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Antimicrobial preservatives are added to pharmaceutical and
cosmetic preparations that have inadequate anti-microbial activity to
prevent proliferation or minimise contamination by micro-organisms.
A number of factors may affect the efficacy of the antimicrobial
preservative including; the active constituent of the pharmaceutical
preparation, the formulation in which it is incorporated or the container
and closure used for packaging and storage.
During development of such preparations it is a requirement to
demonstrate that the antimicrobial activity of the preparation, together
with the addition of a suitable preservative (if necessary) will provide
adequate protection against the effects of microbial contamination or
proliferation incurred during storage or use.
Preservative efficacy testing is used to validate that antimicrobial
activity has not been impaired by storage and is based on standard
microbiology cell culturing techniques. A sample of the product in its
final container (when possible) is inoculated with a microbial suspension of
a population of prescribed organisms and stored at a temperature as
typically described in USP Chapter 51. Samples are tested at different
intervals to determine the survival of the organisms. The preservative
properties of the preparation are deemed adequate if there is no increase or
a significant fall (as appropriate in the number of micro-organisms in the
inoculated preparation) after the time and temperature prescribed. The
criteria of acceptance in terms of decrease in the number of micro-organisms
with time, varies for different types of preparations according to the
degree of protection intended.
Honeyman perform preservative efficacy testing in accordance with BP, EP
and USP standards on a number of products including injections packaged in
multiple-dose containers, multiple-dose topical and oral forms and for other
dosage forms which contain antimicrobial preservatives including opthalmic,
otic, nasal irrigation and dialysis fluids. |
