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VHP or VH2O2 cycle development and optimization

Development and optimization of VHP cycles

The acquisition of new equipment or facilities to be decontaminated with vaporized hydrogen peroxide, especially if you are not familiar or even do not have a certain level of experience, can be a significant challenge for the laboratory personnel. Regarding the development of cycles and validation, the know-how, the identification of limitations and the level of performance attainable is absolutely essential for the future as the installation will have to be revalidated at least once a year. Since production needs evolve, new challenges arise and at that point, not having made a good cycle development and a wise validation can produce inconsistent results that may lead to deviations and put the process at risk.

The key to everything is therefore to have made a good study of the decontamination process by VHP or VH2O2 in order to understand the limits and apply the adequate safety margin to get a good performance mitigating the risks.

Netsteril offers the VHP or VH2O2 cycle development services with this in mind. The method is based on the latest technology, through Enzymatic Indicators, which allow to determine quickly and quantitatively the level of decontamination (logarithmic reduction) reached by the cycle.

Cycle development studies are carried out in two phases:

Phase I. Determination of the correlation between biological and enzymatic indicator by the fractional cycle method.

The objective of this phase is to find the correlation between the biological and the Enzymatic Indicator.

The Enzymatic Indicators (EI) act in the same way as a Biological Indicator. Just as a Biological Indicator (BI) consists of a population of spores, typically of the order of 106 units, which is suffering a loss of population as it is subjected to an oxidizing atmosphere (H2O2), the Enzymatic Indicator consists of a biomolecule that is losing its activity under the same pattern or ratio. The problem with BIs is that each one contains a relatively different spore population and, most importantly, a different resistance level (D-value). For this reason, it is not expected that each biological indicator behaves the same when subjected to the same process of peroxidation and hence, it is recommended to use up to three indicators in the same point. Whereas on the contrary, EIs offer much less variability but in order to use it in validation, it is necessary to correlate them to a BI with certain D-Value and population (as it is established at the moment in the Pharmacopoeia). Therefore, once established the correlation between one and another, we can replace the biological indicator and use the enzymatic one, which is much faster to read (no need to wait 7 days) and has the advantage that offers a gradual result, between 3 and 9 logs.

The establishment of the correlation is done by the fractional cycle technique. This technique consists of having a number of indicators of both types at a certain point that allows easy handling in order to go, sequentially and during equal fractions of the cycle, stopping the exposure process. From all the series of indicators, the first biological indicator with negative result serves to fix the RLU (Relative Light Units) equivalent to 6 logs. From there, the Enzyme Indicator can be used as an equivalent Biological Indicator for that process.

Phase II. Determination of cycle parameters according to the worst case method

In phase I we have qualified the Enzyme Indicator, which offers us the advantage of speed and quantitative measurement. Now we will have to introduce these indicators in all the points of the enclosure (chamber, isolator, room, etc.) to check that we are effectively reaching all these points. This phase is the one everybody knows, the traditional approach. Previously or in parallel chemical indicators can be used to verify that at all points there is a certain exposure to hydrogen peroxide. However, chemical indicators do not give much information. They simply react chemically with a dye and change color but it is not an analogous method to determine the logarithmic reduction level. With the Enzymatic Indicators instead, we can quickly know if with the executed cycle we are near or far from the objective or even if we are not going too far and there’s room to reduce cycle times and costs.

With these tools and using this method, Netsteril is in an ideal situation to be able to offer cycle developments not only faster, but also with greater security in terms of the reduction levels reached at all points of the validation.

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