FDA Warning Letter: Deficiencies in Incoming Component Testing, Stability Program, and Data Integrity Controls

The U.S. Food and Drug Administration (FDA) has published a new Warning Letter dated 14 May 2026 to a drug manufacturing facility in Illinois, following an inspection conducted in November 2025. The letter cites significant CGMP violations with an analytical/QC emphasis.

The agency highlights three interlinked failures: insufficient incoming-material testing, lack of stability data to justify expiry, and data integrity / quality unit oversight weaknesses.

Testing of Incoming Components

FDA states the firm did not test each component lot adequately for identity and conformance to appropriate specifications (purity/strength/quality). A key example involves a critical component where only limited testing was performed, while the relevant USP monograph calls for additional chemical purity and microbiological quality testing. FDA also notes missing fundamentals such as defined sampling requirements and acceptance criteria.

The FDA also describes that identity testing was not performed on each shipment of each lot for certain high-risk materials using the USP identification/limit testing approach intended to detect such impurities. Because these identity/limit tests were not performed lot-by-lot before use, FDA concludes the firm did not adequately assure component suitability, with potential patient safety implications.

Stability Program

The authority indicates the firm lacked a compliant written stability program and did not generate adequate long-term/accelerated data to show products remain within specification throughout labeled expiry. The cited example points to extremely limited stability information (e.g., a single batch, limited conditions, and missing controlled humidity), and FDA states there were no ongoing stability studies for currently manufactured drugs.

Data integrity and Quality Unit Oversight

The FDA describes inadequate laboratory data governance and electronic record controls. According to the Warning Letter, the "investigator documented an uncontrolled password" for an analytical instrument "affixed to a laptop by a sticker" and the "data [...] is automatically deleted when the laptop is shutdown, so no records were available to show that [the] QU reviewed this data."  In addition, FDA notes failures in routine quality-system activities (e.g., annual product reviews).

For further information and a detailed overview of the corrective actions requested by FDA, please refer to the full Warning Letter to GC America, Inc. on the FDA website.