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Sterility Testing Procedure

Learn how to perform the test for sterility for sterile pharmaceutical products by Membrane Filtration Method.

1.0  Equipment Required

       Manifold holder assembly
       Vacuum pump.

2.0  Material Required

       Sterile 0.45µ Membrane filter
       Sterile FTM
       Sterile SCDM
       Sterile 0.1% w/v Peptone water.
       70% sterile IPA Solution.
       Gas burner
       Sterile Filtration assembly
       Sterile SCDA plates
       Sterile Swab

3.0  Utilities Required

       Vacuum Pump

4.0  Procedure:

4.1  Membrane Filtration Method

4.1.1  Sample for Finished Products: Collect the samples to be tested for sterility as per SOP. Out of the whole sample, randomly select 20 articles (as per Pharmacopoeia) of each lot of batch for both LVP and SVP terminally sterilized products and for aseptic filled products.
4.1.2  Sample for Intermediates: Randomly collect 16 pre-sterilized bottle samples to be tested for sterility from LVP bottle pack machine (When change over the new Product collect the 16 bottle samples of Ist batch ) separately in such a way that each bottle should represent each cavity of the mould of bottle pack machine. 
4.1.3  Transfer the samples to QC department in clean plastic crates.
4.1.4  Wipe the sample article individually with 70% IPA solution and keep in a clean S.S trays marked with Product Name, Batch No and Lot No, and then transfer the samples to the sterility room through clean pass box for performing sterility.
4.1.5  Prepare the media tubes (FTM and SCDM) as per the SOP for preparation of culture media, dispense 100-100 ml quantity in test tubes & plug them. Sterilize both the media at 121ºC and 15 psi pressure for 20 minutes as per SOP for Media Sterilization by Autoclaving.
4.1.6  After autoclaving Label the tubes with Name of Media, Media Batch No. and pre-incubate the media tubes at appropriate temperature i.e. SCDM tubes at 20 to 25ºC whereas FTGM tubes at 30 to 35ºC for 24 - 48 hrs before subjecting them for sterility operations.
4.1.7  Autoclave Dress, S.S. cups, Receptacle unit, Scissors and forceps in a stainless steel container at 121ºC temperature and 15psi pressure for 30 minutes as per SOP.
4.1.8  After Sterilization cool the contents and aseptically transfer in a S.S. container to cleaned Pass box.  Transfer the pre incubated sterile media tubes, SCDA plates, sterile swabs, sterilized manifold, and 0.1% w/v peptone water to the sterility test room through pass box.
4.1.10  Enter in sterility room as per the SOP for Entry / Exit procedure for Sterility Room.
4.1.11  Start the LAF as per SOP for operating instruction for LAF.
4.1.12  Wipe out all samples to be tested for sterility with 70% IPA solution.
4.1.13  Before starting sterility test, expose the SCDA plates as specified locations throughout the testing as per SOP.
4.1.14  Connect the Filtration manifold holder assembly with the S.S. reservoir properly with pipe and place sterilized S.S. cups in the sterile receptacle under Laminar airflow unit. Check the Manometer reading of working LAF and check the temperature as well as humidity of the sterility room
4.1.15  Manometer reading of working LAF chamber pressure should be between 08 – 15mm of WG. Temperature reading of the sterility room should be 27ºC ± 2ºC.
4.1.16  Switch ON the vacuum pump but close the vacuum of the manifold holder assembly with the help of vacuum control key, present on the base of individual manifold holder. Now place 0.45m sterile membrane filters between filtration cup and receptacle with the help of sterilized forceps.
4.1.17  Wet the membrane filter by adding approx 15 ml of sterilized Fluid A (0.1% peptone water) to filter holder, and filter the fluid by employing vacuum.
4.1.18  Cut the tip of bottle/vial or ampoule with sterile SS blade in front of the gas burner and immediately transfer not less than half of the contents for LVP and whole content of the vial for SVP to membrane.
4.1.19  Immediately filter the solution with the aid of vacuum and wash the membrane three times with 100 ml of sterilized fluid A (Washing with fluid A is not required in case of sterile water for injection).
4.1.20  After complete filtration, stop the vacuum of manifold with the help of manifold vacuum control key.
4.1.21  Lift the membrane carefully with the help of sterile forceps, aseptically cut the membrane filter into two halves with sterile SS scissor and transfer one half to FTM and one half to SCDM tubes by unplugging in front of gas burner only.
4.1.22  Label both the tubes with product name, B. No, lot No., date of testing, Completion date & Tested by.
4.1.23  Simultaneously prepare a negative control by filtering 100 ml of 0.1% peptone water instead of product sample, cut the membrane into two halves with sterile SS scissor and transfer one half to FTM and one half to SCDM and label both the tubes as Negative control.
4.1.24  Simultaneously prepare a chamber control during the sterility take two tubes, one is SCDM & other one is FTM tube, unplug the cotton plug of the tube and expose in LAF during sterility, after completion of sterility re-plug the tubes and then incubate the tubes as a chamber control.
4.1.25  After completion of work transfer all inoculated media through hatch box and then transfers all the equipment and exposed plates to microbiology analysis section.
4.1.26  Immediately move from the sterility area as per exit procedure specified SOP for  Entry Exit Procedure for Sterility Room.
4.1.27  Incubate the FTM tubes at 30ºC – 35ºC and SCDM tubes at 20ºC – 25ºC for 14 days. 
Incubation period for terminally sterilized products is not less than 7 days and 14 days for aseptically filled products as per IP. If the Product is as per USP, BP, incubation period is 14 days for both terminally sterilized as well as for aseptically filled products.
4.1.28  Start the LAF of Microbiology Analysis room as per SOP and prepare four positive Control tubes by inoculating aseptically 10 to 100 cfu in FTM tubes with S. aureus NCIM 2079, P. aeruginosa NCIM 2200, B. subtilis NCIM 2063  and environmental flora EF - 1. Similarly prepare three SCDM positive control by inoculating approx 10 to 100 cells separately with C. albicans NCIM 3471,  A. niger NCIM 1196 and environmental flora EF - 2. Incubate FTM positive control tubes at 30 – 35ºC for 3 days & SCDM positive control tubes at 20 – 25ºC for 5 days.

Related: Incubation Conditions for Common Media used for Fungus and Bacteria

4.2  Observation and Interpretation of Results

4.2.1  Visually examine the media tubes daily to its conclusion for macroscopic evidence of microbial growth.
4.2.2  If no evidence of growth observed in any of the tube the product to be examined for the test complies with the test for sterility.
4.2.3  The test is not valid unless the negative control shows negative till at end of incubation, and positive control shows growth within specified incubation period.
4.2.4  Destroy all the positive controls after confirmation of growth in both FTM and SCDM tubes (Generally growth will observed in 24 to 48 hrs).
4.2.5  If evidence of microbial growth is found in any of the tube, investigate the cause of its failure as per SOP for sterility test failure investigation. If investigation report concludes that test is invalid, repeat the test with 20 units.
4.2.6  If no evidence of growth is found in the repeat test the product examined complies with the test for sterility. If evidence of microbial growth is found in the repeat test the product examined does not comply with the test for sterility.

Related: Incubation of Petridishes in Inverted Position

5.0  Precaution

5.1  Sample bottles / vials should be wiped properly with filtered 70% IPA before transferring them to sterility room and also inside the sterility room before sterility operations. Hatch box should also be cleaned properly with filtered 70% IPA solution.
5.2  Any material used in the sterility operation or inside sterility room should be autoclaved properly.
5.3  The tip of sample bottles / vials should be heated properly in front of gas burner before cutting with sterile heated cutting blade.
5.4  Clean the waste solution reservoir immediately after sterility operations and mop the outer surface of the reservoir with filtered 70% IPA with sterile mopper.

6.0  Frequencies

       For LVP – Lot wise
       For SVP – Batch wise

7.0  Abbreviation

       SOP    :     Standard Operating Procedure
       IPA     :      Isopropyl Alcohol
       SVP    :      Small volume Parenterals
       LVP    :      Large volume Parenterals
       FTM   :      Fluid Thioglycollate Medium
       SCDM :     Soybean casein digest medium
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
Email: .moc.enilediugamrahp@ofni Need Help: Ask Question

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