Effect of preservatives

Infection induced by contaminated 22 Effect of preservative concentration,... 

Effect of preservative concentration, temperature and size of inoculum... 

More subtle effects of preservatives on injectable formulations are possible. Formulation of insulin is an illustrative case study. Insulin is usually formulated as a multiple-dose vial, since individual dosage varies among patients. Preservation of zinc insulin with phenol causes physical instability of the suspension, whereas methyl-paraben does not. However, the presence of phenol is required for obtaining protamine insulin crystals [9]. 

Protein drugs have been formulated with excipients intended to stabilize the protein in the milieu of the pharmaceutical product. It has long been known that a variety of low molecular weight compounds have the effect of preserving the activity of proteins and enzymes in solution. These include simple salts, buffer salts and polyhydroxylated compounds such as glycerol, mannitol, sucrose and polyethylene glycols. Certain biocompatible polymers have also been applied for this purpose such as polysaccharides and synthetic polymers such as polyvinyl pyrrolidone and even nonionic surfactants. 

In this chapter, it is emphasized that antimicrobial preservatives should not be used as a substitute to GMPs or solely to reduce the viable microbial population of a nonsterile product. It is recommended that antimicrobial effectiveness of preservatives must be demonstrated for dosage forms such as multiple-dose topical and... 

Important specifications for the manufacture of all solutions include assay and microbial limits. Additional important specifications for suspensions include particle size of the suspended drug, viscosity, pH, and in some cases, dissolution. Viscosity can be important, from a processing aspect, to minimize segregation. In addition, viscosity has also been shown to be associated with bioequivalency. pH may also have some meaning regarding effectiveness of preservative systems and may even have an effect on the amount of drug in solution. With regard to dissolution, there are at least three products that have dissolution specifications. These products include pheny-toin suspension, carbamazepine suspension, and sulfamethoxazole and trimethoprim suspension. Particle size is also important, and at this point it would seem that any... 

Green, K. 1993. The effects of preservatives on corneal permeability of drugs. In Biopharmaceutics of Ocular Drug Delivery, ed. Edman, P., 43. Boca Raton, FL CRC Press. 

Sasaki, H. 1994. Effect of preservatives on systemic delivery of insulin by ocular instillation in rabbits. J Pharm Pharmacol 46 871. 

In the past, it has been well documented that the relative permeability of wood has a significant influence on the effectiveness of preservative treatments. Without adequate penetration, even the best preservatives will not provide sufficient protection and the wood will fail prematurely. Consequently, any developments in methods which increase the treatability of wood which are difficult to treat could have a significant impact on the wood preserving industry. 

Effectiveness of Preservative Manufacturing controls and shelf life must ensure that the specified preservative level is present and effective as part of the stability program [6], Depending on the type of product, the selection of the preservative system is based on different considerations, such as site of use, interactions,... 

Albietz J, Bruce A. The conjunctival epithelium in dry eye subtypes effect of preserved and non-preserved topical treatments. Curr Eye Res 2001 22 8-18. 

Table V. Effects of Preservatives on the Mechanical Properties of Wood...

Another detrimental effect of preservative-wood interaction is the formation and buildup of colloidal material in the treating solutions as it is recycled. This particulate matter arises from an interaction between the preservative chemicals and wood components and often results in a significant decrease in the penetrability of the treating solution (54). 

The contamination of pharmaceutical suspensions for oral use is a cause of concern. The behaviour of organisms in such suspensions therefore needs to be examined before interpretation of experimental results can be undertaken. Under some conditions, bacteria may be strongly adsorbed and therefore more resistant to the effects of preservatives in other cases, the bacteria may be free in suspension. 

Food acidulants find their application, for the greater part, in beverages and in fruit and vegetable processing. Apart from pH lowering, acidulants provide buffer capacity, impair sourness and tartness, enhance the effect of preservatives, and for some acidulants such as citric acid, prevent discoloration caused by trace metals (Seifert, 1992). 

Lebow ST and Morrell JJ (1995) Interactions of ammoniacal copper zinc arsenate (ACZA) with Douglas fir. Wood and Fiber Science, 27(2) 105-18 Lebow ST and Tippie M (2001) Guide for minimizing the effect of preservative-treated wood on sensitive environments. USDA, Forest Service, Forest Products Laboratory, General Technical Report FPL-GTR-122... 

Manufacturing controls necessary to maintain the antimi-crobiological effectiveness of preservatives should be evaluated. For example, for those products that separate on standing, there should be data available that show the continued effectiveness of the preservative throughout the product s shelf life. 

Solution We will assume that soda is an equilibrium mixture of water and carbon dioxide and will ignore the effect of preservatives, sweeteners, and color agents on the thermodynamic properties. A good estimate for the pressure in the can is about 2 bar. The equilibrium conditions for water and carbon dioxide are ... 

Podgorska E (1992) Effect of Preservatives on Patulin Production by Penicillium expansum. Acta Microbiologica Polon 41 97... 

Tehrani FA, Ahmadiani A, Niknejad H. The effects of preservation procedures on antibacterial property of amniotic membrane. Cryobiology 2013 67 293-8. 

Lochhead, A. G., and Farrell, L. 1936. Effect of preservatives on fermentation and viability of sugar-tolerant yeasts. Food Research 1, 517-524. 

Mallants R, Jorissen M, Augustijns P (2007) Effect of preservatives on ciliary beat frequency in human nasal epithelial cell culture single versus multiple exposure. Int J Pham 338 64—69... 

---