Humidity Excursion in Stability Unit

Hello! I was performing a re-qualification on a stability unit ( Temp-25 +/- 2C, Humidity 60% +/- 5%) and experienced a few humidity excursions. There were three different locations that exceeded specified parameters the values were: 68.5, 78.3 and 74.5% and each lasted only 15 minutes. They occurred in the middle of the night sporadically and can’t be attributed to opening the door.

I have been told in the past it was defended based on using the average humidity however, I was unsure if there were specific guidelines for humidity excursions that I could read.

Thank you in advance!

USP <1079> discusses excursions, although it’s not exactly what you were asking about the same thought process should apply. Essentially any excursion should take into account the product(s) that are stored in the units and be supported by sound scientific/technical justification.

Humidity shouldn’t fluctuate that much in an undisturbed chamber and it’s unlikely to recover 13% in 15 minutes; however that will depend on the size of the chamber. I would try to determine if there was something wrong with the data logger collecting the humidity data before going too far with this.

Good luck!

‘Forced degradation’ should have implied the role of humidity (water) in the role of the increase in concentration of the impurities (related substances) and decrease in the API assay. This should be part of risk assessment or investigation.

Strange that humidity changes so suddenly. Did you look at temperature in those same locations at that same time? Because humidity is relative humidity, it is temperature dependant. I wonder if there was a temperature fluctuation at this same time - this might help you determine the cause of the RH change.

Hi amber, if during re-qualification you find such variations in humidity at thee different location means your re-qualification doesn’t meet acceptance criteria; So your equipment not functioning properly. For that you need to contact equipment vendor. Variations in RH allowed only 5% . Equipment designed for that. U can also perform temperature distribution study to identify hot spot inside the equipment.
This is deviation not excursion, excursion means
differences in temperature relating to environmental factors. Your equipment is alredy designed to prevent out side environment effect and maintain inside the condition. As there is no chance of the excursion.
Hope this answer is suitable to resolve your query