Validation Protocol hot and cold spot

Dear all

I’m seeking advice.
During a qualification protocol, several probes are used in different parts of the equipment (freezer for example) and, at the end of the exercise (24 hours for example), is possible to review the protocol.
What would you consider as hot/cold spot, the probe which has recorded the max temperature or the probe which has recorded the max average temperature ( which may be different than the max value)?
Thank you

The probe which has max temperature will also have max average temperature. And the place where this probe was located will consider ad hot spot, same will happen with cold spot.

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Thank you for your reply.
Unfortunately, this is not always true. I reviewed some validation exercises where the max temp and the average had different locations. In this situation, what location will be considered the worst case? and why?
Thank you

If you have different locations for max avg temperature and the max temperature, it is most probable that the max temperature was due to an excursion or spike (uncontrolled variation) that needs to be investigated. Any temperature excursions must be rigorously investigated.

Generally, you would consider the highest avg temperater a hot spot; however, spots demonstrated to have incursions or spikes could also be considered hot spots due to that variability and the risks that those incursions represent to the quality of the product. This means that you could have multiple hot/cold spots.

You can also make use of the mean kinetic temperature (MKT) calculation to weigh in the impact of temperature incursions in each location. This MKT is usually a requirement for controlled environments, for example: USP <659> states that for controlled environments (20°C to 25°C), the MKT must not be lower than 25°C.

I hope this is useful.

Reference:- WHO Guidelines on Temperature mapping of
storage areas, Technical supplement to WHO Technical Report Series, No. 961, 2011
Annex 9: Model guidance for the storage and transport of time and temperature–sensitive pharmaceutical products (TTSPP), January 2014

Summary-
A cold spot refers to the lowest temperature value(s) recorded in the space over the study
period, but with these lowest temperature value(s) remaining within the specified
temperature range (e.g. cold spots identified between +15°C to +17.5°C in a room with a
specified temperature range +15°C to +25°C).
A hot spot refers to the highest temperature value(s) recorded in the studied area over the
study period, but with these highest temperature value(s) remaining within the specified
temperature range (e.g. hot spots identified between +23°C to +25°C in a room with a
specified temperature range +15°C to +25°C).

The purpose of determining hot and cold spots is to identify the locations where the
monitoring system sensors should preferentially be located. Hot and cold spots need to be
determined seasonally as they may be significantly different in summer and in winter.
Mean temperatures
Either arithmetic mean temperatures or mean kinetic temperatures (MKT)13 can be
applied to each of the separate areas being monitored over the study period. These mean
temperature measurements can be useful in storage areas where the temperature
fluctuates with time in a repetitive pattern (e.g. sinusoidal fluctuation, periodic peak
occurrence…) and where the temperature also varies depending upon the data logger
location.
The use of mean or MKT temperatures enables the analyst to determine a mean
temperature for a given EDLM location over the study period. These figures can then be
compared between all the EDLM locations within the space. This enables the analyst to
identify the locations where the mean temperatures are consistently lower or higher, an
exercise that cannot be achieved simply by comparing individual data points.
EDLM - Electronic Data Logging Monitor

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Thank you for your reply.

According to your experience, would you consider a hot spot the highest temperature recorded during an exercise of 7 days for example, or the highest average temperature recorded during the 7 days?
I was reviewing a protocol, and there weren’t important differences or spikes, but one location had a highest average temperature than another point where was recorded the highest temperature during the exercise (but not the temperature average).
I was thinking that the permanent probe should be located where the highest average temperature was recorded ( because is the location where the mean temperature is consistently higher). Do you agree with me? How did you manage this kind of problem?

Kind regards

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Thanks for your response to my explanation.
Logically, Yes. I will consider the highest average temperature where the permanent probe should be located. Because that consistently shows higher temperatures throughout the study and hence will reflect the same trend throughout the season. Just getting the highest temperature at the one-time point may not really reflect the trend of higher temperatures. That may be an excursion in temperature which should be investigated to find out what is the root cause.

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