Missing OOS Trending leads to FDA Warning Letter

Recommendation
13-15 May 2025
Vienna, Austria
Practical Approaches for USP General Chapter <1058> Compliance in the QC Laboratory
This FDA Warning Letter issued to the Indian pharmaceutical manufacturer Mylan Laboratories Ltd. on April 3rd, 2017 is based on an FDA inspection that took place in September 2016. The FDA's complaints were as follows:
In the first six months of 2016, Mylan Laboratories invalidated 101 of 139 of its initial OOS assay results (approx. 72%) without sufficient root cause analysis for those OOS results. As an example, the six-month assay result in a stability test was mentioned. The original, failing result was invalidated without appropriate investigation and replaced by fitting results from the re-testing.
In the failure investigation, "analytical bias" was given as a reason for the deviating results. However, no Investigation was instigated to determine how this obviously significant error in the analyses could be eliminated in the future.
Now, a trend analysis of all OOS results is expected of Mylan Laboratories, regardless whether they are confirmed or initial OOS results. Mylan Laboratories has to provide the FDA with the following details for every OOS result:
- name of the tested product,
- date of analysis,
- type of analysis,
- purpose of the test,
- initial result,
- retest result,
- unconfirmed assignable root cause for the OOS result.
Furthermore, the company's SOP for the handling of OOS results must be revised. In the future, it has to be ensured by the SOP that all OOS results are included in the trending.
For more details please see the complete Mylan Laboratories Ltd. FDA Warning Letter.
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