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Jan 20, 2026 - Cosmetics

USDrugAdministrationcallsforcomprehensivereviewofdesign,monitoringandmicrobiologicalcontrols

US Drug Administration calls for comprehensive review of design, monitoring, and microbiological controls

In a recently released Warning Letter, the U.S. Food and Drug Administration (FDA) criticized significant deficiencies in the water system of a manufacturer of oral and topical drugs. The agency’s criticism is directed at both the technical design of the water system and what the FDA considers insufficient microbiological monitoring.

According to the FDA, the water system showed so-called “dead-legs” at each tap point. These are pipe sections with insufficient flow where water can stagnate. According to the agency, this stagnation favors the formation of biofilms, posing a significant microbiological risk for drug manufacturing.

In addition, the FDA criticized that the manufacturer did not conduct adequate tests for objectionable microorganisms. In particular, there were no tests for the Burkholderia cepacia complex (BCC), which is considered critical in the pharmaceutical industry because it is water-loving and can pose a health risk, especially for immunocompromised patients.

Other criticisms concerned the use of alternative microbiological testing methods that, according to the FDA, were not validated. Furthermore, the manufacturer could not provide sufficient evidence of the suitability of the culture media used. This also contradicts the requirements for controlled and safe drug production, according to the agency.

As a consequence, the FDA calls for a comprehensive and independent assessment of the entire water system. In addition to a review of the system layout, the agency requires the implementation of an appropriate maintenance and monitoring plan for the water system. Furthermore, clear microbiological limits and guidelines must be established, regularly reviewed, and documented. Another central point of the Warning Letter is the demand for a detailed and systematic risk assessment that identifies potential hazards to product quality and patient safety and addresses them appropriately.

The case once again underlines the central importance of qualified water systems for pharmaceutical manufacturing. Experts point out that, particularly in non-sterile drugs, water systems often represent one of the main sources of microbiological contamination. Accordingly, the regulatory expectations for the design, operation, and monitoring of such systems are high.

Companies that manufacture drugs can obtain external support for microbiological and hygienic issues. The range of services extends from the selection and validation of suitable testing methods to the establishment of limits and on-site inspections and hygiene checks.

Source: GMP Navigator – “What did the FDA criticize about the design of a water system?”