Sterility Testing of Pharmaceutical Products

 

Sterility Testing of Pharmaceutical Products – Basic Requirements

 

The sterility of a product is defined by the absence of viable and actively multiplying micro-organisms when tested in specified culture media. Turbidity in the broth media usually indicates contamination. This test is performed on the end-product and is one of the quality control tests specified for release of a batch of sterile product. The sterility test cannot be used to demonstrate the sterility of the entire batch but it may assist in identifying a non-sterile batch of product.

Sterility Test - Facilities and Test Requirements

1.Area Sterility testing should be performed under aseptic conditions, which are preferably consistent with the standard of clean room required for the aseptic manufacture of pharmaceutical products.   The sterility test should be conducted within a class A laminar airflow cabinet located within a class B clean room, or in an isolator that need not be located within a controlled environment. The test may also be performed within a class A clean room, if available.

2.Air Supply Air supplied to the environment should be provided through terminal HEPA filters, which should be fitted with audible and/or visual alarms to indicate any sustained, out of specification pressure differentials across the HEPA filters.   There should be a pressure differential of not less than 10 to 15 Pascals (guidance value) between each of the areas, i.e. ambient/airlock and airlock/test room.

3.Air Lock Entry to the clean room should be via an airlock in which operators are required to change into clean room garments.   The airlock should be designed to facilitate movement of the operator between the relatively unclean and clean areas of the room without compromising the aseptic gowning procedure. A step-over bench is a suitable division between these areas.

4.Aseptic Gowning The sterility test operator should change into sterile clean room garments consisting of a one-piece coverall suit, head cover, beard cover (if applicable), overshoes, gloves and mask.

5.Clean room fittings and surfaces ·       All fittings, such as power outlets and light fittings should be flush with the wall or ceiling surfaces and sealed to prevent entrainment of unclean air. Surfaces should be smooth and impervious to the cleaning agents used.   ·       The joints between ceiling/walls/floor should be coved to facilitate cleaning.   ·       If supplied, intercom or communication systems should be designed to allow hands-free use, or their design should facilitate disinfection.   ·       Chairs, storage cabinets and trolleys should be designed to facilitate cleaning and be suitable for use in a clean room environment.   ·       There should be no extraneous equipment within the clean room environment.

6.Cleaning, Sanitisation And Disinfection Outer surfaces of samples and equipment entering the testing suite should be disinfected, preferably with a sporicidal agent. Disinfection of surfaces and sample containers should be carried out in such a way as to avoid adventitious contamination of the samples by the chemical agent.   Surfaces and operators' gloved hands should be disinfected regularly during the test session.

7.Environmental Monitoring Environmental microbiological monitoring should include a combination of air and surface sampling methods, such as: ·       active air sampling; ·       settle (exposure) plates; ·       surface contact (RODAC) plates, swabs or flexible films; ·       operators' gloved hand plates.   Environmental monitoring should be performed under operational (dynamic) conditions either within the isolator or in the laminar airflow and associated background areas.

8. Sterility Test Details   a. Sampling ·       The number of containers tested per batch and quantity tested from each container should be, as a minimum, in accordance with the pharmacopoeial method followed. ·       Samples from aseptic fills should be selected from at least the beginning, middle and end of the batch fill. ·       Samples from terminal sterilisation cycles should be selected from at least the potentially coolest part of the load if such a location was identified during validation studies, and from every load sterilised. ·       If an original test is declared invalid, then any samples used for the repeat sterility test should reflect the original samples in terms of sampling locations or aseptic processing times      b. Test Methodology ·       The test methodology should be in accordance with the pharmacopoeial method used. Membrane filtration of the product, with either an open or a closed system, is the preferred sterility test methodology. Preferably   The filter should be pre-wetted, particularly when small volumes and antibiotics are tested(Filters with pore size of not more than 0.45µ is usually preferred). ·       Filtration of the product should be followed by the minimum number of washes of the membrane with a suitable rinsing fluid established during validation studies. The membrane should not be permitted to dry out between filtration steps. ·       If the product cannot be filtered, then direct inoculation, immersion, in-situ incubation or combination methods as appropriate are acceptable. C.  Media Types ·       The media used should be in accordance with the pharmacopoeial method followed. Soya-bean casein digest (SCD) and fluid thioglycollate media (FTM) should normally be used. d. Incubation Period ·       All test containers should be incubated at specified temperatures for each test media regardless of whether filtration or direct inoculation test methodology is used.   –       At least 14 days incubation –       20-25°C for SCD/TSB, 30-35°C for FTM –       Test containers should be inspected at intervals –       temperatures should be monitored and temperature monitoring devices should be calibrated –       if product produces suspension, flocculation or deposit in media, suitable portions (2-5%) should be transferred to fresh media, after 14 days, and incubated for a further 7 days