FDA Warning Letter to EU OTC Manufacturer

On 05 May 2026, the U.S. Food and Drug Administration (FDA) published a Warning Letter dated 20 April 2026 to an EU-based manufacturing site.

The company, located in Brno, Czech Republic, is registered with the FDA as a manufacturer of over-the-counter (OTC) drug products. The FDA reviewed documents submitted in response to an official request for records and other information pursuant to section 704(a)(4) of the Federal Food, Drug, and Cosmetic Act (FD&C Act).

The Warning Letter highlights several significant CGMP deficiencies, including:

• Incoming material control: failure to perform at least one test to verify the identity of each component, and failure to establish the reliability of suppliers’ analyses at appropriate intervals (21 CFR 211.84(d)(1)/(2)). FDA also points to insufficient testing of high-risk components for relevant contamination/impurities prior to use.
• Stability program: absence of an adequate written stability testing program and a lack of stability studies despite expiry dating on labels (21 CFR 211.166(a)), leaving shelf-life claims without scientific support.
• Process validation and process control: inadequate written production and process control procedures and insufficient validation to demonstrate reproducible, controlled manufacturing processes (21 CFR 211.100(a)).
• Analytical methods and microbiological control: insufficient validation/verification of test methods (21 CFR 211.165(e)), including inadequate evidence of specificity, accuracy and robustness for assay testing. FDA also questions the rationale for reduced microbiological testing, citing missing supporting validation, stability data and a comprehensive microbial risk assessment.
• Data integrity / completeness of lab records: laboratory records and CoA documentation did not include complete data, e.g., reporting “passed” without providing individual numerical test results for certain attributes (21 CFR 211.194(a)).

Given the breadth of observations, FDA recommends engaging a qualified CGMP consultant (21 CFR 211.34) to support remediation, including a comprehensive six-system audit and verification of CAPA effectiveness.

The FDA requests a written response within 15 working days detailing corrective actions and timelines. The agency also notes potential regulatory consequences if deficiencies are not addressed, including withholding approvals for applications listing the manufacturer and possible refusal of admission of affected products into the U.S. market.

For further information, please see the complete Warning Letter to Respilon Production S.R.O. on the FDA's website.