Ethylene oxide gas has strong bactericidal power and wide bactericidal spectrum, and can kill various microorganisms including bacterial spores. Ethylene oxide does not damage sterilized items and has strong penetrating power, so most items that are not suitable for sterilization by general methods can be sterilized and sterilized with ethylene oxide. For example, electronic instruments, optical instruments, medical instruments, books, documents, fur, cotton, chemical fibers, plastic products, wood products, ceramics and metal products, endoscopes, dialyzers and disposable medical supplies, etc. Ethylene oxide is currently one of the most important low-temperature sterilization methods.

Ozone sterilization

Ozone is a strong oxidant, and the sterilization process is a biochemical oxidation reaction. O3 sterilization has the following 3 forms:

Ozone can oxidize the enzymes needed to decompose the glucose inside the bacteria, so that the bacteria are inactivated and killed.

Directly interact with bacteria and viruses, destroy their organelles and DNA, RNA, destroy the metabolism of bacteria, and cause bacterial death.

It penetrates through the cell membrane tissue, invades the cell, acts on the lipoprotein of the outer membrane and the lipopolysaccharide inside, causing the bacteria to undergo permeability distortion and dissolve and die

The speed and effect of ozone sterilization is unparalleled. Its high redox potential determines its wide application in oxidation, decolorization and deodorization. Some studies have pointed out that ozone dissolved in water can kill almost all substances in water that are harmful to human body. , such as iron, manganese, chromium, sulfate, phenol, benzene, oxides, etc., and can also decompose organic matter and kill algae.

Compared with conventional sterilization methods, ozone disinfection and sterilization methods have the following characteristics:

(1) Efficiency. Ozone disinfection and sterilization is based on air as coal, and does not require any other auxiliary materials and additives. It has good body tolerance, complete sterilization, and also has a strong function of removing mildew, fishy, ​​odor and other odors.

(2) High cleanliness. The rapid decomposition of ozone into oxygen is the unique advantage of ozone as a disinfection and sterilization. Ozone is produced by the use of oxygen in the air. During the disinfection process, the excess oxygen is combined into oxygen molecules after 30 minutes, and there is no residue, which solves the problem of secondary pollution caused by the disinfection method of disinfectants, and eliminates the need for Clean again after disinfection.

(3) Convenience. Ozone sterilizers are generally installed in clean rooms or air purification systems or sterilization rooms (such as ozone sterilizers, transfer windows, etc.). According to the sterilization concentration and time of debugging and verification, set the sterilizer's opening and running time according to time, which is easy to operate and use.

(4) Economical. By comparing the use and operation of ozone disinfection and sterilization in many pharmaceutical industries and medical and health units, the ozone disinfection method has great economic and social benefits compared with other methods. In today's rapid industrial development, environmental protection issues are particularly important, and ozone disinfection avoids secondary pollution caused by other disinfection methods.

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