Drug – bio-affecting and body treating compositions – Inorganic active ingredient containing – Peroxide or compositions of or releasing gaseous oxygen or...
Reexamination Certificate
1999-07-19
2002-02-12
Pak, John (Department: 1616)
Drug, bio-affecting and body treating compositions
Inorganic active ingredient containing
Peroxide or compositions of or releasing gaseous oxygen or...
C424S601000, C424S602000, C424S603000, C424S604000, C424S605000, C424S606000, C424S126000, C424SDIG006, C422S012000, C422S028000, C514S553000, C514S557000, C514S558000, C514S559000, C514S560000, C514S574000, C514S576000, C514S709000, C514S970000, C504S151000
Reexamination Certificate
active
06346279
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to disinfectants, and in particular it relates to hydrogen peroxide solutions with improved disinfectant and antimicrobial properties.
BACKGROUND TO THE INVENTION
A wide range of disinfectants is known, as discussed for example in Disinfection, Sterilization, and Preservation, edited and partially written by Professor Seymour S. Block, Fourth Edition, published 1991 by Lea & Febiger, Pennsylvania. Certain peroxygen compounds, chlorine compounds, phenolics, quaternary ammonium compounds and surface active agents are known for their germicidal properties. The rate of disinfection is relatively slow in many cases, and some compounds emit volatile organic compounds or leave a persistent residue in the environment.
Hydrogen peroxide is finding favour in many applications because of the innocuous breakdown products of water and oxygen, and that it tends to have broad spectrum antimicrobial activity. Broad spectrum activity is important in situations where harmful organisms are present but their identity is not known. As hydrogen peroxide tends to be unstable and decomposes over time, steps must be taken to stabilize the hydrogen peroxide solutions if they are to be stored for any length of time. Various ways have been proposed to improve the stability of hydrogen peroxide compositions. For example, sodium stannate, sodium nitrate, and diethylene triamine penta(methylenephosphonic acid) have been reported as being useful as stabilizers, as disclosed in U.S. Pat. No. 5,523,012 to Winterton et al., which issued Jun. 4, 1996. Additionally, a major drawback of most disinfectants used heretofore has been the length of time needed to reduce the bacterial count after the disinfectant has been applied to a bacterially contaminated material. For example, it may take 30 minutes or more after application of the disinfectant to disinfect a treated surface. In many circumstances this rate of disinfection is far from satisfactory.
Combinations of hydrogen peroxide with various surfactants are known. For example, Winterton et al. discloses, in U.S. Pat. No. 5,523,012, a buffered disinfecting solution for contact lenses, which has from about 0.1% to about 1.0% of an ocularly compatible surfactant. Winterton disclosed that in one experiment, addition of about 0.4% anionic sulphosuccinate surfactant improved the killing time for
aspergillus fumigatus
to 6.9 minutes, compared to 9.4 minutes for a solution containing 0.1% nonionic surfactants. However, even 6.9 minutes is far too long for many applications.
The present invention is directed to improving the efficacy of hydrogen peroxide based solutions.
SUMMARY OF THE INVENTION
Accordingly the present invention provides an aqueous solution comprising i) hydrogen peroxide in a concentration of up to about 20 wt./wt. % of the solution, ii) at least one phosphorus-based acid in a concentration range of from 0.05 to 8.0 wt./wt. % of the solution, and iii) at least one anionic surfactant selected from the group consisting of C8 to C16-alkyl aryl sulphonic acids and alkali metal and ammonium salts thereof, sulphonated C12 to C22 carboxylic acids and alkali metal and ammonium salts thereof, C8 to C22-alkyl diphenyl oxide sulphonic acids and alkali metal and ammonium salts thereof, naphthalene sulphonic acids and alkali metal and ammonium salts thereof, C8 to C22 alkyl sulphonic acids and alkali metal and ammonium salts thereof, alkali metal C8 to C18 alkyl sulphates, and mixtures thereof, in a concentration range of from 0.02 to 5 wt./wt.% of the solution.
The pH of the solutions are preferably from about 1 to about 9, particularly from 1 to 7, and even more particularly from about 1 to about 3.
In one embodiment, the phosphorus-based acid is selected from the group consisting of phosphoric acid, phosphonates having from 1 to 5 phosphonic acid groups, and mixtures thereof.
In one embodiment, the phosphorus-based acid is selected from the group consisting of phosphoric acid, amino tri(methylene phosphonic acid), 1-hydroxyethylidene-1,1,-diphosphonic acid, diethylenetriaminepenta(methylene phosphonic acid), 2-hydroxyethylimino bis(methylene phosphonic acid), ethylene diamine tetra(methylene phosphonic acid) and mixtures thereof.
In a further embodiment, the solution contains up to about 3 wt./wt. % of at least one emulsifier.
In another embodiment, the emulsifier is selected from the group consisting of polyoxyethylene surfactants and hydrotropes, e.g. C8 to C16 alkylphenol alkoxylates. The hydrotrope may be selected from an alkylated sulphonated diphenyl oxide and an alkylated sulphonated diphenyl oxide sale. The emulsifier may be a C8 to C16 alkyl phenoxypolyethoxy ethanol.
In yet another embodiment, the emulsifier is octylphenyl ethoxylate.
In another embodiment, the solution has a hydrogen peroxide concentration of from 0.05 to 8.0 wt./wt. % of the solution.
In yet another embodiment, the solution has a hydrogen peroxide concentration of from 0.05 to 1.0 wt./wt. % of the solution.
In a further embodiment, the hydrogen peroxide concentration is from 3.0 to 8.0 wt./wt. % of the solution.
In yet another embodiment, the alkyl aryl sulphonate is dodecyl benzene sulphonate or an alkali metal salt thereof or an ammonium salt thereof.
In another embodiment, the solution contains phosphoric acid, a phosphonate having from 1 to 5 phosphonic acid groups, an anionic alkyl aryl sulphonic acid, an alkylphenol alkoxylate and an alkylated sulphonated diphenyl oxide salt.
In another embodiment, the solution contains a corrosion inhibitor.
In a further embodiment, the corrosion inhibitor is selected from the group consisting of a benzotriazole, a hydrobenzotriazole, a carboxybenzotriazole, sodium nitrite, sodium molybdate, sodium gluconate and sodium benzoate and combinations thereof.
In yet another embodiment, the corrosion inhibitor is present in a concentration of from 0.05 to 10.0 wt./wt. % of the solution.
In another embodiment, the solution contains from 0.1 to 10.0 wt./wt % of a C1 to C6 alcohol, e.g. methanol, ethanol and isopropanol.
In another embodiment, the solution contains a mono-or poly-carboxylic acid or mixtures thereof, e.g. acetic acid, glycolic acid, citric acid, succinic acid, or mixtures thereof, in a concentration of from about 0.05 to about 4.0 wt./wt. %.
In a further embodiment, the solution contains a non-ionic surfactant selected from the group consisting of alkylated alkoxylate surfactants, alkyl aryl alkoxylate surfactants and mixtures thereof.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In the past few years, efforts have been concentrated on developing chemicals that will be highly effective against microorganisms when highly diluted, will be low in toxicity to humans and other animals, and will not injure the environment. Of all the known disinfectants and antimicrobials, hydrogen peroxide appears to have exceptional potential, especially in terms of toxicity and injury to the environment because the decomposition products are benign. For example, at concentrations of 1-3 wt./wt. % aqueous solution, hydrogen peroxide is considered non-corrosive and non-irritating; at concentrations of 3-7 wt./wt. % aqueous solution, hydrogen peroxide is considered non-corrosive but an eye irritant; and at concentrations of above about 8 wt./wt. % aqueous solution, hydrogen peroxide is considered corrosive, more so at higher concentrations, and also a strong oxidizing agent.
The higher concentration levels of hydrogen peroxide solutions required to provide fast, effective action are not practical or economically viable, and may be subject to hazardous goods regulations and require special precautions for handling and use. Heretofore, one of the major drawbacks of hydrogen peroxide, in low concentrations, is that its antimicrobial action is too slow. A second major drawback is that it has not been considered possible to stabilize the peroxide sufficiently to make the solution commercially acceptable. For example, prior references indicate that a 0.1 wt./wt. % aqueous solution of hydrogen peroxide requires
Pak John
Ridout & Maybee LLP
Virox Technologies Inc.
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