Dirty Hold Time tests

Beyond the evaluation of time, Which scope have to have my analitical methods of recoveries waste of active ingredient to handle the DHT tests?

I’m worried that it could be questioned the substance stability, especially in those processes in which the product can be dried on the surfaces…

Thanks for helping me

It depends on your formulation and your cleaning procedure. Usually, the ‘dirt’ becomes caked on the material of construction (normally stainless steel). Influences of your cleaning procedure are; Time, Action, Concentration, Temperature (TACT).

Are you asking about degradation by-products? So that over time the product changes to something else, and that your analytical methods must look for the by-product?

I’ve not tested for by-products during dirty hold time. If this is your question, I’ll admit that it has validity. If there are by-products, how much are you expecting? 10% degredation, or 80% degredation?

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I think the purpose of clean hold time study is to demonstrate the capability of equipment storage environment to maintain equipment cleanliness up to certain period; after completing CHT study established CHT priod is the limit to allow equipment can b keep idol, no further cleaning required between period for re-use of equipment.

DHT is totally different; Here we need to demonstrate the capabilities of cleaning method; Existing cleaning method capable to clean the certain period dirty equipment. As we know unclean equipment become more rusty and wall sticked material becomes more harder and not easy to clean. Established time period during DHT study will used to design SOP to allow the equipment in dirty condition after use.

I’m with you 100%, my question was to clarify the OP question. The original question related to “waste” and “stability” of the API - hence I wondered if his question was about testing for degredation by-products over time

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