The essentials of United States Pharmacopeia Chapter <51> antimicrobial effectiveness testing and its application in pharmaceutical compounding.

Antimicrobial preservatives are excipients added to multi-dose containers of both sterile and non-sterile drug products. Antimicrobial preservatives are used primarily to inhibit growth of microbial contamination occurring during the period of use. Demonstration of antimicrobial preservative effectiveness is required for these functional excipients. This article reviews key factors for consideration in the selection of preservatives, principles of the preservative-effectiveness test, and the significance of requirements for preservative-effectiveness testing in the compounding practice.