FDA Warning Letter: Averaging Data to Override OOS Findings

The U.S. Food and Drug Administration (FDA) has published a Warning Letter dated 23 July 2026 to a veterinary drug manufacturer in Nebraska, following an inspection in January 2026.

The letter identifies three areas of significant CGMP violations: OOS investigations, incoming component testing, and process validation.

OOS Investigations

At the centre of the Warning Letter is the firm's repeated failure to adequately investigate OOS results before releasing batches.

In one case, finished product testing returned a confirmed OOS result. The firm performed internal retesting on three individual bottles, two of which also failed the specification. The FDA states: "Rather than invalidating the OOS result through a scientifically justified investigation, your firm [averaged] the three results […] and released the batch for distribution."

In a second case, an in-process OOS was identified, the required corrective adjustment specified in the approved Master Production Record was not performed, and the contract laboratory subsequently confirmed the finished product as OOS. The batch was released nonetheless.

Another finding mentioned in the Warning Letter refers to the process validation of a tablet product where 17 in-process samples exceeded the USP assay specification. Instead of investigating the root cause, the firm manually crossed out the original upper specification limit in the batch record and handwrote a higher value without any documented justification.

FDA's response to the firm's corrective action commitments was critical: while procedural revisions were acknowledged, the agency found the response inadequate for failing to address the safety of already distributed products and providing no retrospective risk assessment.

Incoming Component Testing

FDA found that a raw material beyond its retest date was used in manufacturing. On the same day both affected batches were released, the contract laboratory confirmed that the material had failed retesting. The authority writes: "Your decision was based on a qualitative comparison of the Fourier-transform infrared (FT-IR) spectroscopy scan for OOS raw material and a previous scan spectrum of itself, that determined the material passed specification."

FDA also noted that identity testing for high-risk components was either incomplete or entirely absent, meaning the firm lacked adequate assurance of component suitability prior to use in manufacturing.

Process Validation

The firm's Quality Manager confirmed to FDA investigators that no validation protocols or final validation reports are written. A review of a tablet validation batch record revealed multiple deficiencies, including in-process specification exceedances, incomplete process monitoring data, and unexplained gaps in critical parameters.

FDA recommended the engagement of a qualified CGMP consultant to conduct a comprehensive six-system audit before the firm pursues resolution of its compliance status.

For further information, please refer to the full Warning Letter to ABS Corporation, Omaha, Nebraska, on the FDA website.