Antimicrobial Preservative Efficacy Testing | Bioscience Labs

Antimicrobial Preservative Efficacy Testing

Antimicrobial Preservative Efficacy Testing

Antimicrobial Effectiveness Tests, or Preservative Effectiveness Tests, are performed to determine the efficacy of the antimicrobial preservatives added to many pharmaceutical and cosmetic products to prevent contamination over a period of time. Products are challenged with microorganisms either determined by the specific guidance criteria or chosen for relevance to the product, and the product is sampled at different time intervals over the course of not less than 28 days. There are several different guidance documents that address the Preservative Efficacy Testing and criteria such as: U.S. Pharmacopeia <51>, European Pharmacopeia 5.1.3, International Organization for Standardization (ISO) 11930 and Personal Care Products Council (PCPC) M-3 and M-4. Although these guidance documents are very similar, different criteria are called out in each one. In addition, many manufacturers choose to design custom assays designed to address specific contamination risks for their product. Typically, a neutralization validation is also performed as part of the assay, however manufacturers will occasionally perform the assay without performing the neutralization during the product formulation phase to determine the most effective concentration to add to the formula. BioScience Laboratories recommends always performing the neutralization validation step whenever you are conducting a preservative efficacy test.

BioScience Laboratories can help with all your Preservative Effectiveness Testing needs. Contact us today and we can help you identify the best PET assay for your products! 


In-Vitro Testing Laboratory

Scientists in our In-Vitro testing labs are well trained on ASTM, AATCC, AOAC, CLSI and EN standard methods. The efficacy testing services of this laboratory include MIC/MBC, biofilm prevention and removal, time-kill kinetics, clean room disinfectant validation, zone of inhibition and custom efficacy studies for disinfectants, antimicrobials and other products requiring EPA registrations and FDA 510(k) submissions. Studies in our…

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ASTM - E640

Standard Test Method for Preservatives in Water-Containing Cosmetics

This test method covers the determination of the suitability of preservatives for use in cosmetic formulations. It sets minimal requirements for preservative performance in model formulations.

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Personal Care Products Council (PCPC)

Preservation Testing of Water-Miscible Products

Challenge testing a formula with known microorganisms to verify that if the products become contaminated, the preservative system is sufficient to inhibit the growth of the microorganisms and spoilage. The CTFA M-3 (much like the USP 51) is a challenge method that is designed for water-based…

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USP 51


The U.S. Pharmacopeia describes in General Chapter 51, the assay they recommend for testing preservative efficacy. The USP divides products into four categories:

Category 1 - Injectable, emulsion, otic, sterile nasal and opthalmic products made in aqueous bases

Category 2 – Topically used products made…

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ISO 11930

The International Organization for Harmonization is designed for cosmetic formulations. Unlike the USP 51 or EP 5.1.3, ISO does not divide products into different categories. Test products are challenged with five microorganisms at three time points are sampled over the course of 28 days. 

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EP 5.1.3

The European Pharmacopeia describes in General Text 5.1.3, the assay they recommend for testing preservative efficacy. The EP divides products into three tables:

5.1.3-1 - Parenteral and ophthalmic preparations

5.1.3-2 - Topical preparations

5.1.3-3 - Oral preparations

Each category of products is challenged with four microorganisms independently and samples are…

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