FDA Warning Letter: serious GMP Deficiencies at a Chinese API Manufacturer

In a Warning Letter dated 6 August 2026, the US Food and Drug Administration (FDA) accused Tianjin Kilo Pharmaceutical Sci-tech Co., Ltd. of significant violations of Good Manufacturing Practice (GMP) requirements for active pharmaceutical ingredients (APIs). The main concerns are missing process validation, incomplete manufacturing documentation, unvalidated analytical methods and an inadequate stability programme. In addition, the Chinese company is alleged not to have listed two medicinal products under its own labeler code. The FDA has already placed the company's products on Import Alert 66-40.

No process validation for APIs supplied to the USA

According to the FDA, Tianjin Kilo manufactured APIs and supplied them to the USA without first conducting appropriate process validation studies. The company reportedly told the authority that the APIs concerned were still under development and were not commercial products. Consequently, standard operating procedures and formal validation documents, among other things, had not yet been finalised.

However, FDA data showed that the APIs were distributed to US 503A compounding pharmacies. In the authority's view, this meant that there was no basic evidence that the manufacturing processes could reproducibly produce the APIs with the intended quality and purity.

The FDA therefore requires, among other things:

• a comprehensive description of the validation programme covering the entire product lifecycle,
• timetables for Process Performance Qualification (PPQ),
• qualification protocols for equipment and facilities, and
• a risk assessment of the APIs that had already been manufactured and distributed without process validation.

Incomplete or missing manufacturing documentation

Another key criticism concerns the master production and control records. According to the FDA, at least one batch record submitted lacked important information on critical process steps. Certain process parameters and essential equipment, among other things, had not been specified.

For another API, Tianjin Kilo did not submit a batch record at all, despite repeated requests. Without complete and adequately detailed manufacturing documentation, it is not possible to reliably monitor and assess process variability within a batch or between different batches.

The FDA therefore requires:

• an independent worldwide review of the production processes,
• complete master batch records for all APIs offered on the US market, and
• appropriate documentation of all essential manufacturing steps and the equipment used.

Analytical test methods not validated

According to the Warning Letter, the company's laboratory system also has significant deficiencies. For the chemical and microbiological test methods used for APIs distributed in the USA, Tianjin Kilo had conducted neither adequate method validation nor, where pharmacopoeial methods were used, the corresponding verification. As a result, the necessary scientific basis for reliably determining the identity, assay, quality, purity and potency of the APIs was lacking.

The FDA requires, among other things, the following measures:

• an independent assessment of laboratory practices, test methods and equipment,
• a review of the documentation and qualifications of laboratory personnel, and
• a complete list of all chemical and microbiological test methods used.

No robust stability programme

The FDA also found that Tianjin Kilo had not established a documented, ongoing stability programme. No stability data were submitted for at least one API manufactured at the site. In the authority's view, this meant that there was no evidence that the APIs would maintain their specified quality attributes throughout the stated shelf-life or retest periods under the intended storage conditions.

The requirements include, among other things:

• a retrospective risk assessment for APIs already placed on the market,
• a comprehensive CAPA programme for stability testing,
• stability studies in the marketed packaging systems,
• appropriate stability-indicating test methods,
• a precise definition of the quality attributes and time points to be tested, and
• annual monitoring of representative batches.

Violations relating to drug listing

In addition to the GMP deficiencies, the FDA criticised violations of the requirements for drug listing. Tianjin Kilo allegedly did not list the medicinal products Demecarium bromide and Chlorambucil under its own labeler code, even though the company had manufactured and shipped the products to the USA. According to the FDA, the products were listed, but under another company's labeler code. In the FDA's view, they were therefore incorrectly labelled or "misbranded".

Possible regulatory consequences

On 21 July 2026, the FDA placed all of the company's medicinal products and drug products intended for import into the USA on Import Alert 66-40. The authority may also withhold approvals or supplements listing Tianjin Kilo as the manufacturer until the deficiencies have been fully corrected and GMP compliance has been confirmed. The company must respond in writing within 15 business days of receiving the letter and submit specific corrective and preventive actions. The FDA reserves the right to conduct a further inspection to verify the implementation and effectiveness of the measures.

Please see the FDA website for the full contents of the Warning Letter.