Benzalkonium chloride antimicrobial activity

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... 

In ophthalmic preparations, benzalkonium chloride is one of the most widely used preservatives, at a concentration of 0.01-0.02% w/v. Often it is used in combination with other preservatives or excipients, particularly 0.1% w/v disodium edetate, to enhance its antimicrobial activity against strains of Pseudomonas. 

The chemical modification of CS biopolymers via reductive amination, to yield alkylated CS derivatives, and further quaternisation result in very efficient antibacterial materials the degree of activity is correlated to the length of the alkyl chain and bacterial strain. The most active CS derivatives are more selective at killing bacteria than the quaternary ammonium disinfectants, cetylpyridinium chloride and benzalkonium chloride, and AMP. Vanillin can be used as a crosslinker of CS nsing this approach, functionalised antimicrobial polymers based on CS, vanillin. Tween 60 and so on may be easily prepared. Imino-CS biopolymer films, prepared by the acid condensation of the amino groups of CS with various aldehydes, can be used as functional biodynamic materials. 

Cationic surface active agents such as benzalkonium chloride and cetyltrimethylammonium bromide (Figure 1) have use as antibacterial agents, i.e., disinfectants and antiseptics, and have the advantage that the antimicrobial action is combined with a cleaning action associated with their detergent activity. 

Neither anionic nor non-ionic surfactants impair Bronopol s antimicrobial efficacy. For that reason the product is a most suitable preservative for detergent solutions, bath foams, shampoos and hair rinses. Bronopol is also compatible with quaternary ammonium compounds (Section 16.1) and cationic active ingredients such as benzalkonium chloride. 

The ciliotoxicity of some substances depends on the pH of the solution. For instance when benzalkonium chloride is used as preservative, the pH of the preparation should be >5 to reduce the ciliotoxicity. Preservative efficacy can also be dependent on pH of the formulation. For instance, antimicrobial activity of benzalkonium chloride occurs between pH 4 and 10, and methyl parahydroxybenzoate exhibits antimicrobial activity over the pH range of 4-8 [38, 39]. See also Sect. 23.8.2. 

Hypromellose (hydroxypropyhnethylcellulose, HPMC) 4,000 inPa-s 0.125-0.5 % or 1.25-5 mg/mL Hypromellose is a non-ionic cellulose polymer. Hypromellose is a component of the viscous vehicle hypromellose-benzalkonium solution (see Table 10.10). The concentration is % (10 mg/mL), but as it will be diluted 1 1 dining preparation of viscous eye drops, the final concentration will be 0.5 % (5 mg/mL). Hypromellose solutions are not always well tolerated because of stnface tension reduction of the tear film [30]. The antimicrobial activity of benzalkonium chloride is only slightly influenced by hypromellose [82]... 

The first observations to suggest that some quaternary ammonium compounds, such as benzalkonium chloride, stearalkonium chloride, and cetylpyridine chloride, have antimicrobial activity were made in as early as 1916, but their full potential was first realized in the 1930s [1, 2 J. Since then their uses have steadily increased and include many industrial purposes, water treatment, and antifungal treatment in horticulture, as well as inclusion in pharmaceutical and everyday consumer products. For example, benzalkonium chloride, the most commonly used, is found in products such as eye drops, artificial tears, decongestion nose drops, facial moistures, facial cleansers, acne treatments, sun protection creams and lotions, body lotions, moisturizers, pain relievers, and hand sanitizers [3 ]. Very often good reasons for their use are lacking and claims are limited to assertions that they are bug-killers . 

Microbial cellulose is found to be an optimal material for skin tissue repair due to its ability to provide a moist environment for wound healing and pain free dress changing. Unfortrmately, microbial cellulose itself has no antimicrobial activity to prevent wound infection. However the lack of antimicrobial activity of microbial cellulose is the main issue to be tackled. To improve the antimicrobial activity of microbial cellulose, researchers have introduced different materials such as benzalkonium chloride, chitosan and metallic nanoparticles into microbial cellulose. Among them metallic nanoparticles such as copper, silver [56] and ZnO [57] have been recently reported as excellent antimicrobial agents. Due to the electron-rich oxygen atoms in the microbial cellulose macromolecules and the large surface area of nanoporous microbial cellulose effective as nanoreactor, the in-situ metallization technique was successfully applied to the synthesis of Ag and microbial cellulose nanocomposite, which could in turn serve as antimicrobial skin tissue repair material. 

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