As regulatory expectations for sterile manufacturing continue to evolve, the updated EU GMP Annex 1 guidelines have placed renewed emphasis on contamination control, risk-based validation strategies, and demonstrable patient protection. For organisations operating in fill and finish, this shift requires a validation approach supported by data and grounded in quality risk management.
Markus Junior Maring, product manager, Filtration Consumables, and Marine Cannuel, manager of validation services, Sartorius, examine how specialised validation services can help manufacturers strengthen Annex 1 compliance. Using real‑world case studies, they illustrate how collaborative, risk‑based validation approaches support effective contamination control strategies (CCS) across fill and finish operations.
Sartorius
The importance of validation services for Annex 1 compliance
Annex 1 places contamination control at the centre of sterile product manufacturing. The guidelines explicitly link CCS to patient protection, emphasising that risks related to microorganisms, endotoxins, pyrogens, and particles must be systematically identified, assessed, and mitigated. Accordingly, selecting the right validation strategy is critical to a robust CCS.
The new regulations also reinforce the importance of quality risk management as a practical tool. Validation strategies must clearly demonstrate that material selection, process controls, and operating conditions are appropriate for the intended use and associated risk profile. This includes defined approaches to filter sterilisation, integrity testing of single‑use materials, implementation of pre‑use post‑sterilisation integrity testing (PUPSIT), and risk‑based extractables and leachables assessments in line with United States Pharmacopeia (USP) <665>.
The purpose of process validation is to ensure that processes are designed and operated with patient protection as the central priority. This is achieved through a structured approach that begins with fundamental scientific knowledge, which is translated into regulatory frameworks and applied to process understanding. With this foundation, risk assessments can be performed to evaluate whether contamination control and validation strategies are scientifically justified.
While validation services provide technical expertise and generate critical supporting data, responsibility for compliance ultimately remains with the process owner. This shared responsibility highlights the importance of early collaboration, clear communication, and strong alignment between manufacturers and validation service providers.
Material Selection: A scientific, risk‑based process
Material selection should be driven by a clear assessment of risk, including the evaluation of chemical compatibility between the process formulation and single-use materials, as well as the potential for extractables and leachables to enter the process stream. Because single-use systems are composed of polymers, these considerations require detailed assessment.
Additional factors must also be considered. For sterile filtration, retention performance is critical to ensure effective removal of microorganisms under process conditions. Integrity assurance extends beyond standard filter testing to include bags and assemblies, with defined acceptance criteria. Sterilisation methods must be selected and assessed for their impact on material performance and process parameters.
Operational conditions further influence risk. Stability under process-relevant pressures, flows, and temperatures must be understood, particularly for demanding applications. Interactions between the product and materials, such as binding effects, should also be evaluated alongside chemical compatibility.
These material-related risks directly inform the validation strategy and the selection of appropriate studies to demonstrate control. Across fill and finish operations, this includes testing at multiple stages — from drug substance freezing and thawing through drug product filtration and microbiological challenge testing, to container closure systems. Extractables and leachables assessments are required for all polymeric product-contact materials, while final product stages may also involve validation of visual inspection processes. Supporting studies, such as shipping simulations and stability assessments, are also required depending on the application.
Case Study 1: PUPSIT Simulation During Bacterial Challenge Testing
Challenge
With the implementation of Annex 1, PUPSIT has become a key focus for sterile filtration processes. While PUPSIT is intended to prevent filter flaws from being masked by subsequent interaction with the process fluid, regulators and process owners have raised concerns about how repeated integrity testing and sterilisation cycles may affect filter performance.
Approach
To address this, we collaborated with GSK to develop a structured, risk‑based approach that integrates PUPSIT simulation into bacterial retention testing.1 Together, we evaluated worst‑case process parameters, including sterilisation method, wetting fluids, applied pressures, integrity test repetitions, and bioburden challenge levels, to develop a process-specific PUPSIT strategy.
By incorporating PUPSIT conditions directly into bacterial challenge testing, we were able to assess filter robustness under realistic process conditions and generate data specific to the intended use.
Outcome
More than 35 PUPSIT‑BCT studies were successfully completed using process‑specific conditions. The results demonstrated that incorporating a PUPSIT simulation phase into filter validation is both proactive and feasible, providing data that support regulatory scrutiny.
For GSK, this approach delivered increased confidence in the filter validation strategy, alignment with Annex 1 expectations, and positive feedback from regulators on the collaborative, risk‑based methodology. While PUPSIT simulation during bacterial retention testing is not mandated by regulators, its inclusion has been well received. Generating these data is viewed as a proactive and risk-based evaluation of PUPSIT implementation and its potential impact on the filter’s ability to achieve sterilisation, supported by data-driven rationales.
Case Study 2: Process Risk Analysis for Extractables and Leachables
Challenge
The use of multiple single‑use systems in fill and finish introduces potential extractables and leachables risk that must be evaluated to ensure patient safety. Performing full testing on every component, however, can be resource‑intensive and may not be scientifically supported.
Approach
In this case, we supported a customer by conducting a structured process risk analysis for extractables and leachables across seven single‑use systems used in drug product manufacturing.
The process risk analysis evaluated five key parameters for each system: location within the process, contact time, temperature, nature of the solution, and dilution rate. Risk levels were calculated using established guidance from BioPhorum and USP <1665>, allowing systems to be categorised as low, medium, or high risk.
If the single-use system was classified as low risk, we advised that it was sufficient to accept data from the manufacturer (e.g., validation guides and extractables guides). If the risk was evaluated as medium, we recommended that the customer perform an extractables assessment, using data generated under worst-case test conditions to evaluate all potential extractables from the material. For high-risk systems, we recommended that leachables analysis be performed under laboratory conditions, mimicking the process conditions.
Outcome
The analysis showed that only three of the seven systems were high-risk, requiring full leachables testing, while the remaining four were medium-risk and could be addressed through extractables assessments and safety evaluations. This risk‑based approach ensured regulatory compliance while reducing validation effort, cost, and timeline.
Our customer achieved compliance with Annex 1 and related GMP guidelines while benefiting from a focused, scientifically justified validation strategy tailored to actual process risk.
Case Study 3: Visual Inspection of Foreign Material in Intravenous Bags
Challenge
Visual inspection for visible particles is mandatory for container closure systems, whether performed manually or using automated equipment. Our customer sought support in validating visual inspection for foreign material in intravenous (IV) bags, both before and after filling.
Compared to glass vials, the opacity and flexibility of IV bags present additional challenges when preparing representative inspection standards.
Approach
To address this, we developed customised training kits consisting of IV bags containing foreign particles of known size. These kits enabled operators to practice and validate visual inspection techniques without contaminating the tubing or compromising system integrity.
Outcome
The solution enabled effective visual inspection training both before and after filling, allowing operators to observe particle behaviour within the bag under realistic conditions. This approach supported compliance with USP, European Pharmacopoeia, and Annex 1 requirements while improving inspection consistency and operator confidence.
Supporting risk-based validation decisions
These case studies illustrate that validation is most effective when structured as a collaborative, risk‑based process. While responsibility remains with the manufacturer, validation services contribute structured methodologies, technical expertise, and robust data to support informed, defensible decisions.
As regulatory scrutiny continues to increase, expert‑driven validation services are becoming increasingly important. Grounding validation in scientific understanding, process knowledge, and risk assessment strengthens contamination control and supports consistent product quality and patient safety.