FDA Cites Airflow, Aseptic Conditions and Visual Inspection at Korean Manufacturer

The FDA inspected the drug manufacturing operations of a sterile manufacturer in South Korea in April 2026. The Warning Letter dated 2 October 2026 summarises serious violations of the CGMP regulations for sterile finished drug products.

Deficient Aseptic Procedures and Behaviour in the Cleanroom

During set-up and filling operations, the FDA repeatedly observed behaviour that interrupts the first-air principle: staff placed their arms, upper bodies and heads over open sterile tubing and other open containers (designation redacted in the original). In addition, auxiliary items were used directly above open bottles, closures and caps. One employee worked in a Grade A area wearing visibly soiled cleanroom clothing.

Inadequate Airflow Visualisation

According to the FDA, the dynamic airflow visualisations (smoke studies) do not demonstrate that the airflow adequately protects the aseptic line. With the barrier system open, air flows upwards at a sharp angle towards the exhaust openings, so critical areas remain unprotected during interventions. The FDA describes this as a fundamental design flaw through which lower-quality air from the surrounding Class 10,000 (ISO 7) area can enter Class 100 (ISO 5). The FDA further object to design deficiencies in the production equipment which lead to unfavourable ergonomics and to aseptic practices that impair unidirectional airflow. In addition, the airflow visualisations are incomplete, as they do not adequately show the direction of flow during critical activities.

The company's response envisages redesigning the filling line, new smoke studies after the modification, and training and qualification of personnel. The FDA acknowledges these commitments but considers the response inadequate. A comprehensive programme for monitoring personnel behaviour in production is lacking, which the FDA views as particularly critical given its earlier findings on aseptic behaviour. Furthermore, fundamental improvements were missing, such as how airflow visualisations are to be carried out, and quality assurance measures for the objective assessment of future studies by qualified experts.

Cleaning and Sterilisation of Equipment

The FDA finds that the aseptic process is not designed to prevent contamination of the sterile products. According to the FDA, critical contact surfaces with containers and closures are not appropriately sterilised but merely wiped with sporicidal disinfectants. However, the authority considers that only sterile equipment parts may come into contact with the sterile formulation, containers and closures. The FDA requires a comprehensive risk assessment of all contamination hazards for aseptic processes, equipment and rooms, including personnel and material flows as well as disinfection practices, and, based on this, a CAPA plan with deadlines.

Deficient Environmental Monitoring

The FDA considers the environmental monitoring of critical areas inadequate. Locations and frequencies for microbiological sampling of air and surfaces, as well as for particle monitoring, are not sufficiently justified and are unsuitable for detecting contamination risks in good time. In particular, sampling of the environment around containers and closures, and of the surfaces of the barriers facing the ISO 5 areas, is missing. Without an adequate programme, there is no daily evidence of environmental control, which is fundamental to the sterility of aseptically manufactured products. The FDA requires the environmental monitoring to be revised as part of the risk assessment and the CAPA plan.

Inadequate Visual Inspection

The FDA criticises the programme for 100% visual inspection of sterile products. Defects are not routinely categorised, and appropriate limits are lacking. The authority also points to considerable defect rates. Foreign matter deserves particular attention, as it may indicate unhygienic or microbial contamination and requires thorough investigation and appropriate CAPA. The FDA requires an independent assessment and remediation of the programme. This includes defining critical, major and minor defects with individual limits, qualifying the test methods and personnel, incorporating deviation data, complaints and recalls, and, where appropriate, destructive testing with statistically sound sample sizes.

Please see the FDA website for the full Warning Letter to the Korean sterile manufacturer.