Recently a question about the re-use of sterilizing grade filters came up again. The question, can it be done and what are the regulators thinking about it ? Well, it certainly depends on the application, in very few application sterilizing grade filters are re-used. These are for examples large volume parenterals, which are terminally sterilized after filtration, API, which often do not claim sterility, and in instances blow-fill-seal application, which though are multi-batch applications, not necessarily multi-use. In any case, running costs are driven down by the re-use of a $200 filter, but is it really worthwhile ? This certainly will need to be answered by the filter end-user.
Personally, I hope I will not receive an injection of a drug product which run through a re-used sterilizing grade filter. Why? Because, not only do I not kow how much the performance might have been influenced by multiple steam sterilizations, cleaning cycles, possible pressure pulsations etc., but has all previous filtration residue and debris been removed ? Is that cleaning cycle validated and how thorough is it ? Has the polymeric structure been compromised and sheds particulates ? Are the support fleeces lost its stabilizers and become brittle ?
A multitude of questions, which require answers because one wants to re-use a sterilizing grade filter, one better does understand the possible consequences. Again, is all the validation work worthwhile, the supposedly savings ?
Now are sterilizing grade filter designed to withstand multiple uses. Yes, current filter designs can cope with a lot of stresses, but one should not believe that these are withstanding any abuse. Manufacturers put processing or operating limits on their filters for reasons. These need to be observed !
Again, sterilizing grade filters can be, for very specific applications, re-used. In the majority of applications, though, don't !
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