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ILS - International Laboratory Services -Pharmaceutical Microbiology Preservative Efficacy Testing - Wide Range of Preparations


Preservative Efficacy Testing (PET Testing)

ILS can test a range of pharmaceutical preparations for preservative efficacy, including parenteral, ophthalmic, oral liquid, ear preparations and topical preparations.

ILS perform both methods of assessment is the EP/BP and USP preservative efficacy test (PET).

If a pharmaceutical preparation does not itself have adequate antimicrobial activity, antimicrobial preservatives may be added, particularly to aqueous preparations, to prevent proliferation or to limit microbial contamination which, during normal conditions of storage and use, particularly for multidose containers, could occur in a product and present a hazard to the patient from infection and spoilage of the preparation.

Antimicrobial preservatives must not be used as a substitute for good manufacturing practice.

The efficacy of an antimicrobial preservative may be enhanced or diminished by the active constituent of the preparation or by the formulation in which it is incorporated or by the container and closure used. The antimicrobial activity of the preparation in its final container is investigated over the period of validity to ensure that such activity has not been impaired by storage.

During development of a pharmaceutical preparation, it shall be demonstrated that the antimicrobial activity of the preparation as such, if necessary, with the addition of a suitable preservative or preservatives provides adequate protection from adverse effects that may arise from microbial contamination or proliferation during storage and use of the preparation.

The test consists of challenging the preparation, wherever possible in its final container, with a prescribed inoculum of suitable micro-organisms storing the inoculated preparation at a prescribed temperature, withdrawing samples from the container at specified intervals of time and counting the organisms in the sample removed.

The preservative properties of the preparation are adequate if, in the conditions of the test, there is a significant fall, or no increase, as appropriate, in the number of micro-organisms in the inoculated preparations after the time and temperatures prescribed. The criteria of acceptance in terms of decrease in the number of micro-organisms with time, vary for different types of preparations according to the degree of protection intended.

For more information or to obtain a free quotation for your testing requirements, please contact us

For pharmaceutical industry updates and information, including changes to regulations and methods, please go to the Industry Information page.