HYPERTONIC AQUEOUS SOLUTIONS OF POLYBASIC ACID SALTS

Abstract: The present invention relates to simple salt solutions of one or two polybasic acids with at least three acid functionalities having a pH between about 1.0 and 3.0 and an ionic strength exceeding 5 mu . The solutions of the present invention are useful for a number of applications, including, but not limited to, use as a cold sterilant, disinfectant, and antiviral agent.

Description: HYPERTONIC AQUEOUS SOLUTIONS OF POLYBASIC ACID SALTS Background 1. Field of the Invention The present invention relates to novel simple salt solutions of one or two polybasic acids with at least three acid functionalities having a pH between about 1 and 3 and an ionic strength exceeding 5μ. The novel solutions of the present invention are useful for a number of applications, including, but not limited to, use as a cold sterilant, disinfectant and antiviral agent. 2. Description of the Background Low pH acidic compositions consisting essentially of combinations of strong inorganic acids and weaker organic acids and having an overall pH of less than 2 have been described as being suitable for use in various pharmaceutical, biomedical and industrial applications (U.S. Patent 5,512,200, 1996, and cited patents therein). These compositions are described as multicomponent solutions of acids having a range of dissociation constants, thereby allowing for the formation of conjugates between the strong acids and the relatively weak acids. These multicomponent solutions typically contain four acids or more. In addition to requiring a multiplicity of components, these compositions also appear to require an exceptionally low pH to be effective in many of the claimed applications. As a result of the complexity of the compositions and their exceptionally low pH requirement, their utility is limited. Summary of the Invention The present invention overcomes the limitations of existing formulations and provides for simpler solutions with a broader pH range useful in a number of tailored applications. Such solutions are more effective than conventional solutions, at least in part, as a result of controlled use of their hypertonicity. More specifically, the present invention is directed to simple salt solutions containing one or two polybasic acids with at least three acid functionalities. The solutions of the invention have a pH between about 1.0 and 3.0 and an ionic strength exceeding 5μ. These solutions are useful for a number of applications, including, but not limited to, use as a cold sterilant, disinfectant, or antiviral agent. Accordingly, one embodiment of the invention is directed to a hypertonic aqueous solution containing one or two polybasic acids and a base. The acids each have at least three acid functionalities per molecule. The base is added in an amount sufficient to at least partially neutralize the solution to achieve a pH of between about 1 to about 3 and an ionic strength of at least 5μ. Another embodiment is directed to a method for inhibiting viability of biological organisms, such as bacteria, virus or fungus, on a surface comprising contacting the surface with an aqueous solution according to the invention for a period of time effective to sterilize, disinfect or otherwise inhibit the viability of the biological organisms on the surface. Other embodiments and advantages of the invention are set forth in part in the description which follows, and in part, will be obvious from this description, or may be learned from the practice of the invention. Description of the Invention The present invention is directed to hypertonic aqueous solutions of polycarboxylic acid salts, and more specifically, to hypertonic aqueous solutions of one or two polybasic acids with three or more acid functionalities per molecule that are partially neutralized with an inorganic or organic base to achieve a pH between about 1 to about 3 and an ionic strength of more than 5μ. The one or two polybasic acids may be selected from the group consisting of phosphoric acid, citric acid, isocitric acid, polyacrylic acid, an N-succinylated chitosan, hyaluronic acid, alginic acid, and carboxymethyl cellulose. In a preferred embodiment, the solution of one or two polybasic acids and a base is a mixture of citric acid or phosphoric acid, partially neutralized with an inorganic base. For example, one preferred composition uses only citric acid and a base, such as zinc oxide. Another preferred solution is a mixture of phosphoric acid and a base, such as zinc oxide. The latter is particularly useful as a cold sterilant. Other preferred compositions are based on a mixture of both citric and phosphoric acids and a base, such as zinc oxide. In a preferred embodiment, the solution comprises a cationic component of the salt. The cationic component is preferably a monovalent cation such as Na * and K + or a divalent cation such as Mg' 2 and Zn +2 , or mixtures of them. In a preferred embodiment, the cationic component is comprised of both Na ~* and Zn 2 . Alternately, in another preferred embodiment, the solution may comprise citrate anions and Zn 12 . For example, in one preferred embodiment, the solution comprises 30 percent citric acid by weight/volume that is partially neutralized with zinc oxide. This embodiment is also particularly useful as a cold sterilant. The solutions of the present invention may be used in a number of applications, including, but not limited to, as a cold sterilant, a disinfectant, and an antiviral agent. The following examples are offered to illustrate embodiments of the invention, and should not be viewed as limiting the scope of the invention. Examples Example 1 - Efficacy Testing of Solutions Culture medium — Soil extract nutrient broth was prepared by adding one pound of garden soil to 1L distilled water. This mixture was filtered six times through Whatman #43 filter paper and then 8 grams of Nutrient broth (Difco) and 5 grams NaCl was added. The medium was boiled for 20 minutes, diluted to 1L, and adjusted pH to 6.9 with IN NaOH. This solution was filtered once more through Whatman #43 filter paper before autoclaving for 20 min. at 121 °C and 15 psi. Preparation of Suture Loop Carrier — Standard loops were prepared by wrapping size 3-0 surgical silk suture (black braided A184. USP. Ethicon, Inc.) around a pencil three times. This loop was then tied and knotted with another piece of suture before slipping off the end of the pencil. The ends of the sutures were cut to within 2mm, and prepared loops were then placed in 300 ml chloroform and incubated at room temperature for 24 hours while rotating at 100 rpm. The loops were then air-dried at room temperature under a hood. After drying, the suture loops were added to 100 ml of 0.5N HC1 and incubated for 10 minutes. After 10 minutes, loops were washed three times with distilled water (15 min. per wash) until the pH was neutral. Loops were finally dried on filter paper at room temperature for 24 hours and then sterilized by autoclave (20 min. 121 °C, 15 psi). Growth of Bacillus subtilis and Preparation of Suture Loops — A purified colony of freshly growing Bacillus subtilis (ATCC #19659) from Nutrient agar plates (Difco), was used to inoculate 500 ml soil extract nutrient broth. Inoculated medium was incubated with shaking (200 rpm) for 72 hours at 37 °C. After incubation time, culture was poured into a tissue grinder, macerated, and filtered through a sterile funnel containing moist glass wool. Approximately 10 ml of culture was added to several sterile 50 cc centrifuge tubes (NVVR) and then 10 sterile prepared suture loops were added to each 10 ml of bacterial culture. Suture loops were incubated for 15 minutes at room temperature and then removed with sterile forceps to a Petri dish lined with 2 layers of Whatman #43 filter paper. All suture loops contaminated with B. subtilis were placed in a vacuum oven at room temperature containing calcium chloride for 20 minutes, then dried under vacuum for an additional 24 hours. These loops were used within 24 hours of preparation. Verification of Spore Niability — 10 ml of2.5 Ν HCl was added to four separate sterile glass vials and five contaminated suture loops were added to each vial. After 2, 5, 10, or 20 minutes, five suture loops were transferred to thioglycolate subculture broth for 20 seconds. Each suture loop was subsequently transferred to 10 ml of fresh sterile thioglycolate broth and incubated at 37°C. Incubation was continued for a total of 21 days. Testing of Aqueous Sterilizing Agent — The following solutions, referred to as PC-1 , PC-2, and PC-3, were prepared and tested for their ability to act as an aqueous sporicidal agent. The control hydrochloric acid solutions were prepared by diluting commercial 1 ON hydrochloric acid solution with deionized water. The sterilant solutions PC- 1 , PC-2, and PC-3 were prepared as follows: ( 1 ) to prepare sterilant solution PC- 1 , solid citric acid was dissolved in deionized water at about 10% weight/volume, to produce a sterilant solution having a pH of 1.2; (2) to prepare sterilant solution PC-2, approximately 30% weight/volume solution of citric acid was first prepared by dissolving solid citric acid in deionized water, and then dissolving solid sodium hydrogen phosphate in the acid solution in small aliquots until a pH of 1.2 was achieved; and (3) to prepare sterilant solution PC-3, solid citric acid was dissolved in deionized water at 30% level weight/volume, and then small aliquots of zinc oxide were dissolved in the acid solution until a pH of 1.2 was achieved. Clean sterile vials containing 5 ml of either control or the indicated sterilant PC solution were incubated with five contaminated suture loops at 28 °C for either six or sixty minutes. At the end of each incubation time, suture loops were removed with sterile forceps and placed in 5 ml thyoglycolate broth for 20 seconds. Suture loops were subsequently transferred to 10 ml fresh thyoglycolate broth and incubated. Incubation was continued for a total of 21 days. At the end of the 21 days, the tubes were heat-shocked for 20 minutes at 80 °C and reincubated for 72 hours at 37°C. Table 1 : Effectiveness of Liquid Sterilants (PC) and Control Hydrochloric Acid Against Bacillus subtilis Spores Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The specification and examples should be considered exemplary only with the true scope and spirit of the invention indicated by the following claims. All references cited herein, including all U.S. and foreign patents and patent applications, including, but not limited to, U. S. Patent Application entitled "Multi-Purpose Acid Compositions" filed contemporaneously herewith, are specifically and entirely incorporated herein by reference. As will be easily understood by those of ordinary skill in the art, variations and modifications of each of the disclosed embodiments can be easily made within the scope of this invention as defined by the following claims.

Claims: Claims: 1. A hypertonic aqueous solution comprising: a polybasic acid having at least three acid functionalities per molecule of said polybasic acid; and a base, said base being added in an amount sufficient to at least partially neutralize said solution to achieve a pH of between about 1 to about 3 and an ionic strength of at least 5μ. 2. The aqueous solution of claim 1 wherein the pH of said solution is between about 2 to about 3. 3. The aqueous solution of claim 1 wherein the base is an inorganic base. 4. The aqueous solution of claim 1 wherein the base is an organic base. 5. The aqueous solution of claim 1 wherein the solution can be used as a cold sterilant, a disinfectant, or an antiviral agent. 6. The aqueous solution of claim 1 wherein the polybasic acid is phosphoric acid. 7. The aqueous solution of claim 1 wherein the polybasic acid is citric acid or isocitric acid. 8. The aqueous solution of claim 1 wherein the polybasic acid is polyacrylic acid. 9. The aqueous solution of claim 1 wherein the polybasic acid is an N-succinylated chitosan. 10. The aqueous solution of claim 1 wherein the polybasic acid is hyaluronic acid. 1 1. The aqueous solution of claim 1 wherein the polybasic acid is alginic acid. 12. The aqueous solution of claim 1 wherein the polybasic acid is carboxymethyl cellulose. 13. The aqueous solution of claim 1 further comprising a second polybasic acid having at least three acid functionalities per molecule of said second polybasic acid. 14. The aqueous solution of claim 13 wherein the polybasic acid and said second polybasic acid are selected from the group consisting of phosphoric acid, citric acid, isocitric acid, polyacrylic acid, an N-succinylated chitosan, hyaluronic acid, alginic acid, carboxymethyl cellulose and combinations thereof. 15. The aqueous solution of claim 1 further comprising a cationic component of the salt of a polybasic acid. 16. The aqueous solution of claim 15 wherein the cationic component comprises a monovalent cation. 17. The aqueous solution of claim 16 wherein the monovalent cation is Na or K' . 18. The aqueous solution of claim 15 wherein the cationic component comprises a divalent cation. 19. The aqueous solution of claim 18 wherein the divalent cation is Mg "12 or Zn 2 . 20. The aqueous solution of claim 15 wherein the cationic component comprises Na + and Zn 2 . 21. The aqueous solution of claim 1 further comprising citrate anions and Zn 2 . 22. The aqueous solution of claim 21 further comprising 30 percent citric acid that is partially neutralized with zinc oxide. 23. The aqueous solution of claim 22 wherein the solution is used as a cold sterilant. 24. The aqueous solution of claim 13 wherein the polybasic acid and second polybasic acid comprise a mixture of citric acid and phosphoric acid, partially neutralized with an inorganic base. 25. The aqueous solution of claim 24 wherein the solution is used as a cold sterilant. 26. A method for inhibiting viability of a biological organism on a surface comprising contacting said surface with the aqueous solution of claim 1 for a period of time effective to inhibit viability of said biological organisms on said surface. 27. The method of claim 26 wherein inhibiting comprises sterilizing or disinfecting said surface. 28. The method of claim 27 wherein the biological organism comprises one or more organisms selected from the group consisting of bacteria, virus and fungus.

Inventors: LINDEN CHARLES L JR, SHALABY SHALABY W, LINDEN, CHARLES, L., JR., SHALABY, SHALABY, W.
Applicants: STERICON L L C, STERICON, L.L.C.
Application year: 2000
Main classification: A61L2
IPC codes: A01N37, A01N59