Phenylmercuric nitrate

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... 

Substances that have been used as preservatives for disperse systems include chlorocresol, chlorobutanol, benzoates, phenylmercuric nitrate, parabens, and others [76,77]. The use of cationic antimicrobial agents such as quaternary ammonium compounds (e.g., benzalkonium chloride) is contraindicated in many cases because they may be inactivated by other formulation components and/or they may alter the charge of the dispersed phase. Clay suspensions and gels should be adequately preserved with nonionic antimicrobial preservatives. The use of preservatives is generally limited to products that are not intended for parenteral use. Intravenous injectable... 

Reproducibility evaluation of toxicity test of phenylmercuric nitrate 187... 

Another group possessing activity against -SH groups in enzymes are the organic mercurials such as mercurochrome, nitromersol (23), phenylmercuric nitrate and... 

It seems to be certain that the oxynitration reaction in the presence of mercury salts proceeds through the formation of phenylmercuric nitrate. The isolation of phenylmercuric nitrate from a reaction mixture in dilute nitric acid by several authors (Carmack and his co-workers [135], Titov and Laptev [71], and also Bro-ders [124]) favours this view. If an intermediate nitroso compound is formed in the reaction its formation should be ascribed to the reaction between phenylmercuric nitrate and nitrous acid. This view, based on earlier experiments of Baeyer [136], Bamberger [137], Smith and Taylor [137a], has since been confirmed by Westheimer, Segel and Schramm [138], who considered the nitroso compound formed from an organo-mercuric compound to be the principal intermediate product in the Wolffenstein and Boters reaction. 

Prepare a 500-ml filter flask to receive the potato extract by pouring 250 ml of F O into it and marking the position of the top of the fluid in the filtration reservoir with a felt-tipped pen. Pour out the F120. Suspend about 100 mg of phenylmercuric nitrate in a few milliliters of H20 and pour it into the filter flask. Phenylmercuric nitrate is added to inhibit other enzymes and to prevent bacterial growth during the incubation of potato phosphorylase with starch. 

Of the mercurial preservatives, thimerosal is less subject to degradation into toxic mercury than either phenylmer-curic acetate or phenylmercuric nitrate. Thimerosal is most effective in weakly acidic solutions. Some patients, however, develop a contact sensitivity and must discontinue use after several weeks or months of exposure. Because thimerosal affects internal cell respiration and must be present at high continuous concentrations to have biologic effects, its dilution by the tear film prevents short-term epithelial toxicity on single appUcation. It has no known effects on tear film stability. A concentration of 1% thimerosal is required to equal the effects on corneal oxygen consmnption of 0.025% BAG. 

Associated with pilocarpine solutions containing phenylmercuric nitrate as preservative. 

Phenylmercuric nitrate IM, ophthalmic, topical Halides, aluminium, amino acids, some plastics, rubber... 

Gantrisin ophthalmic solution Sulflsoxazole Phenylmercuric nitrate... 

The degree of ionization of acidic and basic antimicrobial agents depends on pH. Some compounds are active only in the unionized state (e.g., phenolics) whereas others are preferentially active as either the anion or cation. It therefore follows that the activity of a particular concentration of an agent will be enhanced at a pH that favors the formation of the active species. Thus, cationic antibacterials such as acridines and quaternary ammonium compounds are more active under alkaline conditions. Conversely, phenols and benzoic acid are more active in an acid medium. Chlorbutol is less active above pH 5 and unstable above pH 6. Phenylmercuric nitrate is only active at above pH 6 whereas thiomersal is more active under acid conditions. The sporicidal activity of glutaraldehyde is considerably enhanced under alkaline conditions whereas hypochlorites are virtually ineffective at above pH 8. 

Parkin JE, Duffy MB, Loo CN. The chemical degradation of phenylmercuric nitrate by disodium edetate during heat sterilization at pH values commonly encountered in ophthalmic products. J Chn Pharm Ther 1992 17(5) 307-14. 

Aryl mercurials that have been used medicinally include phenylmercuric acetate, phenylmercuric nitrate, nitromersol, thiomersal, merbromin (mercurochrome), and mercurobutol. These compounds are variously used as preservatives in drugs, including vaccines, for skin disinfestation, the treatment of infections of the skin and mucosa, and in contraceptive jellies and hemorrhoidal remedies they have also been used in some cosmetics. The aryl mercurials are better absorbed across the mucous membranes than most inorganic mercury salts. 

The use of mercurials in the eye can lead to a bluish-gray deposit of mercuric oxide on the eyelids, conjuncti-vae, and Descemet s layer. Phenylmercuric nitrate used in a 0.004% concentration can cause mercuria lentis. Mercurial compounds have been found in the aqueous humor, having penetrated the eye from hydrophilic-gel contact lenses preserved with thiomersal. Although it remains to be established whether deposition of mercury in the eye is clinically important, the concentrations found are similar to those reported in cases of systemic poisoning by organic mercurials (64). 

The use of mercury in fhe treafment of diseases such as syphihs, psoriasis, and congestive heart failure began more fhan fwo cenfuries ago. Although mercury s medicinal use has tapered off in recent years, mercury compounds such as thimerosal and phenylmercuric nitrate still have a limited use in human and veterinary medicines to prevent bacterial growth in injection solutions (e.g. vaccines), antiseptics, and skin ointments. The United States Food and Drug Administration [1] estimates that approximately 200 human and veterinary drug products marketed in the U.S. contain mercury as an active or inactive ingredient. 

Spores benzyl alcohol is inactive against spores, but activity may be enhanced by heating. Benzyl alcohol 1 % v/v, at pH 5-6, has been claimed to be as effective as phenylmercuric nitrate 0.002% w/v against Bacillus stearothermophilus at 100°C for 30 min. 

Incompatible with soaps, anionic surfactants, high concentrations of nonionic surfactants, bentonite, iodine, phenylmercuric nitrate, alkali hydroxides, and acid dyes. Aqueous solutions react with metals. 

Phenylmercuric acetate is used as an alternative antimicrobial preservative to phenylmercuric borate or phenylmercuric nitrate in cosmetics (in concentrations not exceeeding 0.0065% of mercury calculated as the metal) and pharmaceuticals. It may be used in preference to phenylmercuric nitrate owing to its greater solubility. 

Antimicrobial activity phenylmercuric acetate is a broad-spectrum antimicrobial preservative with slow bactericidal and fungicidal activity similar to phenylmercuric nitrate see Phenylmercuric Nitrate. 

Phenylmercuric acetate is mainly used as an antimicrobial preservative in topical pharmaceutical formulations. A number of adverse reactions to mercury- containing preservatives have been reported see Phenylmercuric Nitrate. 

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