Media Fill Validation – Regulatory Approach

Why Media Fill?

During manufacturing of sterile formulations viz. Small Volume Parenteral (SVP), Large Volume Parenteral (LVP), Vaccines and other similar formulations, it is important to ensure that the manufacturing process itself is aseptic. Additionally, it provides another level of assurance that the aseptic environment is being maintained inside the manufacturing area. Hence, it is expected from the manufacturer to prove that the process is aseptic and aseptic environment is being maintained during the entire manufacturing process.

Media Fill Simulation Tests are performed to ensure that the routine commercial manufacturing process produces drug product of desired quality repeatedly and reliably.

What is Media Fill?

Accordingly, the firm has to carry out media fill simulation test which includes carrying out process simulation run by simulating the entire process in order to evaluate and establish the confidence the aseptic processing. Various simulation steps may include but not limited to formulation, filtration, filling and sealing. During Media Fill Simulation the entire production run is carried out using suitable media. Post filling, the vials are incubated for specified duration and are then examined visually for microbial growth.

The media fill simulation test shall include all the possible interventions. The same is explained in detail in subsequent sections.

Who performs Media Fill?

As in routine production, Media Fill Simulation Test also is a joint responsibility of Cross Functional Team comprising of representatives of Production, Quality Control, Quality Assurance, Validation Team, Engineering/ Maintenance

When to perform Media Fill?

Various International Guidelines including PIC/s and ISO have classified media fill tests broadly into two categories. “Start-up” or “Initial Performance Qualification” and “On-going” or “Periodic Performance Qualification”. A third type of qualification is Requalification.

Start-up or Initial Performance Qualification consists of carrying out media fill simulations for each aseptic processing unit operation, for each filling line and for each unique product configuration. It is usually performed for introduction of new facility, new process, new equipment or after critical changes to process and/ or equipment directly in contact with the product. During Start-up Media fill test, three consecutive satisfactory simulation tests per shift has to be carried out before commencement of routine manufacturing activities.

On-going or Periodic Performance Qualification shall be conducted twice annually (approximately every six months) for each aseptic process and filling line. Manufacturer shall choose single filling configuration for each on-going media fill test. The qualification shall include all the activities and interventions which truly represents each shift and shift changeover. It is to ensure that there are no changes to any process or equipment and there were no deviations to the routine operations was observed.

Requalification includes carrying out media fill test which is not scheduled and is often initiated out of any major change to the process or equipment and in case any major deviation is observed in environmental records or other related parameters. Requalification may also be carried in a situation where the manufacturing lines had been idle for more than Six months.

Where to Perform Media Fill?

It is required to be performed as per the conditions that shall simulate as close as possible (if not complete) the routine aseptic manufacturing process. It is mandatory that media fill test should be carried out in the same production area, using same set of equipment being operated by same qualified operators which shall be used during routine manufacturing.

How to perform Media Fill?

Media fill simulation test for sterile liquids is conducted using microbiological growth media in lieu of product.

Every manufacturing firm performs media fill as per their own protocol, but following are the key points that needs to considered and requires clear understanding before finalizing the media fill protocol. Many regulatory guidelines provide their own procedures but it is important to understand that the roots of all are same. Hence, it is advisable to make a comprehensive media fill validation protocol including all the aspects of various guidelines. All the below mentioned key points are the bare minimum requirements which shall be rooted into the media fill validation protocol:

1. Material: The material to be used for media fill test depends on the manufacturing process to be used for the different types of products i.e. liquid, semi-liquid and solid dosage forms: 

• Media: The selection of microbial growth media based on various factors viz. low selectivity, clarity, medium concentration and filterability.

• Low selectivity: The selected media shall have the capability to support the growth of wide range of microorganisms. It shall be able to support the growth of commonly observed microorganisms. The firm shall also identify the isolates during routine environmental monitoring which shall also be made part of the evaluation during media fill test.
• The commonly used media is Soybean Casein Digest Medium (SCDM). Attention shall be paid regarding usage of anaerobic media, in case, where obligate anaerobic organisms have been isolated during routine monitoring.
• The liquid medium shall be prepared in the same vessels and using same manufacturing process as used in routine manufacturing. WFI shall be used to dilute the media. Media may be heated if required for dissolving, but heat provided should be minimal. pH may be adjusted using buffers, but care should be taken that they shall not inhibit the growth of reference microorganisms. The prepared media shall be filtered aseptically into the holding tank as per routine manufacturing process. If justified properly, in certain cases the firm may sterilize the media.
• The prepared medium shall be kept in the sterile holding vessel for the maximum permitted holding time before starting the simulation test. In a case where in routine manufacturing, the bulk solution is stored under refrigerated conditions during the holding time, then the same shall be simulated with the media also.
• Vials and closures should be prepared as in regular production
• The media to be used shall pass the Growth Promotion Test (Both pre and post). The test shall be performed in accordance with the relevant pharmacopoeia and relevant strains of test organisms shall be used.
• The growth promotion inoculum shall be able to support recovery and growth of less than 100 CFU per filled unit.
• The growth promotion ability of media used in media fill test shall be carried out on completion of the incubation period to establish that the media is able to sustain growth if contamination is present. The firm shall demonstrate growth within 5 days of incubation. The incubation temperature shall be same as maintained for simulation test performance.
• For complex processes, special attention should be paid for drawing samples for growth promotion test. The samples drawn shall represent the entire process to ensure that no parts of the manufacturing process alters the growth promoting properties of the medium.

• Clarity: The media used shall be clear enough to allow easy observation of turbidity.
• Medium Concentration: Supplier recommendations shall be referred and followed. In case, manufacturer wants to use different concentration, the same shall be validated to provide equal results before use.
• Filterability: The prepared media shall be filterable through the filter of same grade as to be used in the routine production.

• Glass Vials, Glass Ampoules and Clear plastic vials. In case clear plastic vials are not available for media fill tests the whole contents should be removed for examination. Wherever, clear plastic containers are used for process simulation, it should be noted that the plastic is naturally slightly opaque and thus makes it difficult to observe the contaminated vials that show only a slight haze. Hence, care should be taken to provide sufficient lighting as natural or room lighting shall not be enough to observe clearly.

2. Machine: It is mandatory that media fill test should be carried out in the same production area, using same set of equipment used during routine manufacturing. All the equipment to be used shall be qualified before use. All aseptic holding vessels should be covered by media fill test regularly unless same are qualified periodically by validated, pressure hold or vacuum hold test.

3. Man: In any manufacturing process the common reason for failure is man mistakes. It becomes more critical for the personnel working in aseptic process areas as people are possibly one of the main sources of microorganisms in the area. Hence, it is highly desired that personnel working in the area shall meet following requirements: 

• All the personnel working is aseptic area including operators, supervisor, maintenance, housekeeping, IPQA and Quality Control shall be thoroughly trained on GMP and all other related SOPs. Records of training shall be properly documented.
• All the personnel shall be specifically trained on cleanroom practices and good aseptic techniques.
• Emphasis shall be given on periodic retraining of such individuals so that they keep pace with the current regulatory requirements.
• Personnel involved in environmental monitoring shall be specifically trained on all possible sources of contamination.
• It is highly expected that all the personnel working in aseptic area shall be participating in the on-going process simulation tests at least once a year. The personnel shall be qualified on the basis of participation in media fill simulation test, gowning procedure qualification, Medical records and training on relevant SOPs.
• Effectiveness of training and competence of personnel involved shall be evaluated during media fill simulation tests.
• Filled containers shall be evaluated by the especially trained staff. The visual inspectors shall be appropriately qualified using test kits. They shall undergo routine medical check-up including eye check-up.
• New personnel joining the firm shall participate in at least one successful media fill simulation test before they are permitted to participate in manufacturing operations taking place in critical areas.
• Personnel working in critical areas shall report conditions such as fever, open lesions, cold, cough, diarrhoea etc. as it may affect aseptic work environment.

4. Method: The media fill simulation test shall be similar if not identical to the routine aseptic manufacturing process. All critical manufacturing unit operations shall be thoroughly covered during the test. The detailed key points to be considered while performing the test are as follows:

• Special consideration shall be given to the usage of appropriate combination of container size and opening as well as line speed. The largest containers with the widest mouth, when operated at the lowest line speed is considered as a worst case due to longer exposure to the environment, whereas containers with small diameter e.g. ampoules, when operated at higher line speed may be considered as a worst case due to lack of container stability. Hence, may lead to increased human interventions.
• The media fill simulation test should always represent “worst case” situation and include routine and non-routine interventions during a production run.

Routine intervention: An intervention that is an integral part of aseptic manufacturing process e.g. weight adjustments, shift change, hopper adjustments, sampling, environmental monitoring etc.

Non-Routine Intervention: An intervention that is performed to correct or adjust an aseptic process during its execution. It includes various types of worst-case scenarios to challenge the process under extreme conditions e.g. maximum number of manpower, frequent door opening, power failure, tripping of container, chute jam, vial breakage, longer working hours (operator fatigue), maintenance or breakdown handling etc.

The manufacturer shall prepare a list of routine and non-routine interventions.

• Fill volume shall be sufficient enough to wet all the container-closure seal surfaces when the container is swirled or inverted. It should provide enough head space to ensure capability of microbial growth and to ensure detection of turbidity.
• The firm may implement bracketing approach in case multiple sizes of same container/closure configuration are used. Post initial qualification, each configuration shall be used in on-going media fill simulation tests. If there are more number of configurations, matrixing approach may be used. However, it is highly recommended that all the vials used for routine production shall be rotated at least once a year.
• The media fill simulation tests shall be carried out in conjunction with comprehensive environmental monitoring programme.
• If the products are routinely manufactured using inert gas, the same shall be replaced with sterile filtered air as it may hamper microbial growth.
• All the filled units shall be properly labelled individually or group-wise.
• Media fill simulation tests shall be performed for the maximum filling time duration. In case its not possible simulation runs shall be long enough to cover all types of manipulations and interventions. If any process involves filling operation to be continued for more than 24 hours, the media fill simulation test should extend over the whole of the standard filling period. In order to prevent filling of excessively high numbers of containers, manufacturer may run the machine for a reasonable time. Care should be taken that the validity of the simulation is not diminished by this procedure.
• In cases where the number of containers filled are less than 3000, the minimum number of containers processed shall be equal to the commercial batch size.
• Simulation studies shall be carried out on different days of the week and at different time of the day and not only at the start of a day.
• It is also advisable to video tape the entire media fill simulation test in order to investigate in case of a possible failure. It also provides authenticity of the test being carried out.
• The containers before incubation shall be inverted, agitated, swirled and are in other terms manipulated to ensure that the media comes in contact with all the internal surfaces of the container and closure.
• There shall be enough head space in the filled vials in order to provide requisite oxygen for the growth of obligate aerobes. In case, anaerobes are observed during environmental monitoring, the head space may be filled with the inert gas as it will support the growth of anaerobes.
• All the filled containers which on visual inspection were observed to be leaking, broken or otherwise damaged shall be recorded and removed. However, containers with cosmetic defects, non-destructive weight checks and all other containers shall be identified and incubated together.
• The filled containers shall be incubated at 20-25°C for a minimum of 7 days followed immediately, or after a first reading, by incubation at 30-35°C for a total minimum incubation time of 14 days. For the first seven days the containers shall be in upright position and for next seven days they shall be in inverted position.
• After completion of the incubation period, all the incubated containers shall be thoroughly inspected for possible microbial growth. A control container shall also be provided to all the trained observers, to compare the contaminated vial.
• The microorganism if found in any of the container shall be identified upto genus level but preferably to the level of species to aid in the determination of likely source of the contamination.

5. Measurement: After completion of the incubation period, all the filed containers are taken out for evaluation. Contaminated containers with damage to its container/closure may not be considered as a failure as the damage will compromise the integrity of the packaging system. For smaller batches number of containers filled shall be at least equal to the commercial batch sizes. However, care should be taken that all the interventions shall be covered and if required more number of containers shall be filled.

For evaluation purpose following table may be referred:

Important Considerations: 

1. In case of any failure of media fill simulation test, then all the batches manufactured since the last successful media fill test shall be reassessed. The requirement of the assessment is based on the outcome of root cause analysis for the deviation happened during the media fill simulation test.
2. During media fill simulation test special care shall be given to include environmental and personnel monitoring.
3. During media fill simulation test special concentration shall be given to the documentation. Detailed Batch records, reconciliation records, testing records etc. shall be maintained.
4. In case any batches are manufactured after media fill simulation test and before the conclusion of media fill test report, the same shall be placed under quarantine.
5. It shall be noted that each simulation test is unique in itself and hence, it is not possible to extrapolate these results directly to actual production contamination rates.
6. Process simulation is not intended to validate product sterilization.

References: 

1. Aseptic processing of health care products – Part 1: General requirements (ISO 13408-1:2008)
2. PIC/S Validation of Aseptic processes (PI007-06)
3. WHO Technical Report Series no. 961
4. EU Guidelines to Good Manufacturing Practice Medicinal Products for Human and Veterinary Use; Volume 4, Manufacture of Sterile Medicinal Products, Annexure 1
5. Schedule M, Part I-A of Drugs and Cosmetics Act