FDA Uncovers Critical Manufacturing Violations at Chinese API Makers
The FDA put two Chinese API makers on import alert after failed inspections.
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Chinese API producers Wuhu Nuowei Chemistry and Chengdu Innovation Pharmaceutical are under US import alert due to quality control and testing concerns. Wuhu Nuowei marked some API batches as “For R&D only” for the US; however, the FDA reported that the batch sizes were “inconsistent with quantities” typical for R&D, as noted in the warning letter from Tuesday.
The company claimed that products shipped to the US were from one of its customers. Following this, Wuhu Nuowei has ceased API shipments to the US and is no longer registered as a drug manufacturer. Additionally, the company failed to validate its testing methods for API purity and did not provide complete records on raw stability data, according to the FDA. The letter indicates that there is insufficient evidence to support that the manufacturer’s testing methods are “scientifically sound” and comparable to those used in the US.
Chengdu also did not adequately test incoming materials for products shipped to the US market, including its APIs, as highlighted in its warning letter. The manufacturer lacked a competent quality unit to supervise its drug production process, resulting in inadequate screening of materials for quality. The FDA suggested that Chengdu engage a third-party consultant to address these issues. If the company fails to implement necessary changes, the agency may block new drug applications that list Chengdu as the manufacturer.
Let’s take a closer look at these warning letters and pull some important lessons from them.
Testing method validation failures
A September 2024 FDA inspection of Wuhu Nuowei's facility in Jingde revealed problems with the company's analytical testing methods. The company had been using testing procedures based on Chinese Pharmacopeia standards without validating their equivalence to USP requirements. This deviation is particularly significant for their API product, which is commonly used in medical treatments (though the specific application was redacted in the warning letter).
The disparity between acceptable impurity levels was dramatic. Wuhu Nuowei's specifications allowed for significantly higher impurity levels than USP standards:
The company's single impurity limit exceeded the USP specification of the redacted percentage.
Their total impurities threshold surpassed the USP limit of the redacted percentage.
At least one batch shipped to the United States exceeded USP monograph specifications for individual impurities.
On top of this, the company's release testing protocol omitted required testing for specific related compounds, rendering their quality control process incomplete by USP standards.
Stability testing deficiencies
The FDA's inspection also uncovered serious gaps in Wuhu Nuowei's stability testing program. When asked to justify its API's retest date, the company could not produce raw stability data for multiple batches, including lots identified explicitly in the warning letter.
In case it isn’t clear, a failure like this undermines confidence in the company's ability to ensure product stability throughout its claimed shelf life — and raises questions about the scientific basis for its stability claims.
Equipment cleaning validation
The company's approach to equipment cleaning validation was found to be particularly concerning. For shared manufacturing equipment used to produce multiple APIs, Wuhu Nuowei:
Relied solely on visual inspection to determine cleanliness.
Had no acceptance criteria for carryover residues.
Could not provide analytical or microbiological data to support cleaning efficacy.
Failed to establish proper cleaning procedures for all manufacturing equipment.
This lack of rigorous cleaning validation obviously raises significant concerns about potential cross-contamination between different APIs manufactured using the same equipment.
An R&D labeling controversy
In a particularly notable finding, the FDA identified what appears to be an attempt to circumvent regulatory requirements through misleading labeling. While Wuhu Nuowei labeled some API shipments as "For R&D only. Not for commercial" use, the quantities involved — with some shipments containing redacted amounts that the FDA noted were clearly commercial scale — were inconsistent with typical research and development purposes.
The company's attempt to distance itself from U.S. distribution by claiming that shipments were handled by a customer (whose name was redacted) rather than directly by Wuhu Nuowei suggests a concerning lack of transparency in their regulatory compliance approach.
Raw material testing deficiencies
Now, moving to the other warning letter, the FDA's review of Chengdu Innovation Pharmaceutical's records revealed fundamental gaps in its quality control processes. Most critically, the company failed to perform basic identity testing on incoming raw materials before using them in API production. This oversight means there was no scientific evidence that raw materials met quality specifications before being incorporated into finished products — a massive problem.
Quality unit authority and oversight
The investigation exposed systemic failures in Chengdu's quality unit (QU) operations, including: