Experience & Excellence

According to USP <71> Sterility Tests, membrane filtration is the sterility test method of choice for filterable pharmaceutical products. Membrane filtration refers to either an open membrane filtration (OMF) or closed membrane filtration system. Not all sterility test systems are the same. It is important pharmacists know the differences between the two systems to reduce the risk of false positive results, costly investigations, and batch loss.

USP <71> Sterility Tests is a general chapter enforceable by regulatory agencies and is applied to substances, preparations, and articles required to be sterile. This chapter demonstrates process control and is a general indicator of the microbiological quality of a product. It's important to note that the <71> "pharmacopeial procedures are not by themselves designed to ensure that a product or batch is sterile or has been sterilized. This is accomplished primarily by validation of the sterilization process or of the aseptic processing procedures." For ARL to list USP <71> as the test method, pharmacists must certify and submit the correct number of articles in accordance with Table 3 in the chapter.

A sterility test is performed under aseptic conditions. Precautions are taken to avoid contamination, so the testing environment does not impact any microorganisms that are to be revealed during the test. ARL Bio Pharma regularly monitors working test conditions by appropriate environmental sampling of the work area and carrying out suitable controls.  

ARL Sterility Test Process: 

• ARL performs growth promotion testing and assesses other quality parameters to confirm that each lot of ARL's media can support growth of the six microorganisms stated in USP <71> Sterility Tests.
• Prior to conducting a USP <71> sterility test, our laboratory performs method suitability for each specific product formulation to ensure that an appropriate method is chosen for testing.  
• During performance of a sterility test, ARL uses either a closed membrane filtration method (the preferred method, when possible) or a direct inoculation method for unfilterable sample types. To ensure that a sterility test is USP <71> compliant, ARL tests the correct sample volume according to Table 2 in the chapter. The test containers are then incubated at the appropriate temperatures for at least 14 days. 
• At the end of the incubation period, each test is examined for signs of microbial growth, which generally present as turbidity or cloudiness of the media.

At the conclusion of the test, if there is no evidence of growth, the drug product complies with the USP <71> test for sterility. A "Sterile" result indicates that no contaminating microorganism is found in the sample examined under the conditions of the test.

If the test reveals signs of contamination, the drug product is considered "Not Sterile" and an OOS investigation will be initiated.

For more information on Sterility Testing, visit the articles and webinar below: 

• Method Suitability and Its Importance to the Test Method
• Sterility Test Failure: Possible Causes and Investigation
• Basics of Sterility Testing
• Submitting Samples for Sterility Testing
• An Inside Look at USP <71> Webinar
• An inside Look at USP <71> FAQ