Hydrogen Peroxide Space Disinfection Technology (I)

The commonly used cleaning and disinfection methods of clean rooms include: spraying, wiping, dragging and fumigation, etc., and the use of the first three methods may not be effective for disinfection in hard-to-reach places or possible sanitary dead spots. The use of fumigation can reduce microbial contamination.

Currently commonly used gas disinfection technologies include: formaldehyde, ozone, ethylene oxide, hydrogen peroxide, chlorine dioxide, peracetic acid and so on. Domestic commonly used is formaldehyde, ozone, formaldehyde is a highly efficient disinfectant, the early clean room using formaldehyde fumigation, can effectively kill microorganisms, including spores. As we know, formaldehyde is not friendly to the human body, and at the same time, there will be white particles remaining on the surface of the object after formaldehyde fumigation, and the killing effect of ozone on spores is not ideal, and the main push is hydrogen peroxide.

01 Necessity of disinfection of clean environment space

Is it necessary to use hydrogen peroxide or other disinfectants to clean the environment? First of all, let's look at what the statute says.

Chinese GMP Appendix 1 Sterile drugs Chapter 9 Disinfection Article 45. When necessary, fumigation can be used to reduce microbial contamination in sanitary dead spots in clean areas, and the residual level of fumigants should be verified.

WHO TRS 961 Annex6 < WHO good manufacturing practices for sterile pharmaceutical products >3.4 Fumigation of clean areas may be useful for reducing microbial contamination in inaccessible places. 

The exposure draft prior to the official version of EU GMP Annex 1 is mentioned in the exposure draft“Fumigation or vapour disinfection (e.g. Vapour-phased Hydrogen Peroxide) of cleanrooms and associated surfaces may be useful for reducing microbial contamination in inaccessible places. However, this article was deleted in the official version, so this article is good to see and understand, and does not do regulatory requirements. In clean environment disinfection technology, spraying, wiping, dragging and fumigation are usually used, and for dead corners that may exist, such as small gaps, the use of the previous three methods may not be effective disinfection, so fumigation is usually used to reduce microbial pollution in sanitary dead corners.

02 "Sterilization" or "Sterilize"?

When hydrogen peroxide is used for space treatment, it is called "disinfection", "sterilization", "purification" or "decontamination", etc., so which word is more accurate and appropriate to use?

Let's take a look at some of these words how do regulations, guidelines, etc. define sterilization.

There is no definition of these terms in Chinese GMP 2010 edition and GMP Appendix 1. The second edition of Chinese GMP Guidelines defines "sterilization" as a process or process in which live microorganisms are killed or removed from articles by appropriate physical or chemical means.

EMA《Guideline on the sterilisation of the medicinal product, active substance, excipient and primary container》: A suitably designed, validated and controlled process that inactivates or removes viable micro- organisms in a product until sterility is obtained. 

Sterilization

Chinese GMP and Appendix 1 do not give a clear definition, the first version of GMP implementation Guide "sterile drugs" gives the definition: refers to the use of chemical agents or physical methods to kill disease-causing microorganisms process.

EU GMP Appendix I Disinfection -The process by which the reduction of the number of microorganisms is achieved by the irreversible action of a product on their structure or metabolism, to a level deemed to be appropriate for a defined purpose.

Purification & decontamination

Neither Chinese GMP nor Appendix 1 gives a clear definition.

EU GMP Appendix I Decontamination-The overall process of removal or reduction of any contaminants (chemical, waste, residue or microorganisms) from an area, object, or person. The method of decontamination used (e.g. cleaning, disinfection, sterilisation) should be chosen and validated to achieve a level of cleanliness appropriate to the intended use of the item decontaminated. See also Bio-decontamination.

Annex 1 of EU GMP uses the term "Decontamination", which means "purification and decontamination".

According to relevant research data and actual use experience, it is found that when hydrogen peroxide is used, it is difficult to penetrate into the interior of the item, and hydrogen peroxide is usually used to treat the surface of the item. Due to the fragility of hydrogen peroxide treatment process, it is also easy to lead to treatment failure.

Take a look at what regulations, guidelines, and pharmacopoeia say about whether VHP is “Sterilization” or “Sterilize”

Chinese GMP Guidelines Second Edition 17.2.4 Disinfection/decontamination in Barrier Systems

"Vaporized hydrogen peroxide decontamination (bio-decontamination, which is different from wet heat and dry heat sterilization) is the main means of decontamination in the industry for sterile production isolators, factory buildings and other environments. The goal of decontamination inside the isolator is generally the drop of surface microorganisms > 6 pairs.

Chinese Pharmacopoeia 2020

1421 Sterilization Steam phase sterilization

This method refers to the method of killing microorganisms by means of a bactericidal agent distributed in the air. Commonly used sterilizers include hydrogen peroxide, peracetic acid and so on. Vapor phase sterilization is suitable for internal surface sterilization in confined Spaces.

207 Guidelines for biological indicators for sterilization

Hydrogen peroxide (VHP) vapor phase sterilization

VHP has been shown to be an effective surface sterilizer or disinfectant. Biological indicators can be used to verify the effect of surface sterilization, generally requiring a decline of 3 to 6 lg values in the number of spores.

EU GMP Annex 1

4.36 Where fumigation or vapour disinfection (e.g. Vapour-phase Hydrogen Peroxide) of cleanrooms and associated surfaces are used, the effectiveness of any fumigation agent and dispersion system should be understood and validated.

10.8 Any process (c.g. Vaporized Hydrogen Peroxide, Ultra Violet) used to decontaminate the external surfaces of sterility samples prior to testing should not negatively impact the sensitivity of the test method or the reliability of the sample.

PDA TR 70 Fundamentals of Cleaning and Disinfection Programs for Aseptic Manufacturing Facilities

Vapor Phase Hydrogen Peroxide（VPHP）

A disinfection system in which 35% hydrogen peroxide is changed to a vapor phase and used for bioburden reduction of a chamber or items in a chamber.

Decontamination of isolators uses a chemical decontamination agent, for example, hydrogen peroxide.

USP 1229.11 VAPOR PHASE STERILIZATION

Sterilization can be accomplished using sporicidal agents suspended in air (i.e., vapor). Sterilizing agents that operate in this fashion include hydrogen peroxide (H₂O₂ ), peracetic acid (CH₃CO₃CH), formaldehyde (CH₂O), and glutaraldehyde [CH₂ (CH₂CHO)₂ ] in aqueous solution. At room temperature these are liquids or solids that can be vaporized for introduction into a vessel or chamber.

PDA TR70 Fundamentals of Cleaning and Disinfection Programs for Aseptic Manufacturing Facilities--Vaporized Phased Hydrogen Peroxide (VPHP)

The VPHP process of decontamination, while effective, is still considered a disinfection step rather than a sterilization process.

Through the introduction of the above regulations, guidelines and pharmacopoeia, we can see that hydrogen peroxide treatment technology is more reasonable to call "disinfection".

03 Vaporizing hydrogen peroxide disinfection principle

Liquid hydrogen peroxide has been proven to have a good bactericidal effect as early as 100 years ago, and many studies have shown that hydrogen peroxide at a certain concentration has a killing effect on bacteria, fungi, viruses and spores, such as 3% hydrogen peroxide used in hospital disinfection. Bactericidal mechanism: first, damage the outer structure of the microorganism, so that the permeability of the protective layer is changed, which causes the change of osmotic pressure, destroys the internal and external balance, resulting in the death of microorganisms; The second is to destroy the proteins and nucleic acids in the microbial body so that the microbial death.

Vaporizing hydrogen peroxide disinfection usually uses a 35% hydrogen peroxide solution, which is transformed into a vapor body and introduced into the space by a higher temperature. In fact, the temperature of the surrounding environment is lower than the temperature when the hydrogen peroxide vapor body is just ejected, and some water vapor will condensate with the hydrogen peroxide vapor body, so the hydrogen peroxide in the environment is not a single phase, but a mixture of the gas phase and the liquid phase. When the mixed hydrogen peroxide comes into contact with the surface of the object, a micro-condensing film of the micron level is formed, and it is precisely because of the production of this micro-condensing film that the surface of the study will produce a high level of disinfection. The vaporization temperature of hydrogen peroxide is about 108℃, and 130℃ is usually used for flash technology, which can not only ensure the rapid vaporization of hydrogen peroxide solution, but also ensure that hydrogen peroxide will not be decomposed and lose the disinfection effect. We know that the boiling point of water is 100℃, and the boiling point of hydrogen peroxide is 150℃. When condensation occurs, the concentration of hydrogen peroxide in the liquid phase will increase after condensation. Under the joint action of high concentration of hydrogen peroxide and strong oxidation components such as hydroxyl free radicals generated by complex chemical action of hydrogen peroxide, it has a high level of disinfection.