Sterile Filtration
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
The removal of microorganisms from a liquid or gas by passage through a validated sterilizing-grade filter, most commonly nominally rated 0.22 µm, used as the sterilization step for heat-labile drug products, or in combination with terminal sterilization or aseptic processing for solutions, buffers, and gases in aseptic manufacture.
Sterile filtration does not itself confer terminal sterility assurance equivalent to a validated moist-heat cycle, so a filter-sterilized product is by definition aseptically processed and carries the associated environmental and process controls.
Filter validation by the filter manufacturer (bacterial retention challenge using Brevundimonas diminuta) establishes the pore-rating claim, but the user must additionally demonstrate that the filter is compatible with the specific product and process — chemical compatibility, extractables, and adsorption of active ingredient must all be assessed.
A sterilizing-grade filter’s claimed retention is only valid if its physical integrity is confirmed before and after use by a correlated non-destructive integrity test.
- —Typically 0.22 µm nominal pore rating for liquids; 0.1 µm used for mycoplasma-level retention.
- —Filter-sterilized product is aseptically processed, not terminally sterilized.
- —Bacterial retention validation (by the filter vendor) must be paired with a user-side compatibility assessment.
- —Physical integrity testing before and after use is required to confirm the filter performed as validated.
EU GMP Annex 1 (2022); PDA TR 26; ASTM F838
Frequently asked questions
What is Sterile Filtration?
The removal of microorganisms from a liquid or gas by passage through a validated sterilizing-grade filter, most commonly nominally rated 0.22 µm, used as the sterilization step for heat-labile drug products, or in combination with terminal sterilization or aseptic processing for solutions, buffers, and gases in aseptic manufacture.
Which regulations cover Sterile Filtration?
EU GMP Annex 1 (2022); PDA TR 26; ASTM F838