Equipment
Pre-Use Post-Sterilization Integrity Testing
PUPSIT — the gold standard for verifying sterilizing-grade filter integrity after sterilization and before any product processing begins.
- EU GMP Annex 1 Compliant
- 21 CFR Part 11 / GAMP5
- Pharmexpert Solution
Definition
What is PUPSIT?
PUPSIT stands for Pre-Use Post-Sterilization Integrity Testing. It is the test performed on a sterilizing-grade filter after that filter has been installed and sterilized, but before any product is filtered through it. The point is narrow and important: to confirm that the filter assembly which is about to protect the product is intact at the moment it starts doing that job.
Testing before sterilization is not the same thing. Sterilization itself — and the handling, installation and assembly around it — can damage a filter or its connections. A filter that passed an integrity test yesterday, before it was steamed or irradiated, tells you nothing about its condition after that process. PUPSIT closes the window between the last test and the first drop of product.
The test covers more than the membrane. Integrity is verified across the sterilizing filter, its housing, the support structures and every connection in the assembly, because a compromised connector defeats an intact membrane just as completely as a torn filter would.
Quick reference
- What
- Verifies the integrity of the sterilizing filter, its housing, support structures and all connections.
- When
- After installation and sterilization, and prior to filtering active product.
- How
- By Bubble Point, Diffusive Flow, or Pressure Hold test methods.
- Concern
- Prevents "filter flaw masking" — flaws blocked by contaminants during filtration that would go undetected in a post-use test.
- Application
- Gamma-irradiated single-use sterilizing-grade filtration bags and tubing assemblies.
Sequence
Where the test sits is what makes it compliant
Two workflows, the same five operations. Only one of them verifies the filter after the process most likely to damage it.
Conventional (non-PUPSIT)
Step 1
Wetting
Step 2
Pre-use IT
Tested before sterilization
Step 3
Sterilize
Step 4
Filtration
Step 5
Post-use IT
PUPSIT-compliant
Step 1
Sterilize
Sterilize before testing
Step 2
Wetting
Step 3
Pre-use IT
Step 4
Filtration
Step 5
Post-use IT
Both sequences contain the same five operations. What separates them is where the pre-use integrity test sits: on the conventional rail it happens before sterilization, so nothing verifies the assembly after the process most likely to damage it. Testing after sterilization is what makes the sequence compliant.
Procedure
How PUPSIT is performed
Six steps, in order. Each one exists because skipping it produces either a false failure or an undetected flaw.
- 01
Wetting the filter
The membrane is fully wetted with the specified fluid and displaced air is vented, since an incompletely wetted membrane produces a false failure.
- 02
Integrity testing
The test is run by Bubble Point, Diffusive Flow or Pressure Hold, against limits correlated to the filter’s microbial retention validation.
- 03
Air blow dry
Where the procedure requires it, the assembly is blown dry with air before re-wetting, so the next step starts from a known condition.
- 04
Re-wet and prepare
The filter is re-wetted for processing and the initial fluid through the line is diverted to discard rather than to the batch.
- 05
Vent-filter testing
The vent filter is tested in its own right, because it is part of the sterile boundary and fails the same way the product filter does.
- 06
Post-use test
After the run, the filter is tested again to confirm it remained integral throughout the filtration it has just performed.
Regulatory requirements
What the regulators require
Both summaries below are paraphrased. Follow the links for the source text.
European Union
EU GMP Annex 1 — §8.87
Annex 1 requires that the integrity of a sterilised filter assembly is verified by testing before use, so that damage or loss of integrity caused by filter preparation, installation and sterilization is detected before product is committed. The test method must be validated, and its limits must correlate to the microbial retention validation established for that filter.
Read EudraLex Volume 4, Annex 1(opens in a new tab)United States
PDA / FDA rationale
The rationale recognised in PDA technical literature and FDA aseptic processing guidance is a risk one: testing after sterilization and before use detects a non-integral filter before any product is committed to it, avoiding both batch loss and the contamination risk that follows. It also addresses flaws that contaminants deposited during filtration could otherwise mask from a post-use test.
FDA guidance on aseptic processing(opens in a new tab)
Pharmexpert solution
Every filtration parameter, covered
The parameters a filter validation has to control — and the Pharmexpert solution's status against each.
Software
Records that survive an audit
Seven capabilities that make the data defensible, not just the test.
ER/ES Readiness
Electronic records and electronic signatures configured for 21 CFR Part 11.
User Management
Individual user IDs with role-based access to functions and records.
Recipe Creation
Validated test recipes stored and recalled, so a test runs the same way every time.
Data Storage & Management
Secure centralised storage of test data across the installation.
Time-Stamped Reports
Reports generated automatically for each run, carrying the run’s own timestamp.
Audit Trail
A complete, tamper-evident record of actions taken against the system.
Data Backup & Restoration
Routine backup with a defined restoration path for stored records.
Frequently asked
PUPSIT questions, answered
The six questions that come up in almost every PUPSIT conversation.
What is PUPSIT?
PUPSIT is Pre-Use Post-Sterilization Integrity Testing: an integrity test performed on a sterilizing-grade filter after it has been installed and sterilized, but before any active product is filtered. It verifies the sterilizing filter, its housing, support structures and all connections.
When must PUPSIT be performed?
After installation and sterilization of the filter assembly, and prior to filtering active product. Performing the pre-use test before sterilization does not satisfy the requirement, because it cannot detect damage caused by sterilization or by the handling around it.
Which test methods are used?
Bubble Point, Diffusive Flow, or Pressure Hold. The method and its limits must be validated and must correlate to the microbial retention validation established for the filter being tested.
Why do regulators mandate PUPSIT?
EU GMP Annex 1 §8.87 requires pre-use testing of the sterilised filter assembly so that damage or loss of integrity from filter preparation, installation and sterilization is detected before product is committed. Detecting a non-integral filter at that point prevents both batch loss and contamination risk.
What is filter flaw masking?
Filter flaw masking is where a flaw in the membrane becomes blocked by contaminants during filtration, so a post-use integrity test passes even though the filter was not integral while it was working. A pre-use post-sterilization test catches such a flaw before the product ever passes through.
Is the Pharmexpert solution 21 CFR Part 11 compliant?
Yes. The Pharmexpert software provides electronic records and electronic signatures, individual user IDs with role-based access, a complete tamper-evident audit trail, stored validated recipes, time-stamped reports, and backup with a defined restoration path.