The Preservative Effectiveness Test
To perform the preservative effectiveness test (also known as the preservative challenge test) on samples of pharmaceutical or cosmetics formulations, Merck provides a comprehensive range of granulated dehydrated culture media.
Preservatives are added to pharmaceuticals and cosmetics to inhibit the growth of or kill microorganisms that may be introduced during multiple withdrawals of the product from its container. The preservative effectiveness test is described in USP <51> (Antimicrobial Effectiveness Test, AET) and EP 5.1.3 (Efficacy of Antimicrobial Preservation) as a means to measure the biological activity of a product’s preservative system. A controlled inoculum of the challenge organism(s), such as Staphylococcus aureus or Escherichia coli, is placed in suspension with the sample to be tested. The number of surviving microorganisms is subsequently determined over time.
Merck provides high quality media for performing the preservative effectiveness test. These consistent culture media are available in a variety of formulations as dehydrated culture media in the form of granules.
Merck’s uniquely granulated culture media are not only convenient but also safe. In addition, they meet the highest industry performance standards as laid out in ISO 11133. The granules cause significantly less dust than powdered media, leading to less inhalation of hazardous media components that may cause allergic reactions, and minimizing contamination of the work environment. All Merck media are quality controlled according to stringent standards to guarantee the consistent high quality of our products.