Richard Chai- Senior Technical Service Manager, STERIS Corporation; David J.W. Barber- Consultant.
Introduction
The EU Rules for Manufacture of Medicinal Products GMP, published in 1989, contained an annex on the manufacture of sterile medicinal products to ensure the sterility of medicinal products. A version of this annex, “Annex 1”, issued according to its document history in May 2003, underwent several targeted updates in the interim period until 2009, but now Annex 1 has undergone, for the first time, a complete revision.1
The new version of Annex 1, released on 22 Aug 2022, is a comprehensive revision to the previous Guideline, which covers all aspects related to the facilities, utilities, equipment, and systems and controls used for the production of sterile medicinal products. This includes sections on aseptic preparation and processing, and Aseptic Process Simulation (APS), and media fill. There is much interest regarding additions to this latest revision of Annex 1, which has much more detail compared to previous versions. In this article, we have reviewed the section on Aseptic Process Simulation (APS), which previously consisted of five brief paragraphs, and now consists of four pages– approximately a 300% increase in the content related to APS. Drawing on our recent publications regarding the application of media simulations in the validation of aseptic processes,2,3 this article aims to assess the changes and additional requirements related to APS.
Aseptic Process Simulation (APS): Process Design
In the updated Annex 1, Section 9 “Environmental and Process Monitoring” paragraphs 9.32 to 9.49 discuss Aseptic Process Simulation (APS) commonly known as media fill. Paragraph 9.32 stresses the importance of process design, adherence to pharmaceutical quality systems, process controls, training, and evaluation of monitoring data to ensure an effective aseptic manufacturing process. If the actual processing conditions during APS affect the viability of potential microbial contaminants, alternative procedures that function as closely as possible to the actual operation should be used. Paragraph 9.32 also mentions “surrogate materials”, or substitute materials such as buffer solutions that may be used in parts of the APS. If used, it is important to ensure they do not inhibit the growth of microorganisms. (“Surrogate” is not defined in the glossary.)
In paragraph 9.33, Annex 1 states that the APS should imitate the routine aseptic manufacturing process as closely as possible and include all the critical manufacturing steps. While this is not a new requirement, the following steps are new:
- The scope of the APS should include all aseptic operations after the sterilization and decontamination of materials to the point where the containers are sealed.
- Non-filterable products should have additional or other aseptic steps considered.
- Process air should be used instead of inert gas to promote the growth of microorganisms. An exception to this is when anaerobes have been isolated from these systems, and APS is performed specifically to detect anaerobes in these systems.
- Surrogate materials can be used in place of sterile powders in the same containers.
- Individual simulation for unit operations should be avoided unless supported by documented justification, ensuring all the unit operations APS add up to cover the whole process.
Lyophilization
The APS requirement for lyophilization is also introduced in this new Annex 1. The main consideration is to simulate all aspects of the lyophilization process including filling and transport of vials. There are some exceptions where the simulation process may have an impact on the recovery of the microorganisms, such as using process air instead of nitrogen during vacuum break or causing boiling-over or freezing of the media. Elements to consider in APS design include the maximum sterile hold time, i.e., duration from the end of sterilization to use of lyophilizer, and the maximum hold time from filtration to lyophilization.
Some examples of worst-case challenges are also mentioned. These include loading the largest number of trays, and the maximum duration of chamber door opening where the chamber interior is exposed to the clean-room environment.
An important requirement in the new Annex 1 is 8.123. “Lyophilizers and associated product transfer and loading/unloading areas should be designed to minimize operator intervention as far as possible. The frequency of lyophilizer sterilization should be determined based on the design and risks related to system contamination during use. Lyophilizers that are manually loaded or unloaded with no barrier technology separation should be sterilized before each load. For lyophilizers loaded and unloaded by automated systems or protected by closed barrier systems, the frequency of sterilization should be justified and documented as part of the CCS [Contamination Control Strategy].”
This requirement seems to indicate a preference for automated loading and unloading, and/or with the loading/unloading equipment protected with barrier isolation, under which situations the frequency of lyophilizer sterilization can be justified and documented, as opposed to manual loading/unloading situations where the lyophilizers must be sterilized before each use. The additional delay permitted for the introduction of this requirement (25 August 2024) seems to indicate that mechanical modification within the clean room and re-validation via media simulation is expected (which may be incorporated during an annual shutdown).
Interventions
Assessing the contamination risk of various types of interventions is an important objective of APS. The new Annex 1 now requires the inclusion of various aseptic manipulations, interventions, and other worst-case scenarios in APS. Aseptic manipulations must include the aseptic setup of the filling machine. The key consideration here is to simulate interventions occurring during the routine aseptic process as closely as possible during APS. An appropriate practice would be to review all interventions occurring during processing, e.g., every six months or each year, and add any new interventions into the APS Protocol. Similar interventions may be grouped, and worst-case conditions must be selected/justified in the APS protocol. The new Annex 1 also mentions frequency, which means if an intervention occurs frequently such as topping up a stopper bowl, then it should be performed at a similar frequency during APS; changing filling needles is not performed regularly, so its frequency in APS should be less than topping up the stopper bowl. The inclusion and frequency of interventions should also be based on risk assessment - higher-risk interventions that pose risks to the sterility of products must be included and performed.
Paragraph 9.35 states, “APS should not be used to justify practices that pose unnecessary contamination risks.” This point has been mentioned numerous times in the past by various regulators and Quality Assurance groups. It is not justifiable to include interventions in the APS that may increase the risk of contamination, in an attempt to validate such practices. An example would be the opening of a Restricted Access Barrier System (RABS) to perform major repair work.
Considerations for the APS Plan
In the new Annex 1, thorough details are provided to develop the APS plan, and the following considerations are explored:
1. Identification of worst-case conditions and variables for APS. An assessment needs to be performed to identify and select process variables and worst-case conditions based on the impact to the process. An example of a worst-case condition would be the vial size with the largest opening of the vials, where the exposure to the environment is maximum. Slowest line speed also presents a higher risk as the vials are exposed to the environment for the longest duration.
2. Bracketing or matrix approach can be used for various container/closure combinations for the same or different products if process equivalence is scientifically justified. The matrix approach is acceptable for a range of product/container sizes. For example, the largest (longest time to fill) and smallest (fastest speed of filling machine) containers should be included in the APS protocol, together with an intermediate container size/filling speed if there are more than three product/ container sizes in the matrix.
3. Maximum hold time for products and equipment during the APS. Supplementary microbiological testing of items such as wrapped sterilized containers, or wrapped sterilized filling machine components should be used to support maximum holding times of containers or equipment (as stated in the batch record or production SOP).
4. The media fill volume in the container should be sufficient to contact all the interior surfaces that could potentially be the site of contamination in the sterile product. Additionally, there needs to be sufficient headspace in the filled container to support potential microbial growth.
5. Inert gas used in routine operation should be substituted with equivalent flow of air to support microbial growth. An exception is when detection of anaerobic microorganisms is intended.
6. The nutrient media selected should be capable of growing a group of reference microorganisms stated in pharmacopeia, for example USP, and growth promotion testing of such microorganisms needs to be confirmed for the media batches used. The array of microorganisms should also include representative local microorganism isolates.
7. The detection methods for environmental microbial contamination should be reliable and validated. Common methods are active air sampling, contact plates, and settle plates. The contact plates typically need to incorporate an agent to neutralize disinfectant residues.
8. The APS should be of sufficient duration to challenge the entire process, and include all necessary operators, all interventions, shift changes and the capability of the operational environment to produce a sterile product. For example, if the media fill batch size is to be smaller than routine batch size, the filling may be divided into sections, and the line may be paused temporarily in between the filling sections to achieve the desired overall APS duration.
9. Filling operation shifts that extend or change personnel must capture operator fatigue and include the shift changeover(s) as shift changeover involves the entry of new personnel and increased activities in the room. The APS should be designed to capture factors that pose a risk to product sterility and qualify the maximum time the operators can work in the cleanroom.
10. Interventions done when the process is idle such as shift changeover, recharging dispensing vessels, introduction of additional equipment etc., should be included in APS.
11. Environmental monitoring is to be performed for the entire duration of APS, as required for routine production.
12. For campaign manufacturing, APS batches are to be performed at the beginning and at the end of each campaign to simulate contamination risks during the campaign run. The objective is to demonstrate that the campaign duration does not pose any risk to the product.
13. Routine APS is required, but “End of production APS” may be used for additional investigative purposes if justification is provided. If used, it must be demonstrated that the product residue does not inhibit microbial growth.
For sterile active substance preparation, the media batch size should be large enough to represent routine operation and sufficient to simulate worst-case interventions. Simulated materials such as surrogate materials or growth media are to be subjected to microbial growth evaluation. The surrogate material selected should be similar in physical characteristics and rheological properties to the material it is to replace in the APS. Additionally, the most important selection criteria is that the surrogate material should not jeopardize the recovery of microorganisms, i.e., should not be bactericidal or bacteriostatic to the positive growth control organisms when suspended in the APS medium.
Similar to the previous version of Annex 1, the new Annex 1 states that APS is required for initial validation of a sterile facility, and also after significant modification of facilities, operational practices, and services or equipment that may have an impact on the sterility assurance of the product. The initial requirement is three successful consecutive batches of APS, and subsequently, six monthly periodic revalidation batches for each aseptic process, filling line, and shift. The new Annex 1 offers that all operators should participate in at least one successful APS annually. It is also recommended to perform an APS before line shutdown or long period of inactivity, to demonstrate that the batches made before the planned shutdown/period of inactivity did not have contamination issues during processing.
As small-scale manual aseptic compounding and filling processes have a higher risk of contamination than an automated process, the qualification requirements for operators are more stringent. It is expected that each operator should take part in three successful consecutive initial APS batches, followed by revalidation by participation in one successful APS approximately every six months. This is commensurate with the higher level of risk associated with manual aseptic filling processes. Again, the APS batch size needs to mimic the actual manual filling production operation, and also in this case, all the container sizes and equipment train need to be included in APS.
In the new Annex 1, the batch size requirement is unchanged. The typical number of units to be filled is a minimum of 5000 to 10,000 units. For batch sizes that are smaller than 5000 units, the number of containers filled should be at least equal to the production batch size and should be sufficient to simulate all the activities and interventions in the aseptic filling process.
Incubation and Assessment of Results
Filled APS containers should be agitated, swirled, or inverted before incubation to ensure contact with the media with all interior surfaces in the container. The number of reject containers during the APS batch should not be more than the number of rejects during routine production batches including, for example, those containers that are rejected during the start-up of filling. All integral containers should be incubated, including those with cosmetic defects and those that have undergone non-destructive in-process control checks.
Where processes include materials that contact the product contact surfaces but are then discarded (e.g., product flushes), the discarded material should be simulated with nutrient media and be incubated as part of the APS.
Clear containers should be used in APS to facilitate the inspection of media for turbidity during incubation - opaque containers may be substituted with clear containers of the same configuration. In the case where such substitution is not possible, a suitable method of detection of microbial contamination should be developed. Microorganisms isolated from contaminated containers in APS must be identified to the species level to help in the investigation and identification of the root cause of the contamination source.
Filled media containers should be incubated with minimum delay (the limit should be stated in the protocol). The incubation conditions and duration must be scientifically justified and validated to provide an appropriate level of assurance of recovery of contaminating microorganisms. This is typically seven days at 20 - 25˚C, followed by seven more days at 30 - 35˚C.
Only trained and qualified personnel may perform the inspection of incubated containers for any sign of microbial contamination. Positive control tests should be performed on sterile (no growth) samples of the filled containers at the end of incubation, using compendial reference strains of microorganisms or local isolates.
The target for media fill is still zero contaminated units, but in the new Annex 1 revision the investigation and revalidation strategy based on batch sizes and number of contaminated units (stated in the previous version) has been removed. Any contaminated unit is now to be regarded as a failed APS, and an investigation to determine the most probable root cause of the contamination, appropriate corrective actions, and revalidation of APS is expected. In addition, the company is also expected to quarantine any product batches manufactured, pending the outcome of the investigation. If the root cause is determined to be due to operator error, re-training and re-qualification of the operators is required. Production can resume only after the completion of the investigation and the revalidation of the aseptic process by successful further APS batches.
The APS Batch records should contain records of details such as reconciliation of container numbers, start and end times of batches, interventions and process pauses, and the initials of the operators involved in the interventions. Justification for filled and non-incubated units and all microbial data should be recorded in the batch record.
The new version of Annex 1 also includes paragraph 9.48, “An APS run should be aborted only under circumstances in which written procedures require commercial lots to be equally handled.” Criteria for stopping or aborting production batches should be defined in production and/or quality documentation, and APS batches should only be stopped or aborted by the same criteria. An investigation should be documented in all such cases.
When an aseptic process has not been in operation for an extended period, a repeat of the initial three APS batches is required before continuing manufacture. A repeat of the initial APS is also required if there is a change to the process, equipment, procedures, or environment that has the potential to impact the sterility assurance of the process or products, or if there are changes in the containers or container closure combinations.
Conclusion
From our review of the new EU Annex 1 “Manufacture of Sterile Medicinal Products,” there are more requirements related to Aseptic Process Simulation (APS) than in the previous version. Details previously available in related guidance documents have now been incorporated into the new GMP Rules.
More specific details of APS may be referenced in our articles published in 20222,3 and references therein; many points covered in these articles are relevant to the new EU Annex 1.
References
1. European Commission, Brussels. “The Rules Governing Medicinal Products in the European Union, Volume 4 EU Guidelines for Good Manufacturing Practice for Medicinal Products for Human and Veterinary Use”; Annex 1 “Manufacture of Sterile Medicinal Products”, 2022 August 22, 58 pages (“New EU Annex 1”). (Replaces “Rules Governing Medicinal Products in the EU”, Volume 4 Good Manufacturing Practice; Annex 1 “Manufacture of Sterile Medicinal Products”, 2009).
2. “Validation of Aseptic Processes by Media Filling”, R. Chai and D. Barber, ISPE Pharmaceutical Engineering, 2022 March/April, vol 42 (2) pp.50-57.
3. “Considerations for Validating Aseptic Manufacturing Processes”, R. Chai and D. Barber, A3_La Vague No 74, 2022 July, pp.12-16.
Subscribe to our e-newsletters
Stay up to date with the latest news, articles, and events. Plus, get special
offers from American Pharmaceutical Review delivered to your inbox!
Sign up now!