News about GMP/cGMP


FDA: Revised Guideline on OOS Results

FDA: Revised Guideline on OOS Results

The US FDA has revised its 16-year-old guidance on how to investigate out-of-specification (OOS) test results in laboratories. The document includes all necessary steps to be taken when investigating OOS test results. It also considers the responsibilities of the analyst and the laboratory supervisor in case of OOS results being identified, along with additional testing steps and a final evaluation of all results.

The term OOS results according to the FDA includes all test results that fall outside the specifications or acceptance criteria established in drug applications, drug master files (DMFs), official compendia, or by the manufacturer. The term also applies to all in-process laboratory tests that are outside of established specifications. The 17-page guideline follows a clear step-by-step approach in close linkage with 21 CFR 211 on

  • Identifying and Assessing OOS Test Results — Phase I: Laboratory Investigation
  • Investigating OOS Test Results — Phase II: Full-scale OOS Investigation
  • Concluding the Investigation


FDA: Investigating OOS Test Results for Pharmaceutical Production