Media Fill Validation Test in Sterile Pharmaceutical

In the pharmaceutical industry, the product quality is directly dependent on aseptic conditions maintained in manufacturing area. Media fill validation test is the fundamental requirement for validation of aseptic processing. For regulatory agencies like USFDA, EMA and WHO media fill studies are mandatory to demonstrate that aseptic process is capable of consistently producing sterile products without any contamination.

This article has an overview of media fill tests, including their purpose, methodology, regulatory expectations, best practices and common issues found during sterile manufacturing.

What is Media Fill Validation Test?

To validate sterile manufacturing process, a media field simulation study is conducted that validates the aseptic process. A nutrient growth medium like soybean casein digest medium is used instead of actual drug product. These filled containers are then incubated to detect microbial contamination in the sterile manufacturing process.

The principle of media fill validation is simple; if media fill process is performed correctly and contamination control measures are effective then media fill units will remain sterile after incubation. If any microbial growth is found in media-filled units, then it indicates a breach in sterility in process.

Why is Media Fill Validation Important?

The primary objective of media fill validation is to provide assurance that sterile manufacturing system performs consistently without any microbial contamination. It has following importance.
1. Regulatory Compliance: Regulatory agencies like FDA and EMA require aseptic process validation using media fill tests.
2. Sterility Assurance: It ensures that sterile products can be manufactured under routine operating conditions without any contamination.
3. Process Simulation: Media fill validation replicates real manufacturing conditions including interventions, equipment setup and personnel activities, so it produces real results like product manufacturing.
4. Risk Mitigation: Media fill validation helps to identify weak points in aseptic processing such as poor gowning practice, operator errors or equipment design problems.

Regulatory Guidelines for Media Fill Validation

Several international regulatory agencies define requirements for media fill validation.
US-FDA Guidance for Industry - Sterile Drug Products Produced by Aseptic Processing
EU-GMP Annex 1 - Manufacture of Sterile Medicinal Products
WHO Technical Report Series - TRS 961, Annex 6
PIC/S Guidelines - PE 009-14 Annex 1

Some key expectations include:

• Media fills must be done in most challenging and worst-case scenarios.
• Test should be repeated at a defined interval, usually 6-12 months.
• Planned and unplanned interventions must be incorporated into the simulation.
• Batch size of simulation test must reflect the actual batch size.
• Minimum 5000 to 10,000 units are recommended for commercial production.

Steps in Conducting Media Fill Validation

Prerequisites

1. Approved Soybean casein digest broth.
2. Aseptic area gowning procedures and Entry into sterile areas.
3. Environmental Monitoring of manufacturing areas by Plate Exposure, Air sampling and surface monitoring procedures and its SOP’s. Personnel Monitoring by Finger DabSwab Test Method & its SOPs.
4. Qualified and validated manufacturing equipment, system facility (i.e. HVAC, water, compressed gases) CIP and SIP procedures.
5. Trained operating personnel’s.
6. Approved BMR for media fill trial.

Equipment/System Description

Location: Manufacturing Area ( Mixing room and filling room)
Equipment: Mixing Tank, Holding Tank, Filtration housings, connected product line and FFS machines

Identification of Critical Control Monitoring Parameters

Critical control parameters were identified and it should be considered and recorded during validation program, following are the critical points-

• Check all the equipment and system facility is validated.
• Check and ensure that the HVAC system, compressed air, CIP and SIP procedures are qualified.
• Check and ensure that all operations, cleaning/ sanitization procedures are established and operating personnel are trained.
• Check the Media used for Process Simulation is passed for GPT
• Check and ensure that the WFI used for the preparation of batch is compiled to USP/IP

Environmental monitoring should cover three operational shifts, by following methods –

• Settle plate method
• Air sampling
• Swab testing
• And Personnel monitoring

Study Design

Worst Case Consideration

1. Allowed maximum number of personnel in the Aseptic Processing Area, including the maintenance and housekeeping personnel
2. Simulating routine machine parts assembling/ disassembling, equipment/ system setups, in between minor maintenance jobs
3. Increased the time period to start the filling operation
4. Duration of the media fill trial was more than that required for the routine manufacturing operation.
5. Simulating Process / Power breakdown during the process simulation test
6. Shift changes and breaks

Frequency, Duration and Number of runs

1. Media fill trials must be performed on a semi-annual basis for each aseptic process and additional media fill trials should be performed in case of any change in procedure, practices or equipment configuration.
2. Filled units in Media Fill run should be 10,000 units or more. Fill minimum 3000 units in each production shift.
3. The duration of Media Fill run must cover all the three operational shifts in each run turn by turn including worst cases.
4. Fill volume for Media Fill run for LVP is 60 ml.

Environmental Consideration

1. Cleaning of Area must be done by using routine cleaning agent and disinfectant solution, as per latest SOP
2. Microbiological Environmental monitoring should be carried out to cover the entire media fill program for manufacturing area by Settle plate, Active Air sampling, Swab test and personnel monitoring as per the latest SOP.

Media

1. Soybean Casein Digest Medium, manufactured by Hi-Media Laboratories should be used for Media fill trial.
2. The media must be passed the test for GPT to promote the growth of gram-negative and gram-positive bacteria and yeast and molds.

Incubation and examination of filled units

1. Incubate all media filled units in normal position after leak test at of 20 to 25deg.C for 7 days. Incubation temperature should be maintained within 22.5 ± 2.5deg.C.
2. After completion of 7 days Incubation at 20 to 25deg.C, invert the units and incubate them at 30-35deg.C for next 7 days. Incubation temperature should be maintained within 32.5±2.5deg.C .
3. Each media filled unit should be examined by trained Microbiologist after 3rd day, 7th day, 10th day and 14th day.
4. All suspect units identified during the observation should be brought to the immediate attention of the QC Microbiologist.

Interpretation of Test Result

1. Any contaminated unit should be considered objectionable and investigated. The microorganism should be identified to species level.
2. The investigation should survey the possible causes of contamination. 
3. When filled units up to 10000, one contaminated unit should result in an investigation, including consideration of a repeat media fill.

Validation Procedure

CIP and SIP for LVP line

1. Carry out the cleaning of LVP mixing tank and holding tank along with product line and bottle pack machine 360 as per SOP for CIP.
2. At the end of cleaning, collect last rinses sample from sampling point and send to QC department with written information for testing of previous product traces.
3. After getting approval report from QC, affix a status label on the tank “READY FOR STERILIZATION”.
4. Immediately carry out the sterilization of LVP holding tank along with final filter and product line of bottle packaging machine as per its respective SOP.
5. After Sterilization, affix a status label on the LVP line.

Dispensing of Soybean Casein Digest Medium for 750 L batch size

1. Give raw material requisition slip in duplicate to store (either computerized or manual) duly signed by Production Officer and Authorized by HOD (Production)
2. Enter to dispensing room as per SOP for entry-exit procedure to dispensing area.
3. Check for the clearance of the area from any unwanted materials. Check for the cleanliness of the area, LAF, weighing pan as per checklist. Put “ON” the reverse LAF unit 15 minutes before dispensing of material.
4. Check the availability of clean containers, SS scoops, pressure differentials, and temperature & humidity should be not more than 25deg.C and 45 to 60% RH respectively.
5. Check the balance spirit level is within the circle and then calibrate the balance as per Balance Calibration SOP.
6. Take the Approved Soybean Casein Digest Medium in pre-dispensing room, place on SS pallet and check the label of the container for correctness and Approval of material.
7. Transfer the material to the dispensing room, place the empty clean container on the balance and record the tare weight. Press “ZERO” of the balance and weigh the required quantity of material, note the weighed material and then remove the container from balance and press Zero.
8. Close the dispensed material, affix the weighing tag and transfer the material in the dispensed material storage room. 
9. After dispensing, put “OFF” the balance and LAF. Clean the surrounding area, balance and spray with 70% IPA solution.
10. Reseal the original container and shift to their original place.

Batch Preparation 750 L

1. Ensure that the area and product line is clean and free from the traces of previous product.
2. Recheck the tag and gross weight of Soybean casein digest medium (SCDM) to be used for manufacturing and ensure that they match as per entries made in the BMR weighing sheet.
3. Check the status board affixed to the tank “READY FOR USE”, also verify the records and ensure that the bottom outlet valve of the mixing tank is closed.
4. Send the entry point sample of WFI from the user point to QC department for testing along with BMR.
5. On approval of WFI sample from QC department, affix a status board on the Mixing tank “UNDER MANUFACTURING” with Product name and B. No.
6. Collect approx 200 L water for injection at 80 to 85deg.C in a manufacturing tank fitted with a stirrer.
7. Start the stirrer and add SCDM through the main hole of the tank.
8. Continue stirrer for complete dissolution of ingredients.
9. Stop the stirrer.
10. Make up the volume to the 750 L with water for injection.
11. Start the stirring for complete dissolution of SCDM and homogeneous bulk solution (generally required 10 minutes).
12. Collect the sample of bulk solution in a sterile sampling bottle and send it to QC for testing of color clarity, pH and bioburden along with bulk intimation slip.
13. After getting clearance of bulk analysis from Quality Control, start the filtration from mixing tank to Holding tank with the help of pump as per its respective SOP.
14. Perform the bubble point test of the final filter after holding tank as per Bubble point test SOP.

Filling And Sealing

1. Start the filtration from holding the tank to FFS machine using the pump.
2. Drain one buffer tank approx 1.3 liters of bulk solution from filling nozzle to eliminate any possibility of dilution of bulk by condensates in the product line of the machine post SIP.
3. Check online cartridge filter integrity test.
4. Start Machine and discard initial 10 shots.
5. Collect the first cassette of vials from next shot and send the sample with written information to QC for testing.
6. Arrange the out coming cassettes of vials sequentially in vacuum chamber tray and verify the results of testing from QC department.
7. Now start the filling and sealing continuously as per SOP for Filling and sealing.
8. Collect the filled and sealed containers coming out of the filling area in plastic crates.
9. During filling operation keep the filled vials separately for each breakdown, shift change, power breakdown, stoppage etc and assign lot number. 
10. Carry out the leak test.
11. After leak test, transfer the goods vials in the clean plastic crates horizontally in the cassette from one above the other, lot wise separately.

Related: Buffer Area and Its Maintenance in Sterile Manufacturing Facility

Incubation and Examination of Media Filled Units

1. Incubate all media filled units in normal position after leak test at 20 to 25deg.C for 7 days. Incubation temperature should be maintained within 22.5 ± 2.5deg.C .
2. After completion of 7 days Incubation at 20 to 25deg.C, invert the units and incubate them at 30-35deg.C for next 7 days. Incubation temperature should be maintained within 32.5±2.5deg.C .
3. Each media filled unit should be examined by trained Microbiologist after 3rd day, 7th day, 10th day and 14th day.
4. All suspect units identified during the observation should be brought to the immediate attention of the QC Microbiologist.
5. During incubation, if any unit found to be damaged should be recorded in media fill observation format.

Interpretation of Results

1. When filling fewer than 5,000 units, no contaminated units should be detected.
2. When filling 5,000 to 1,0000 units:
a. One contaminated unit should result in an investigation, including consideration of a repeat media fill.
b. Two contaminated units are considered cause for revalidation, following the investigation.
3. When filling more than 10,000 units:
a. One contaminated unit should result in an investigation;
b. Two contaminated units are considered cause for revalidation, following the investigation.

Failure Investigation

1. Any contaminated unit should be considered objectionable and investigated. The microorganism should be identified to species level.
2. The investigation should survey the possible causes of contamination during media fill trials i.e. Environmental, personnel and surface monitoring.
3. Based on the outcome of the investigation, assign the cause of failure is assignable or not assignable.
4. If the cause is assignable, then take a corrective and preventive action and record the same in suitable format.
5. If the cause is not assignable, then the process should be validated, as it is a new process. Consecutive three-process simulation test should be performed to demonstrate consistency and reliability on the sterile formulation manufacturing process to produce an acceptable product.

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