USP <61> Microbiological Examination Of Nonsterile Products

Microbial enumeration testing is a key component in the manufacture of pharmaceuticals, cosmetics, and personal care products. The accepted end-to-end microbial enumeration testing process is detailed in USP <61> and is used to measure the levels of bacteria or fungi in products that may be consumed or used on the skin, especially around the eyes.

For these types of products, microbial limits for microorganisms are low, and microbial pathogens of high virulence must not be present in the product at all. USP <61> testing ensures consistent, repeatable testing and measurement of these levels, and also outlines methodology for sample collection, sample neutralization, and testing validation to ensure compliance and the utmost safety and accuracy. We will explore the details of USP Chapter <61> in further detail throughout this page.

BA Sciences maintains deep expertise in USP pharmacopoeia standards, including USP <61>. We feature the equipment and expertise to provide analytical method transfer for pharma, cosmetics, and personal care product companies, and we adhere to the most stringent standards in the industry in order to provide you with the highest level of service.

In addition to core testing processes, we ensure that our analytical method transfer, validation, and documentation processes are aligned with the highest industry standards, providing you with the confidence that your products are safe and effective while meeting GMP and other requirements.

Microbial Limits Under USP <61>

USP <61> outlines acceptable limits for different types of products. For cosmetic and personal care products, these limits are:

  • 100 CFU (colony forming units) or less per g or ml of product for baby products and eye-area products
  • 1000 CFU or less per g or ml of product for non-eye-area products

Further testing may also be required under USP <62> to determine the virulence of the pathogens present, as these types of products are not permitted to contain any high-virulence microorganisms.

USP <61> Testing Methods

There are several types of tests that may be carried out under USP <61>. BA Sciences focuses on one of the only legally accepted methods under the USP pharmacopoeia. This method is aligned with international methods including European and Japanese pharmacopoeia methods.

During testing, a product sample is added to a culture medium. In this culture, any microbes present will thrive and, within 3 – 5 days, form “colony units” that are visible to the naked eye. By counting these units, the amount of bacteria and fungi present can be determined.

USP <61> also covers a number of preparation and validation (suitability testing) steps to ensure the accuracy of the test. Any microorganism inhibitors in the sample must be neutralized, since these types of compounds are often found in the raw materials that are used in pharmaceutical and cosmetic manufacturing. If present, these inhibitors may yield inaccurate results, since they prevent microbes from growing and being counted.

In addition, the culture method must be validated to ensure that it is capable of supporting the growth of the target microorganisms. If the culture method does not present the right environment for the target microorganisms to grow, testing will be similarly inaccurate and will not detect the presence of microbes, potentially presenting a danger to end users.

At BA Sciences, we offer expertise in each of these areas and more and are ready to assist you in any testing and validation needs that you may have.

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