Sterility testing microbial limit test

Microbiological aspects will need to be discussed, but the amount of information will depend on the type of product. For nonsterile products there will need to be a description of the microbiological attributes of the product and, if appropriate, a rationale for not performing microbial limit tests. For preserved products the selection of the antimicrobial preservatives will need to be discussed and the effectiveness of the selected system demonstrated. For sterile products there will need to be appropriate process validation data and information on the integrity of the container-closure system. 

These tests would include compendial tests for Microbial Limits, Sterility, Bacterial Endotoxins, and Antimicrobial Effectiveness. 

The tests for microbial limits and recommendations for microbial quality criteria of raw materials, excipients, drug substances, and pharmaceutical products have been established in pharmacopoeial compendia for over 30 years. These tests are listed in the USP 24 Chapter (61) Microbial Limits Tests and in the Ph. Eur. 3rd ed.. Biological Tests 2.6.12 and 2.6.13, Microbial Contamination of Products Not Required to Comply with the Test for Sterility (total viable count, tests for specified microorganisms) and the JP XIII 30 Microbial Limit Test. 

The USP 24 General Notices state that alternative methods may be used to determine that products comply with the pharmacopoeial standards for the advantages in accuracy, sensitivity, precision, selectivity, adaptability to automation or computerized data reduction, or any other special circumstances. Such alternative or automated methods shall be validated However, when disputed, the compendial method is conclusive as it is the official or referee test. In addition, USP Chapter (61) Microbial Limit Tests states that automated methods may be substituted provided they are validated and give equivalent or better results, whereas USP Chapter (71) Sterility Tests states that alternative procedures may be employed to demonstrate that an article is sterile, provided the results obtained are at least of equivalent reliability. 

USP 24 Testing Chapters (51) Antimicrobial Effectiveness Testing, (61) Microbial Limit Tests and (71) Sterility Tests, United States Pharmacopeial Convention, Inc., Rockville, MD, 2000. USP 24 Informational Chapters (1116) Microbiological Evaluation of Clean Rooms and other Controlled Environments, (1111) Microbiological Attributes of Pharmaceutical Articles, (1151) Pharmaceutical Dosage Forms, (1225) Validation of Compendial Methods, and (1231) Water for Pharmaceutical Purposes, United States Pharmacopeial Convention, Inc., Rockville, MD, 2000. 

To address protection, use of tests (see Attachment A) for light transmission, moisture permeation, microbial limits, and sterility are generally considered sufficient. Testing for properties other than those described above (e.g., gas transmission, solvent leakage container integrity) may also be necessary. 

If microbial growth is detected in a sterility test, this may reflect a falsepositive reading because of the problem of accidental contamination of the culture media while performing the sterility test. The problem of accidental contamination is a serious yet unavoidable limitation of the sterility test. 

ICH-EWG-Q developed a list of 12 general chapters (tests and assays) that were deemed critical to new product registration and urged the PDG to concentrate on prompt harmonization (see Appendix III). Qne of these, Antimicrobial Preservatives Effectiveness, was dropped in 1999 when non-harmonizability was clear because of differences in the essence of utilization of the same microbiological procedure. Of the 11 remaining chapters, all but two (Microbial Limits of Non-Sterile Articles and Dose Uniformity) were harmonized with regard to scientific content by the end of 1999 only the necessary publication sequences were unfinished. 

Requirements are not specified in the pharmacopeias for sample sizes appropriate to testing batches of non-sterile products for compliance with microbial limits. The test is destructive to the product, and it is extremely unlikely that statistically valid sampling plans are in use anywhere samples composed of 10 1-g amounts taken from 10 separate 15-g tubes of cream, or of three 3.3-ml amounts taken from three separate 500-ml bottles of syrup, may be typical. 

The Microbial Limit Test is, like the Test for Sterility, only confirmatory. It is not generally mandatory to test each batch of every non-sterile product for compliance with microbial limits. The exception is in the United States where it is mandatory to test every batch of non-sterile product. At the time of writing (early 2001), the FDA has proposed a relaxation of this rule for future registrations. However, in the case of tablets there is no requirement to register microbial limits, and therefore testing is not mandatory. The logic behind this is that the water content of tablets is too low to allow proliferation of microbiological contaminants. 

These tests include compendial tests for microbial limits, sterility, bacterial endotoxins, and antimicrobial effectiveness. 

Products not Required to Comply with the Test for Sterility (Total Viable Count, Tests for Specified Micro-Organisms) and JP Xin 30, Microbial Limit Test. 

The inclusion of a routine Microbial Limit Test in a marketed product stability protocol will depend on the pharmaceutical dosage form. Typically, the test would be used for only non-sterile products, particularly oral liquids, nasal sprays and topical liquids, lotions and creams that have a sufficient water activity to support the growth of microorganisms. In contrast, tablets, powder and liquid-filled capsules, topical ointments, vaginal and rectal suppositories,... 

Testing Chapters Antimicrobial Effectiveness Testing, Ch. 51 Microbial Limit Tests, Ch. 61 Sterility Tests, Ch. 71. In U.S.P. 24. 

USP-type preservative effectiveness test USP microbial limits test Shelf life-testing requirements Shelf life sterility... 

Due to the rapid advancement of new pharmaceutical delivery systems, this chapter covers only a limited number of techniques. Several of the techniques listed below may be necessary only at time zero or at release rather than being monitored at each stability time point. In addition, this chapter does not cover microbiological tests such as microbial limit, pyrogen, and sterility testing. 

In addition, other tests specific to the drug substance and formulation may apply, such as sterility, microbial limits, bacterial endotoxin, and pH. These types of tests would also be called for in order to comply with local pharmacopoeial requirements. Tests for subvisible particles beyond what is required in the pharmacopoeia may also be necessary due to immunogenicity concerns [29]. 

Tests for microbial limits may also have to be considered depending on the nature of the API, its method of manufacture, and its intended use. Sterility testing may be appropriate for APIs that will be used in parenteral or oral solution products that are sterile. Endotoxin testing may be needed for APIs intended for injectable products. Testing for the total count of aerobic microorganisms, yeasts, and molds and the absence of specific objectionable bacteria, such as Staphylococ-cus aureus, Escherichia coli. Salmonella, and Pseudomonas aeruginosa, may also be required. The tests described in the various compendia are generally used. 

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