FDA Warning Letter: Several Analytical Deficiencies Identified at Chinese Manufacturer

Following an inspection in March 2025, the U.S. Food and Drug Administration (FDA) issued a Warning Letter dated 30 September 2025, highlighting significant failures in analytical quality control.

The agency noted that batches of OTC drug products were released without adequate testing for identity and strength of the active ingredients. This included a repeat observation from an earlier inspection, emphasizing persistent deficiencies in release testing strategy and oversight.

The agency further criticized the lack of scientifically sound and validated analytical methods. Test procedures were based on the Chinese Pharmacopoeia without demonstrated equivalence to current USP methods. The FDA pointed out that firms must ensure method suitability, including validation and system suitability checks, to confirm that products meet established quality attributes throughout their shelf life.

Stability data were also a central concern. The firm did not maintain an adequate stability testing program to confirm the maintenance of quality attributes over the labeled expiry period. Proposed corrective measures, including annual testing, lacked scientific rationale and did not meet regulatory expectations for ongoing stability monitoring.

In addition, the FDA identified significant data integrity problems. Laboratory systems, including UV-Vis and IR instruments, lacked audit trail functionality, allowing analysts to alter or delete electronic records without detection.

All products manufactured at the site have been placed on Import Alert 66-40, meaning they may be detained without physical examination upon entry into the United States. The FDA may also withhold approval of pending or future applications until sustainable compliance is demonstrated.

For further information, please see the full Warning Letter to Guangxi Yulin Pharmaceutical Group Co. Ltd. on the FDA's website.