Preservatives Pseudomonas aeruginosa

Examples of preservatives are phenylmercuric nitrate or acetate (0.002% w/v), chlorhexidine acetate (0.01 % w/v), thiomersal (0.01 % w/v) and benzalkorrium chloride (0.01 % w/v). Chlorocresol is too toxic to the comeal epithehum, but 8-hydroxyquinoline and thiomersal may be used in specific instances. The principal considerahon in relation to antimicrobial properties is the activity of the bactericide against Pseudomonas aeruginosa, a major source of serious nosocomial eye infections. Although benzal-konium chloride is probably the most active of the recommended preservatives, it cannot always be used because of its incompatibility with many compounds commonly used to treat eye diseases, nor should it be used to preserve eye-drops containing anaesthetics. Since benzalkonium chloride reacts with natural mbber, silicone or butyl rabber teats should be substituted. Since silicone mbber is permeable to water vapour, products should not be stored for more than 3 months after manufacture. As with all mbber components, the mbber teat should be pre-equilibrated with the preservative prior to... 

The types of microorganisms found in various products are Pseudomonas species, including Pseudomonas aeruginosa, Salmonella, species, Staphylococcus aureus, and Escherichia coli. The USP and other pharmacopoeias recommend certain classes of products to be tested for specified microbial contaminants, e.g., natural plant, animal, and some mineral products for the absence of Salmonella species, suspensions for the absence of E. coli, and topically administered products for the absence of P. aeruginosa and S. aureus. Emulsions are especially susceptible to contamination by fungi and yeasts. Consumer use may also result in the introduction of microorganisms. For aqueous-based products, it is therefore mandatory to include a preservative in the formulation in order to provide further assurance that the product retains its pharmaceutically acceptable characteristics until it is used by the patient. 

Organic mercury compounds Silver compounds Preservation or antisepsis Application to wounds Important pharmaceutical preservations Effective against Pseudomonas aeruginosa... 

Two categories of microorganisms are cause for concern in preservation of topical semisolid products. They are those liable to cause pathogenic symptoms and include staphylococci and hemolytic streptococci. Pseudomonas aeruginosa and cepacia, and Escherichia coli, and microorganisms liable to cause spoilage, which include water and airborne molds and yeasts. The following section describes the properties of some commonly used preservatives. 

Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that binds certain metals, especially iron and copper, which are essential to the nutrition of certain microorganisms. In this manner, it is a strong booster or enhancer of the activity of preservatives especially the parabens. Alone, it has the ability to increase the permeability of the bacterial cell wall and can kill Pseudomonas aeruginosa and E. coli by this activity effective concentration is 0.05-0.10%. 

Bronopol owes its usefulness as a preservative largely to its activity against Pseudomonas aeruginosa, and its affinity for polar solvents, which prevents the loss of preservative into the oil phase of emulsions that is seen with some other preservatives. Other advantages include a low incidence of microbial resistance low concentration exponent and good compatibility with most surfactants, other excipients, and preservatives, with which it can therefore be used in combination. 

Palanichamy S, Ramakrishnan PN, Balasubramanian S, et al. Preservation of sodium chloride eye lotion BPC against contamination with Pseudomonas aeruginosa. Indian Drugs 1982 19 153-155. 

Antimicrobial activity similar to imidurea. " Diazolidinyl urea is the most active of the imidazolidinyl family of preservatives. Used in concentrations of 0.1-0.5% w/w, at pH 3-9, it has predominantly antibacterial properties. Typical MICs are Aspergillus niger 4000 pg/mL Candida albicans 8000 pg/mL Escherichia coli 1000 pg/mL Pseudomonas aeruginosa lOOOpg/mL Staphylococcus aureus 250 pg/mL. 

Kohn SR, Gershenfeld L, Barr M. Effectiveness of antibacterial agents presently employed in ophthalmic preparations as preservatives against Pseudomonas aeruginosa. J Pharm Set 1963 52 967-974. 

Drugs able to affect outer-membrane integrity have also been exploited as potentiators of antimicrobial agents (biocides, i.e. disinfectants, antiseptics and preservatives, and antibiotics) thereby helping these to penetrate the outer membrane of Gramnegative organisms and especially Pseudomonas aeruginosa. 

These findings prompted the development and evaluation of the currently available form of inhaled tobramycin, which is sterile and free of preservatives. The benefit of maintenance therapy with this inhaled tobramycin is supported by the results from two 24-week, multicenter, randomized, double blind, placebo-controlled clinical trials [6]. In these studies, patients with cystic fibrosis were at least six years of age, with an FEVj between 25% and 75% predicted. All subjects had evidence of colonization with Pseudomonas aeruginosa. Exclusion criteria included an elevated serum creatinine or colonization with Burkholderia cepacia, which is typically resistant to tobramycin. Subjects in the active treatment arm received inhaled tobramycin 300 mg twice daily through... 

Tobramycin solution for inhalation has approval from the Food and Drug Administration (FDA) for maintenance therapy in patients with cystic fibrosis and who are colonized with Pseudomonas aeruginosa. The commercially available formulation is a 300 mg per 5mL. It is a sterile, preservative-free product that is pH adjusted to 6.0. According to the labeling, this product should be used with a specific nebulizer, the Pari C Plus. 

The minimum inhibition concentrations range between 10 mg/litre against Staphylococcus aureus and 1000 mg/litre against Escherichia coli and Pseudomonas aeruginosa. The efficacy against fungi is not very distinctive. Mainly because of its good skin compatibility Bromochlorophen is used as a preservative in cosmetics and an additive in deodorants. The EC positive list of preservatives for cosmetics mentions a maximum authorized concentration of 0-1%. 

The a-glycerolether is prepared by condensing equimolar amounts of 4-chlorophenol (7.5.1.) and 2,3-epoxy-l-propanol (Glycidol) in the presence of a tertiary amine or a QAC as catalyst. Minimum inhibiton concentrations (source Kabara, 1984, e.g. 1250 mg/1 for Staphylococcus aureus, 2500 mg/1 for Pseudomonas aeruginosa and Aspergillus niger, 1250 mg for Candida albicans) present Chlorphenesin as a microbicide of moderate efficacy. Optimum pH range 4-6. Chlorphenesin is used as a preservative in cosmetic and pharmaceutical products. In the EEC Cosmetic Directive it is listed with a maximum permitted concentration of 0.3%. 

---