ASTM E3251-23 PDF

SIGNIFICANCE AND USE 4.1 Single-use systems (SUSs) used for biopharmaceutical manufacturing must maintain sterility and product quality of the fluid inside. Such articles or systems should therefore be validated as providing an effective barrier against microbial ingress. The microbial barrier properties of a SUS may be demonstrated using deterministic physical tests that have been correlated to microbial integrity. Such physical test methods are described in Test Method E3336. Two microbial test methods (aerosol exposure and immersion exposure) are described in this test method that can be used to demonstrate microbial integrity of a SUS or determine the MALL, the maximum defect size that does not allow microbial ingress, into a SUS. 4.2 It is important to note that the results of microbial ingress tests are heavily dependent on the conditions under which the test is performed and are not suitable for routine checking of a SUS due to the test’s destructive nature. 4.2.1 Any size defect may be forced to fail under sufficiently aggressive conditions (including a large enough sample size, high differential pressure, or high hydrostatic pressure, for example) that would not ordinarily reflect normal use conditions. Thus, it is necessary to clearly define the relevant conditions for a test through a risk assessment of both the actual SUS claims and its final use (Practice E3244). Once that is established, the size of defect that can be detected under those conditions can be determined, if required, using defined defects. 4.2.2 “Relevant conditions” refers to worse-case actual use conditions but does not mean that a SUS must be tested under theoretically absolute (extreme) “worst-case” conditions. 4.2.3 Testing may be performed on individual components or entire systems. Considerations for defining “relevant conditions” and testing design should be based on a risk assessment for the SUS intended use and should include: 4.2.3.1 A channel created by a defect or breach through the... SCOPE 1.1 The microbial test method outlined in this test method applies to microbial ingress risk assessment of a single-use system (SUS) or its individual components that require integrity testing either by the assembly supplier or the end user of the assembly based on a potential risk of a breach to the product or manufacturing process. 1.2 The aim of microbial ingress testing of sterile SUSs used in biopharmaceutical manufacturing is two-fold: 1.2.1 Firstly, it is used to evaluate the ability of a SUS fluid path to remain sterile after a SUS has been challenged by microbial exposure. Microbial exposure is achieved either by directly placing a SUS into a container of microbial challenge solution, or by delivering an aerosolized microbial challenge onto a SUS that is placed inside a test chamber designed to generate and deliver the aerosol. The choice of the test challenge organism should be justified based on a risk assessment of the SUS and conditions of use. 1.2.2 Additionally, microbial ingress testing can be used to determine the maximum allowable leakage limit (MALL) that does not allow microbial ingress under specific test conditions. The defect size that can be detected by specific physical integrity testing methods (see Test Method E3336) can be correlated to this MALL in order to claim microbial integrity. Test articles bearing calibrated defects over a range of dimensions, including up to a defect size expected to consistently allow microbial ingress as a positive control (defect-based positive control), may be tested to determine the MALL. 1.3 Both purposes for microbial ingress testing as described in 1.2.1 and 1.2.2 can either be conducted by liquid immersion or aerosol exposure. For the purpose described in 1.2.2, the type of exposure should be determined according to the SUS’s use-case conditions and a risk assessment. 1.4 The method used to create a breach, hole or defect in single-use film or...