Preservatives

Preservatives are used in concentrations that prevent the growth of or kill microorganisms.
Many of the preservatives are toxic in large amounts or irritating when parenterally administered. Therefore, special care must be exercised when selecting preservative agents.
The maximum limit of certain preservatives used in parenteral products is as follows:Cationic surface-active compounds0.01%Chlorobutanol, cresol, and phenol0.5%Sulfite, bisulfite, or metabisulfite of potassium or sodium0.2%
In addition to the stabilizing effect of the additives, the air accompanying the injectable product is frequently replaced with an inert gas, such as nitrogen, to prevent oxidation and to enhance the stability of the product.