USP <71> - Sterility Tests

What it says

General Chapter <71> describes the methodology for sterility testing of pharmaceutical articles, including membrane filtration and direct inoculation methods, incubation conditions, and the interpretation of results, used to support the sterility claim of a finished product batch.

Paraphrased for plain-language clarity. Always verify against the current published regulation text.

What it means in practice

• Sterility testing samples a small fraction of a batch and, by its statistical nature, can never provide absolute proof the entire batch is sterile - it is one piece of evidence within a broader sterility assurance strategy that includes process validation and environmental monitoring.
• Method suitability testing, confirming the test method itself works correctly for the specific product being tested, is a required precondition before sterility test results for that product can be considered valid.
• A sterility test failure carries significant weight and requires thorough investigation before being attributed to laboratory error, consistent with the same root cause standard applied to any other OOS result.

What inspectors look for

• Whether method suitability testing was performed and passed for the specific product and test method combination before routine sterility testing began.
• Whether a sterility test failure investigation follows appropriate root cause rigor, rather than defaulting quickly to a laboratory error conclusion.
• Whether sterility testing is understood and positioned correctly within the broader sterility assurance programme, rather than being treated as the sole basis for a sterility claim.

Related regulations