The latest revision of EU GMP Annex 1: Manufacture of sterile medicinal products guides the manufacturing of sterile medicinal products to protect product quality and ensure patient safety. It includes requirements for cleanroom design, operation, and monitoring.
The impacts of Annex 1 extend worldwide. Any manufacturer that supplies sterile medicines to the European Union (EU) market must comply with Annex 1, no matter where in the world they are located.
This article explores the implications of Annex 1 and its expectations for contamination control. The focus is on practical steps: adapting facilities, aligning teams, and using Annex 1 as a roadmap for cleaner, safer, and globally competitive operations.
Contamination control strategy as a central part of Annex 1
Compared to other familiar standards, Annex 1 takes a broader and more integrated approach. Created with input by the European Medicines Agency (EMA), Pharmaceutical Inspection Convention and Pharmaceutical Inspection Co-operation Scheme (PIC/S), and the World Health Organization (WHO), with contributions from the FDA, Annex 1 satisfies regulations and recommendations from several major regulatory bodies.
Annex 1 and the FDA’s Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing are the two most closely aligned standards for sterile manufacturing. They both anchor their cleanroom classification in ISO 14644-1 and focus on environmental monitoring, facility design, process design, and qualification to ensure contamination control. It’s valuable to note that Annex 1 applies to mandatory aseptic and terminal sterilization processes, while the FDA guidance only concerns aseptic processes and is not legally enforceable.
Importantly, Annex 1 introduces the Contamination Control Strategy (CCS) as a central organizing principle.
A CCS is a facility-wide framework that defines how a company prevents, monitors, and manages contamination risks across its operations. Annex 1 states that “a CCS should be implemented across the facility in order to define all critical control points and assess the effectiveness of all the controls (design, procedural, technical, and organizational) and monitoring measures employed to manage risks to medicinal product quality and safety.”
To create a CCS, Annex 1 requires one to:
- Map out all potential sources of contamination
- Implement controls and monitoring measures to manage risks
- Support these controls with documented risk assessments
- Regularly assess the effectiveness of these controls and measures
- Actively review and update the CCS to support continuous improvement of manufacturing and control methods
Annex 1 requires manufacturers to view controls collectively rather than as isolated activities. In practice, this means collaboration between engineering, operations, and quality teams to integrate technical and procedural controls into a unified strategy that minimizes contamination risks and supports regulatory compliance.
Design and operational implications of Annex 1
Airflow and HVAC systems
Annex 1’s airflow requirements are designed to ensure that air from less clean areas never flows into higher-grade zones. Cleanrooms achieve this through unidirectional airflow and by maintaining a positive pressure relative to the background environment. Annex 1 specifies that “adjacent rooms of different grades should have an air pressure difference of a minimum of 10 pascals (guidance value).”
The regulation also emphasizes the importance of visualizing airflow. As stated in Annex 1, “Airflow patterns within cleanrooms and zones should be visualized to demonstrate that there is no ingress from lower grade to higher grade areas and that air does not travel from less clean areas (such as the floor) or over operators or equipment that may transfer contaminant to the higher grade areas.” These studies must be performed both at rest and in operation, with video recordings retained, and their results factored into the environmental monitoring program.
The movement of personnel and materials
To minimize contamination, Annex 1 emphasizes the importance of airlocks between cleanroom areas of different grades. These transitional spaces act as barriers that maintain pressure differentials and control particle flow. The guideline specifies that personnel and materials should, whenever possible, use separate airlocks to avoid cross-contamination. When separate airlocks aren’t feasible, facilities should establish clear procedures for time-based separation—ensuring that people and materials don’t move through the same space simultaneously. Annex 1 also notes that pass-through hatches and airlocks must be designed so their entry and exit doors cannot be opened at the same time. To enforce this, Grades A and B cleanrooms require interlocks, while Grades C and D must have at least a visual or audible warning system to alert operators.
These measures prevent cleanrooms from being compromised by their greatest risk factor: people and materials moving through them.
Barrier systems
Annex 1 encourages facilities to use barrier technologies, such as Restricted Access Barrier Systems (RABS) and isolators, to separate Grade A environments from the background environment, thereby reducing the risk of contamination. According to Annex 1, “Any alternative approaches to the use of RABS or isolators should be justified.”
RABS can be classified as open or closed. Open RABS allows doors to be opened for operator intervention under predefined and controlled conditions. Closed RABS operate with all doors closed, providing stronger separation from the surrounding environment. In both cases, RABS provide an enclosed, but not fully sealed, environment. Their inner surfaces must be disinfected and decontaminated before and after operations, which introduces variability and depends on personnel following procedures carefully. Annex 1 requires RABS to maintain Grade A conditions with uninterrupted, unidirectional airflow and a positive pressure relative to the background area.
Isolators are also available in open and closed designs. Closed isolators provide the highest level of separation, with material transfer occurring only via aseptic connection to auxiliary equipment. Isolators can maintain Grade A conditions even in lower-class background areas, and many feature automated bio-decontamination cycles that improve reproducibility and reduce reliance on manual procedures. These advantages make them especially suited for aseptic filling lines and high-risk products requiring maximum sterility assurance.
Qualification and requalification as proof of control
Annex 1 requires that cleanrooms and clean air equipment be qualified to demonstrate that they meet the characteristics needed for sterile manufacturing. Qualification follows the principles of Annex 15, using a series of defined tests. These typically include filter integrity testing, airflow volume and velocity, pressure differentials, airflow visualization, recovery time, microbial contamination, and checks of temperature and humidity.
To maintain control, cleanrooms and clean air equipment must be requalified at a maximum of every six months for Grade A and B areas, and every twelve months for Grade C and D. Requalification is also required after significant changes, such as filter replacement, HVAC adjustments, or design modifications. Together, qualification and requalification ensure that contamination risks are understood and continuously controlled throughout the cleanroom lifecycle.
Environmental monitoring
A cleanroom may meet design specifications on day one, but regulators expect ongoing evidence that it continues to perform as intended. For this reason, environmental monitoring is an essential element of the CCS.
Annex 1 monitoring requirements are tiered according to cleanroom classification. For example, Grade A zones demand continuous monitoring for total and viable particles, whereas Grade B zones can have a decreased sampling frequency, but must be monitored often enough, with sufficient sample size, to detect rising contamination or system deterioration.
Traditional microbiological tools still anchor Annex 1’s expectations for environmental monitoring. Settle plates, contact plates, and active air samplers are standard for detecting viable contamination on surfaces and in the air. Additionally, aseptic process simulations, also known as media fill, are necessary to demonstrate that aseptic processes can be performed reliably under routine operating conditions. These methods provide evidence supporting the effectiveness of the controls.
In recent years, rapid microbiological methods have gained traction. Annex 1 acknowledges that these technologies can expedite the detection of microbiological contamination, but requires them to be validated to demonstrate equivalence or superiority to established methods.
Implementation challenges
Adopting Annex 1 can be straightforward for new facilities but far more complex for legacy sites. Retrofitting older cleanrooms to meet modern CCS requirements often demands reconfigured airflows, upgraded barrier systems, or new monitoring technology.
Beyond the technical hurdles, global manufacturers must reconcile Annex 1 with other frameworks such as FDA guidance. The overlap is significant, but differences in scope or terminology can cause confusion if not addressed systematically.
Perhaps the biggest challenge is cultural. Quality teams cannot assume sole responsibility for the CCS. Operations, engineering, and quality assurance must all accept shared responsibility for contamination control.
Practical advice for implementation
A structured approach helps make Annex 1 manageable.
Start with a gap assessment to identify where current practices diverge from Annex 1 expectations, then build a CCS that sets priorities and responsibilities. Early collaboration with cleanroom designers, validation specialists, and quality experts ensures that solutions are practical and sustainable.
Finally, Annex 1 stresses that “senior management should effectively oversee the state of control throughout the facility and product lifecycle”. Rather than a one-off event, contamination control is a continuous loop of qualification, review, monitoring, and requalification. Embedding this mindset into daily operations prevents unexpected findings during inspections.
Shaping facilities for compliance, quality, and global reach
Viewed narrowly, Annex 1 is another regulatory requirement. Viewed strategically, it is a blueprint for global readiness, reflecting a harmonized vision shaped by the EMA, PIC/S, and WHO, with contributions from the FDA. Facilities that implement its principles strengthen product quality, build confidence with regulators, and position themselves for long-term success in international markets.
