Drug – bio-affecting and body treating compositions – Inorganic active ingredient containing – Elemental chlorine or elemental chlorine releasing inorganic...
Reexamination Certificate
1997-05-23
2001-03-27
Pak, John (Department: 1616)
Drug, bio-affecting and body treating compositions
Inorganic active ingredient containing
Elemental chlorine or elemental chlorine releasing inorganic...
C424S661000, C424S663000, C422S029000, C422S037000, C205S500000, C510S370000, C510S380000, C252S187240, C252S187250, C252S187260
Reexamination Certificate
active
06207201
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composition containing an alkali metal or alkaline earth metal hypochlorite as the active ingredient for the disinfection and sterilization of hard surfaces and plastic, metal and glass instruments for surgery and dentistry. The present invention also relates to a method of disinfecting or sterilizing hard surfaces or surgical and dental instruments with solutions of alkali metal or alkaline earth metal hypochlorites.
BACKGROUND OF INVENTION
Since the 18th century, chlorine-based disinfectants have been employed in medical applications for their rapid, potent and broad-spectrum bactericidal activity. For example, Dakin developed a chlorine solution which subsequently proved useful for lavaging foul wounds. See H. D. Dakin,
Brit. Med. J
., ii:809 (December 1915). Chlorine Has also been widely used as a germicide in water and sewage Treatment.
Among the useful chlorine-based disinfectants are alkali metal and alkaline earth metal hypochlorites. Sodium, potassium, lithium and calcium hypochlorites are known for their disinfecting and bleaching properties. See e.g., U.S. Pat. No. 3,717,580 to Echols et al.
Despite the long history of efficacious use of chlorine-based disinfectants, few chlorine compounds are used today as sterilants in medical and dental practice. The many problems associated with chlorine-based disinfectants limit their usefulness for disinfecting or sterilizing instruments or hard surfaces. For example, the instability of the active ingredient causes the effectiveness of some hypochlorite disinfectant solutions to deteriorate significantly within a few hours of preparation.
An even more significant problem associated with use of chlorine-based disinfectants, however, is the highly corrosive nature of these solutions due to high oxidation potential. For example, concentrations of hypochlorous acid sufficient to sterilize standard bacteriological challenges also quickly attack metals, even stainless steel, causing discoloration and pitting. Metal instruments soaked in chlorine solutions tend to be irreversibly damaged; sharp edges are destroyed and metal surfaces are pitted and darkened.
As a result, corrosion inhibitors have been recommended for use with hypochlorites. See, e.g., G. H. Botham et al., “Corrosion by Commercial Sodium Hypochlorite and its Inhibition,”
J. Dairy Res
, vol. 16, 37 (1949). The use of corrosion inhibitors, however, has been plagued with problems, such as the reactivity of many inhibitors with chlorine and the resulting deactivation of the disinfectant solution.
Accordingly, there is a great need in the medical and dental arts for a disinfectant which will allow the rapid and effective sterilization of medical and dental instruments and hard surfaces at room temperature without corrosive effects and which exhibits sufficient chemical stability.
SUMMARY OF INVENTION
A first embodiment of the present invention is directed to an aqueous disinfectant solution comprising an alkali metal or alkaline earth metal hypochlorite, an amount of base sufficient to raise the pH of the solution to at least 12, and water.
A second embodiment of the present invention is directed to a method for sterilizing medical and dental instruments and hard surfaces which comprises contacting the medical or dental instruments or hard surface with an aqueous disinfecting solution comprising an alkali metal or alkaline earth metal hypochlorite, an amount of a base sufficient to raise the pH of the solution to at least 12, and water, for a time sufficient to disinfect the medical or dental instruments or hard surface.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is directed to an aqueous disinfectant solution which comprises an alkali metal or alkaline earth metal hypochlorite, an amount of base sufficient to raise the pH of the solution to at least 12, and water. The disinfectant solution according to the present invention allows for the rapid and effective sterilization of medical and dental instruments and hard surfaces, without corrosion of metal or damage to plastic, optical fibers or glass.
The active ingredient in the aqueous disinfectant solution is an alkali metal or alkaline earth metal hypochlorite. Preferably, the active ingredient is an alkali metal hypochlorite. More preferably, the alkali metal hypochlorite is sodium hypochlorite.
Sodium hypochlorite is commercially available from sources such as Sigma®. A particularly preferred sodium hypochlorite is commercially available from Amuchina, Inc. under the name AMUCHINA®. AMUCHINA® sodium hypochlorite is an electrolytic chloroxidizer which provides 11 grams of chlorine per liter. The use of AMUCHINA® electrolyte chloroxidizer in the present invention is particularly preferred on account of the high purity with respect to metal content and increased stability of the active agent in AMUCHINA® electrolytic chloroxidizer as compared to other commercially available sodium hypochlorites.
The amount of alkali metal or alkaline earth metal hypochlorite employed in the aqueous disinfectant solution according to the present invention can be the minimum amount needed to show a positive disinfecting effect in any of the known methods for determining disinfecting capacity, such as standard bacteriological challenges, or such higher concentrations as may be appropriate. In general, any amount which elicits disinfecting effects is appropriate. The amount of hypochlorite employed is preferably sufficient to provide a concentration of available chlorine within the range of 225.0 to 287.5 parts per million. When sodium hypochlorite is employed in the aqueous disinfectant solution, 0.0225 to 0.0288 grams of sodium hypochlorite (as available chlorine) are preferably used per 100 milliliters of solution.
According to the present invention, the aqueous disinfectant solution also contains a base. The base may be any of the known compounds which cause an aqueous solution to have an alkaline pH, i.e., a pH greater than 7. Suitable bases are readily available from commercial sources, such as Sigma®. Preferably, the base employed in the aqueous disinfectant solution is an alkali metal or alkaline earth metal base. Particularly preferred are the alkali metal and alkaline earth metal hydroxides. Most preferred is sodium hydroxide.
The amount of base employed in the aqueous disinfectant solution is at least the minimum amount of base sufficient to raise the pH of the solution to at least 12. Preferably, the amount of base employed is sufficient to raise the pH of the aqueous disinfectant solution to within the range of 12 to 13. When sodium hydroxide is employed as the base, 3.6 to 4.4 grams of sodium hydroxide are preferably used per 100 milliliters of solution.
A preferred embodiment of the present invention comprises: 0.0225 to 0.0288 grams of sodium hypochlorite (as available chlorine), 3.6 to 4.4 grams of sodium hydroxide, and purified water sufficient to make 100 milliliters. A particularly preferred embodiment comprises: 0.025 grams of sodium hypochlorite (as available chlorine), 4.0 grams of sodium hydroxide, and purified water sufficient to make 100 milliliters.
In addition to the alkali metal or alkali earth metal hypochlorite and the base, the aqueous disinfectant solution may also contain conventional pharmaceutical additives and excipients. Preferably, the aqueous disinfectant solution also contains sodium chloride. One skilled in the art is able to determine the amount of any additives or excipients based on the intended use. For example, 100 milliliters of the aqueous disinfectant solution according to the present invention preferably also contains 0.35 to 0.45 grams of sodium chloride.
A preferred embodiment of the present invention comprises: 0.0225 to 0.0288 grams of sodium hypochlorite (as available chlorine), 3.6 to 4.4 grams of sodium hydroxide, 0.35 to 0.45 grains of sodium chloride, and purified water sufficient to make 100 milliliters. A particularly preferred embodiment comprises: 0.025 grams of sodium hypochlorite (as available chlorine),
Amuchina International, Inc.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Pak John
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