FDA Warning Letter to US Manufacturer Highlights Laboratory Deficiencies

At the end of February, the U.S. Food and Drug Administration (FDA) has published a Warning Letter dated 12 February 2026. During an inspection performed in August 2025, the agency uncovered systemic quality control failures at a pharmaceutical manufacturing facility in Lynden, Washington, raising questions about product safety and compliance with basic testing requirements.

Microbiological Testing Deficiencies

A key focus of the inspection was the absence of adequate microbiological testing for finished drug products. The firm failed to establish scientifically sound and appropriate specifications for objectionable microorganisms and did not ensure that each batch was tested prior to release. As a result, there was no documented evidence that distributed products met basic microbiological quality requirements.

Materials, Procedures & Supplier Oversight

Inspectors also highlighted shortcomings in written procedures for handling, testing, and approving materials and components. The firm released products made with inadequately tested components and relied on supplier certificates of analysis without ensuring their reliability.

Stability Program Gaps

The company did not implement an adequate stability testing program to support labeled expiry periods. Missing or insufficient stability data undermine assurance that products maintain their identity, strength, quality and purity throughout their shelf life. The absence of a scientifically designed stability program represents a critical compliance gap.

Quality Unit Oversight of Laboratory Operations

The Warning Letter also pointed to weaknesses in the Quality Unit’s authority and oversight. Laboratory activities were not effectively supervised, and batch disposition decisions were made without complete and reliable analytical evidence. The FDA expects the Quality Unit to ensure that laboratory systems are compliant, validated and fully controlled.

The FDA requested a comprehensive remediation plan, including an independent assessment of laboratory systems, a retrospective evaluation of distributed batches, implementation of validated analytical methods, and the establishment of a scientifically sound stability program.

For further information, please see the complete Warning Letter to AQ USA Inc., d.b.a. Ross Healthcare Inc., published on the FDA’s website.