WO2015082937A2

WO2015082937A2 - Composition and uses thereof

Info

Publication number: WO2015082937A2
Application number: PCT/GB2014/053624
Authority: WO
Inventors: Hendrik Christoffel ROOS
Original assignee: Hpa-Scientific; WALLIS, Naomi
Priority date: 2013-12-06
Filing date: 2014-12-05
Publication date: 2015-06-11
Also published as: GB201321693D0; TW201605490A; AR099653A1; WO2015082937A3

Abstract

The invention relates to a composition, formulation, method of manufacture and means of manufacture of medical treatment preparations of ultrapure stabilised hypochlorous acid. More particularly, the invention relates to an ultrapure stablised hypochlorous acid-based composition which is low in contaminating chlorine gas and hypochlorite ions.

Description

Composition and uses thereof

Field of the invention

The invention relates to a composition, formulation, method of manufacture and means of manufacture of medical treatment preparations of ultrapure stabilised hypochlorous acid. More particularly, the invention relates to an ultrapure stablised hypochlorous acid-based composition which is low in contaminating chlorine gas and hypochlorite ions. As such, the composition can be used as a pharmaceutical composition which has hypochlorous acid as its active pharmaceutical agent.

Background to the invention

The production of hypochlorous acid from sodium hypochlorite (or liquid bleach, as it is commonly known) is known in the art. Until recently sodium hypchlorite has been the principle form in which hypochlorous acid has been available. When sodium hypochlorite reacts with water, hypochlorous acid is formed (Equation 1):

Na+ (aq) + OCI^" (aq) HOCI + OH^": (Eq. 1)

As hypochlorous acid forms as a gas in the reaction, it quickly dissipates into the air and constantly needs to be replenished from the sodium hypochlorite solution. It also spontaneously reverts back to bleach when it reacts with the alkaline molecules in the solution. On its own, hypochlorous acid is therefore highly unstable.

According to Dakin, increased levels of hypochlorous acid can be achieved by adding boric acid to the mixture. For quite some time, this mixture, commonly known as Dakin's solution, has been used as the primary hypochlorous acid-based disinfectant in general medical applications. The mixture has a higher hypochlorous acid component than the previous formulation, due to the lowered pH of the solution which resulted from the boric acid reaction, and has greater disinfectant power. It is, though, still unsuitable as a topically applied treatment for patients due to the presence of hypochlorous acid salts (bleach) in the mixture. (Reference 9).

Another method for producing a hypochlorous acid solution comprises the step of electrolysis of a NaCI and water solution, in an electrolysis double chamber (one chamber containing the positive (Anode) electrode and the other chamber containing the negative (Cathode) electrode. Both electrodes are usually made from titanium dioxide. The electrode chambers are seperated by a permeable membrane. The following chemical reaction occurs (Equation 2):

2NaCI + 2H₂0 2NaOH + HOCI + H2 + CI2:

Eq. 2

The stability of the mixture containing the hypochlorous acid that is obtained by this method may be partly due to its acidity (pH in the order of 2.0 to 3.0) and partly due to the change in chemical structure of water molecules "clustering" around the hypochlorous acid gas molecules. A possible explanation is that the electrolysis process initiates the formation of hydrogen bonds and a partial proton transfer from hypochlorous acid to the water ring structure (Reference 10). The resulting increased level of hypochlorous acid in the mixture (over that in Dakin's solution for example) made it possible to study hypochlorous acid further, as it was less prone to dissipate into gaseous form. During this process, the hypochlorous acid mixture (called Anolyte) is retained for disinfectant use whilst the NaOH-containing mixture (called catolyte) is discarded. As indicated above, the hypochlorous acid mixture is highly acidic, in the order of pH 2.0 to 3.0. As a result, chlorine gas is formed by dissociation of the hypochlorous acid in the hypochlorous acid mixture. Chlorine gas, being a residual from the chemical reaction that occurs during the electrolysis process at the anode, reacts with water (Equation 3). CI2 + H20 HOCI + HCI

Eq. 3

Anolyte poses some risk, as the chlorine gas (which is present during the reaction and also forms from dissociation of hypochlorous acid due to the low pH) is toxic and could lead to side effects when used in medical treatments. The mixture has also been found to cause rust when in contact with metal surfaces (due to the low pH). Side effects that may occur in the presence of chlorine gas include eye, mouth and nose or upper airway irritation, lung irritation and allergies. Skin irritation is also common as well as skin allergies, nausea and vomiting when the fumes are breathed.

Other hypochlorous acid solutions have also been described in the art.

I n Wang et a I J. Burns Wounds 2007, 6, 65-79, the authors describe the preparation of stabilized solutions of hypochlorous acid in water. The bactericidal properties of the solutions are investigated. The stabilized solutions are prepared by the addition of NaOCI to a solution of NaCI in sterile water, followed by addition of dilute HCI to form the active component. The resulting solutions contain HOCI at various concentrations. It is reported that the HOCI solutions demonstrate broad-spectrum antimicrobial activity. The solutions require bleach for production and may contain bleach and hypochlorous acid salts as contaminants. They also require a buffer to maintain pH. Adding buffer can also result in the production of contaminating hypochlorous acid salts.

WO2010148004 discloses antimicrobial solutions of hypochlorous acid in water having a pH of about 4 to 6 and comprising a buffering agent. Several ranges of hypochlorous acid concentration are described and the examples describe the production of a hypochlorous acid solution using electrolysis. Again, the solutions have the disadvantage of comprising bleach molecules and needing to be buffered for stability, potentially resulting in further contamination.

WO2001103926 describes the preparation of hypochlorous acid solutions by electrolysis. An aqueous saline solution is passed over a mixture of proprietary catalysts on titanium electrodes to generate a mixture of oxidizing species, particularly hypochlorous acid. The pH level of the solution is then adjusted using a phosphate buffer. No indication is given of the concentration or purity of the resulting solutions.

CN101223885 discloses a hypochlorous acid solution of pH 4.5 to 7 and hypochlorous acid concentration of 10 to 200 ppm, as well as the use of that solution as a disinfectant. A method of preparation by electrolysis is reported in embodiment 1. It would be useful to provide hypochlorous acid solutions having improved concentrations and purity for specific uses and to have controllable methods of producing such compositions.

GB2488838 describes a hypochlorous acid solution which maintains activity for at least three months. It is also reported that the solution is stable for up to six months. The solution is buffered, potentially resulting in contamination with hypochlorous acid salts. It would be advantageous to provide hypochlorous acid solutions having similar or improved stability that do not require buffering. The effect of the pH of hypochlorous acid solutions on the efficacy of decontaminating Bacillus spores on different materials is investigated in Wood et al Lett. Appl. Microbiol. 2011, 53, 668-672. A range of hypochlorous acid solutions of different pH were prepared by adding acetic acid to bleach. It was found that bleach solutions with a pH lower than 6 were more effective and stable. It was reported that the free available chlorine levels in the bleach were most stable at pH 4.5. The solutions of this disclosure may be contaminated by bleach. It would be advantageous to provide solutions that are not based on bleach.

The inventor has developed another method to obtain hypochlorous acid in solution which allows hypochlorous acid to be manufactured in a purer form in which it is more stable in a water solution. The process generates defined and specific concentrations of ultrapure stabilised hypochlrous acid at a range of pH values and is thus an entirely controllable process. The solutions are stable, without the need for a buffer and are not reliant on bleach for their production.

Summary of the invention

The invention provides an ultrapure hypochlorous acid solution. The solution is preferably free from both of chlorine gas and hypochlorite ions. In particular, the solution preferably comprises less than 20%, more preferably less than 15%, more preferably less than 10%, more preferably less than 5% more preferably less than 1%, more preferably less than 0.5% more preferably less than 0.01% chlorine gas. The chlorine gas is preferably measured as a percentage of the total free available chlorine (FAC).

FAC is a combined form of hypochlorous acid, OCI- (hypochlorite anion) and CI2

(dissolved chlorine gas) in aqueous solution. The chlorine specification profile (which species is dominant) is represented in Fig 1 and Table 1. It can clearly be observed that lower pH values favor the presence of chlorine gas (CI2) and higher pH values favor the presence of hypochlorite ion (OCI-). The pH where hypochlorous acid is predominant and pure is at a pH level between 4.5 and 5.5. In table 1, it can also be seen that if a solution is manufactured and unaltered at a pH value of between 4.5 and 5.5, that the only FAC molecule present in the mixture is hypochlorous acid. Without being bound by any theory, the inventors believe that this manufactured pH level is made more possible by the described method of manufacture of hypochlorous acid. The manufacture of hypochlorous acid solutions through electrolysis of NaCI leads to a very low pH of the solution (pH 2-2.3). If this solution needs to be brought to a higher pH level, the composition of the mixture changes with hypochlorite being formed, an undesired contaminant for a pharmaceutical preparation and other preparations.

The % of chlorine gas in the composition is preferably the percentage of total chlorine present as chlorine gas. It may be measured with a chlorinometer, for example the HI 96771 Hanna Instruments UHR photo chlorinometer, or by any other standard method.

The composition of the invention preferably has a pH between 3.5 and 7, more preferably between 4 and 6, even more preferably between 4.5 and 5.5. The composition preferably does not contain a buffering agent to alter the pH, other than hypochlorous acid.

The composition preferably comprises hypochlorous acid at a concentration of between about 30 milligrams per litre and about 120 milligrams per litre, more preferably between about 75 to 100 milligrams per litre, e.g. about 80 milligrams per litre or 100 milligrams per litre.

In one embodiment, the hypochlorous acid is at a concentration of about 80 milligrams per litre and the composition has a pH of about 5.4 In another embodiment, the hypochlorous acid is at a concentration of about 100 milligrams per litre and the composition has a pH of about 4.5.

The composition is preferably stable for at least 3 months, more preferably at least 6 months, more preferably at least 9 months, even more preferably at least 12 months, even more preferably at 22 months as illustrated (Table IB). The composition preferably shows this stability when kept in a glass container, especially a dark glass container. It may also or alternatively show such stability when kept in a high quality dark polyethylene teraphthalate (PET) or other moisture resistant plastic container. It preferably shows such stability when kept away from sunlight. It preferably shows such stability when kept at a temperature of below 25°C.

The composition is also preferably substantially free of bleach (hypochlorite) or hypochlorous acid salts. The composition preferably comprises less than 5%, more preferably less than 2%, more preferably less than 1%, more preferably less than 0.5%, more preferably less than 0.01% bleach and/or hypochlorous acid salts, particularly as a percentage of the total FAC.

Also provided is a method for preparing an ultrapure, preferably stabilised, hypochlorous acid composition according to the invention, comprising the step of electrolysis of hydrochloric acid and water in an electrolysis chamber. The electrolysis chamber preferably contains titanium and iridium dioxide electrodes. Some advantages associated with the use of these metals include high dimensional stability and load resistance, economical energy usage, and low weight.

As mentioned above, instead of using, in a conventional fashion, water and NaCI as reactants for electrolysis, water and hydrochloric acid are used. The chemical reaction that occurs is represented by Equation 4, with the product ultrapure stabilised hypochlorous acid water. 2HCI + H20 HCI + HOCI + H2 (gas)

Eq. 4

As mentioned above, within any water solution containing hypochlorous acid, two other free chlorine species (called Free Available Chlorine or 'FAC') might potentially occur. These comprise chlorine gas (CI2) and ionic hypochlorite (OCI-). Of the FAC molecules, hypochlorous acid has the most significant potential for application as a treatment preparation and it is therefore important that in any solution that contains hypochlorous acid, the chemical environment is such that hypochlorous acid formation / concentration will be favored in comparison to the other two FAC molecules. This chemical environment has been found to be governed by the pH of the mixture. Reference in this regard is made to table 1A and Figure 1.

Table 1A. Chorine Specification Profile as a function of pH

*OCI- denotes NaOCI (Reference 12).

The various free available chlorine components (CI2, HOCI and OCI-) exist in equilibrium in water; the predominant form depends on the pH of the mixture.

When the pH is between 2.0 - 7.0 (particuarly pH 4.5 - 5.5), the equilibrium favors hypochlorous acid. As the pH falls below 4, increasing amounts of CI2 are present which evolve from solution and are lost to the solution at atmospheric pressure. At pH below 2.0, the main form is CI2.

At a pH of 7.4, hypochlorous acid and OCI- are about equal, and as the pH goes above 7.4, increasing proportions of OCI^" are present. Maximum disinfecting efficacy is achieved at pH 4.5 - 5.5, because all the chlorine is present as hypochlorous acid which is two orders of magnitude more effective as a disinfectant than OCI- (Reference 11). The electrolysis step is preferably carried out at a pH of between 3.5 and 7, more preferably between 4 and 6, even more preferably between 4.5 and 5.5.

The pH at which the synthesis method according to the invention produces hypochlorous acid as ultrapure stabilised hypochlorous acid has been found to be one that favors hypochlorous acid formation/ concentration. This process produces stabilised hypochlorous acid with little contamination with hypochlorite ion and chlorine gas, which thus represents a purer and more stable aqueous formulation of hypochlorous acid than has previously been possible to date. The product of the defined electrolysis process is preferably defined by 2HCI + H2O + electrical energy HOCI + HCI + H2 (gas),

Without being bound by the theory, it is the inventor's understanding that a secondary electrolysis reaction in which the resultant HCI is further reacted to form HOCI and H2O is permitted (below) allowing an overall reduction of HCI within the product and a greater proportion of hypochlorous acid in the solution

2HCI + H2O + electrical energy ^ HCI + HOCI + H2 (gas) (secondary electrolysis)

As more HCI is consumed in secondary reaction the higher pH of the product is maintained Hypochlorous acid is a gas and is normally lost from an aqueous solution through dispersal into the air and through dissociation into H⁺ and OCI- or reverting back into HCI and O2. The method according to which the composition of the present invention is manufactured has been found to provide a stable solution which has a shelf life as long as, if not longer than, one year after manufacture, especially if it is kept in a dark glass bottle below 25°C and away from direct sunlight. The hypochlorous acid may remain stable in this aqueous solution because of bonds between the hydrogen molecules of the hypochlorous acid and the water molecules in the mixture (Reference 10). This post-manufacturing stability is exemplified in Table IB.

Table IB

Stability of 80mg/l pH 5.5 and lOOmg/l pH4.5 Ultrapure Stabilised Hypochlorous acid under ICH conditions

(i) 80mg/l Ultrapure HOCI, pH 5.4 stored in unopened 10ml dark glass bottles with glass dropper dispenser at 25°C ±2°C and 60% ±5% Relative Humidity (RH), 30°C ±2°C and 65% ± 5% RH and 40°C ±2°C and 75% ± 5% RH for up to 22 months (Batch 021012805.4). (ii) lOOmg/l pH 4.5pH 4.5 stored in unopened 10ml dark glass bottles with glass dropper dispenser at 25°C ±2°C and 60% ±5% Relative Humidity (RH), 30° C ± 2° C and 65% ± 5% RH and 40° C ± 2° C and 75% ± 5% RH (Batch 0210121004.5.4)

(i) MONTH PPM PH

25C 30C 40C 25C 30C 40C

0 82 5.4

3 81 80 81 5.5 5.5 5.5

6 77 78 79 5.5 5.5 5.5

9 80 79 80 5.4 5.4

12 80 80 5.4 5.4

15 78 5.5

19 77 5.6

22 74 5.7

25

(ii)

As mentioned above, it is important that the hypochlorous acid solution is generated at the correct pH. This is possible using a standard electrolysis chamber such as a RECTIFY-240 machine. Using such a machine, the inventors have found that it is possible to manufacture 80 mg/litre (range 75 - 85 mg/litre) hypochlorous acid at pH 5.5 (range 5.4 - 5.6), at 110 liters per hour. Further concentrations and other pHs within the desired ranges can also be produced consistent with the values in Figure 1. However in addition to the ability to generate ultrapure stabalised solutions of hypochlrous acid which are conistant with those cited in Figure 1, the unique control of electrode current and the flow rate of reactants (which mediate the time in the electrolysis chamber), this innovative method of production can generate identical concentrations of aquous ultrapure stabilised hypochlorous acid at different pH values. In similar different concentrations are possible at different pH values exemplifying the control within the process. Table 1C. Alterations in conditions which effect water reactant flow rate (psi, pressure used to drive flow) and electrical current across the electrodes allows full control of the process and allows a range of aqueous ultrapure stablised hypochlorous acid concentrations at specific pH values to be generated.

Conditions under which different pH values give rise to identical concentrations of aqueous ultrapure stabilised hypochlorous acid are in bold, and conditions where identical pH values give rise to different conentrations of aqueous ultrapure stabilised hypochlorous acid are underlined. Situations where different electrical current and flow rates of reactants (conditions) give rise to identical concentrations of aqueous ultrapure stabilised hypochlorous acid are double underlined

1 .50Amps Ppm 1 18 1 1 1 109 103

PH 3.4 3.7 3J 4.1

Litres/h 85 100 1 10 120

It is not possible to produce hypochlorous acid of an appropriate pH using the prior art manufacturing methods. For example, an electrolysis process that makes use of a brine solution, (like sodium chloride) to manufacture hypochlorous acid inevitably results in the manufacture of highly acidic (pH 2.0 - 3.0) hypochlorous acid which is too acidic for therapeutic use. At such a low pH, there is a significant (up to 30%) presence in the solution of chlorine gas, which can produce toxic side-effects like lung, skin and eye irritation when in contact with human tissues. In order to achieve a more favorable pH where chlorine gas is not present in the solution, the solution needs to be buffered chemically. By buffering the highly acidic mixture of hypochlorous acid, the salts of hypochlorous acid, which form as a result of the buffering process, will be present in the mixture. The most common salts of hypochlorous acid, which results from the buffering of highly acidic hypochlorous acid, are sodium hypochlorite (liquid bleach) and calcium hypochlorite (solid bleach), both of which are undesirable in a topical treatment formulation for a product used to treat human skin and particularly human eyes. Their presence is associated with the development of side effects like eye or skin irritation, sensitivity, allergic reactions and lung irritation.

It should also be noted that the most commonly known method of electrolysis of water using sodium chloride produces not only a highly acidic mixture (anolyte) of hypochlorous acid and chlorine gas but also one in which the concentration of the hypochlorous acid is usually high (140 - 2500 mg/litre). Too high a concentration of hypochlorous acid can irritate human tissues. Simply diluting the resulting mixture of hypochlorous acid and chlorine gas to reduce the concentration does not change the pH of the mixture. In fact, the dilution necessary to reduce the concentration of hypochlorous acid to avoid toxicity (this could be in the order of 1:500 dilution) is such that the concentration of hypochlorous acid in the diluted mixture will become too low and ineffective. Such small concentrations of hypochlorous acid solution have been found to be ineffective for the treatment of bacterial conjunctivitis (See Figure 5). For example, if an anolyte mixture of 1000 mg/litre of hypochlorous acid/Cl2 mixture is diluted by a factor of 1:500, the concentration of hypochlorous acid will only be 2 mg/litre of hypochlorous acid/Cl2 mixture. The pH of the mixture is still very low, there will still be chlorine gas present in the mixture, which, if used, will cause tissue irritation (see Figure 5).

Another common method of manufacturing hypochlorous acid is by using sodium hypochlorite and then bringing the pH down from a very alkaline (around pH 10.0 - 12.0) level to pH 5.5, using hydrochloric acid. (Equation 5):

NaOCI + 2HCI NaCI + HOCI, followed by

HOCI + HCI H2O + CI2 Eq. 5

The problem with this process is that not only is an amount of chlorine gas formed and lost through this chemical reaction, but the end product is unstable and constantly varies between hypochlorous acid, salt (sodium chloride), chlorine gas and unconverted bleach, depending on the pH of the mixture. Pure hypochlorous acid on the other hand, as is manufactured using the method of the invention, does not need to be buffered or changed otherwise to reach the desired concentration, pH, purity and stability.

The electrolysis reaction of the invention, as shown in equation 4 may be carried in a reaction mixture of the hydrochloric acid and water. It may, in particular, carried out in the presence and with the operational assistance of a cathode and an anode that are at least partly immersed in the reaction mixture and between which an electrical current passed to drive the electrolysis reaction. The reaction mixture preferably comprises, as reactants, only the hydrochloric acid and water. The anode and the cathode may, in particular, be of titanium and may be coated with iridium dioxide.

The electrical current driving the electrolysis reaction may be at an amperage of between about 0.5 amp and about 3 amp, more particularly between about 1 amp and about 1.7 amp, e.g. at about 1.40 amp. A current of such magnitude may therefore, in use, be passed between the electrodes, at least when they are at least partly immersed in the reaction mixture.

The electrolysis reaction of equation 4 may be carried out in an electrolysis reaction stage. The stage may comprise an electrolysis reaction vessel. Using 'electrolysis reaction stage' and 'electrolysis reaction vessel' interchangeably, the hydrochloric acid and the water would preferably be fed continuously into the reaction vessel to provide, at steady state, a steady volume of reaction mixture in the reaction vessel whilst the electrical current is continuously passed between the anode and the cathode such that the electrolysis reaction is driven and takes place continuously in the reaction vessel and such that treatment preparation formed through the electrolysis reaction can be continuously withdrawn from the reaction vessel. Residence time of the reaction mixture and the magnitude of the steady volume of reaction mixture in the reaction vessel may therefore be controllable by varying flow rate through the vessel. Thus the reaction is controlled by the water flow rate, the hydrochloric acid flow rate and electrical current passed, and as such the precise product specification is controlled by the reaction time within the electrolysis vessel at the pre-specified electrode amperage. The hydrochloric acid, as reactant, may be in aqueous solution. Typically, the concentration of the hydrochloric acid in such a case may be between from about 4.5% to about 9%, e.g. about 4.5%, about 6% or about 9%, and more specifically 6% These concentrations may be as measured by a hydrometer measuring the specific gravity (SG) of the solution. Conventionally, this is done using a standard chart of the specific gravity of different concentrations of hydrochloric acid that provides the specific gravity of different concentrations of hydrochloric acid at different temperatures. For example, at 20 degrees centigrade, the SG of 4.5% HCI is 1.02055, that of 6% HCI is 1.02790 and that of 9% HCI is 1.04250.

Preferably, the hydrochloric acid is chemically pure, food grade hydrochloric acid. In this form the hydrochloric acid may be virtually absent of contaminants, such as metals, or metal-based substances, and toxic substances like arsenic. The water used as the reactant, may be tap water, for example may comprise chloride, calcium, fluoride and phosphates. An example of the water used in the process had a composition of choride 8mg/l, dissolved calcium 2.5mg/l, fluoride 0.1mg/l, orthophosphate <0.1, pH 7.0]. Alternatively, the water may be purified water as presented as distilled or via reverse osmosis. The water preferably comprises less than 2.5mg/l calcium and/or less than 0.1mg/l phosphate. Since the product of the reaction is predominantly hypochlorous acid with little HCI, it is the hypochlorous acid that would be the major buffering agent within the solution. Water with high dissolved levels of calcium and phosphate would potentially consume hypochlorous acid resulting in a reduction in effective concentration of hypochlorous acid. Preparation of ultrapure stabilised hypochlorous acid using municipal water with a low calcium (Table ID (i)) and orthophosphate content results in a stable product at 45 days post manufacture (Table ID (ii)) whereas water extracted from a dolomitic borehole source which had higher levels of dissolved calcium and orthophosphate (Table ID (i)) gave rise to a solution which had reduced stability when assesed at 54 days post manufacture (Table ID (ii)) Table ID. (i) Composition of water from municipal and dolomitic borehole sources and (ii) stability of lOOmg/l aqueous ultrapure acid hypochlorous prepated using either municipal (low calcium and phosphate) or dolomitic borehole derived water (high calcium and phophate after storage in dark glass bottles for 45 days

(i)

As such the specification of the water to be used in the process preferably has dissolved calcium levels of <2.5 mg/L and <0.1mg/L orthophosphate and is at a neutral pH.

In manufacturing a hypochlorous acid treatment preparation according to the invention having a particular set of desired properties within the parameters defined above for the treatment preparation, the hydrochloric acid reactant, typically in aqueous solution as provided for above, is added to the water reactant at a predetermined rate, thereby providing the reaction mixture. Preferably, the addition of the hydrochloric acid to the water is computer-controlled. An electrical current of predetermined magnitude is then passed between the two electrodes, being at least partly immersed in the reaction mixture, and drives the electrolysis reaction of equation 4. The current is preferably direct. Passing the electrical current between the electrodes is also, preferably, computer controlled. As the conductivity of the bulk reactant mixture may vary due to the exact quantity of HCI in the solution inside the electrolysis chamber at any given moment, the computer varies the electrical current to comply with the input values. For example the set current value may be 1.4 amp, but the actual current may vary between 1.35 and 1.45 amp if the flow rate of HCI is slightly higher or lower at a specific moment. In adjusting the properties of the ultrapure stabilised hypochlorous acid solution, i.e. the product, any of the electrical current magnitude, water flow rate and hydrochloric acid flow rate may be adjusted, or varied, being maintained constant for a particular set of desired properties. As alluded to above, varying the flow rate of water through the reaction vessel would typically vary the residence time that any discrete volume of water is present inside the electrolysis chamber. Whilst not wishing to be bound by theory, the applicant believes that the longer discrete volumes of water take to pass through the electrolysis chamber, the more time is available for the electrolysis and secondary electrolysis reaction to occur. Accordingly, by reducing water flow rate through the electrolysis chamber while keeping the current flow across the electrodes constant, a higher concentration of hypochlorous acid may typically be achievable in the resulting hypochlorous acid solution, with lower levels of contaminating HCI in the product. The faster the water flow rate is, the less time there may be for the electrolysis reaction to take place and therefore the lower the concentration of hypochlorous acid in the resulting hypochlorous acid solution may be. It is believed that by varying the water flow rate, the concentration of hypochlorous acid in the hypochlorous acid solution may typically be varied between about 20 and about 120 mg/litre.

It is further demonstrated, also without wishing to be bound by theory, that by varying the flow of hydrochloric acid through the chamber, the pH of the final hypochlorous acid solution can be varied. For example, for a 6% hydrochloric acid feed solution, a water flow rate of 85 litres per hour, and an acid flow rate of 5 pump strokes per minute (2 ml per minute of the 6% hydrochloric acid - generally in this specification one pump stroke equals 0.4 ml of hydrochloric acid solution), the pH of the solution has been found to be about 6.3. When the flow rate of hydrochloric acid is, in such a case, increased to 10 strokes per minute, the pH has been found to reduce to about 5.9. As will be appreciated therefore, by selectively increasing or decreasing respectively the hydrochloric acid flow rate for a particular current magnitude, voltage difference and water flow rate, the pH of the resulting hypochlorous acid solution may be selectively respectively decreased and increased.

It is further believed, still without wishing to be bound by theory, that the concentration of hypochlorous acid in the hypochlorous acid solution may also be varied by increasing or decreasing the amperage, i.e. electrical current flow, between the electrodes. However, using this method to control the concentration of hypochlorous acid is regarded as being less desirable since there is a limit to the amperage, due to the potential for overheating the power supply to the electrolytic chamber.

The potential difference, i.e. voltage, between the electrodes may typically be up to about 19 volts. When the hypochlorous acid solution is required at a rate of between about 85 and about 100 litres/hour, the voltage may be between about 17 and about 19 volts, e.g. about 18 volts and at a current of about 1.4 amps. In continuous manufacture, water flow through the reaction vessel may be at a predetermined water flow pressure from about 18 psi to about 26 psi, e.g. at about 22 psi. HCI feed into the electrolysis chamber may, for a treatment preparation output volume of about 85 litres per hour be at between about 1 and about 10 pump strokes per minute, e.g. about 5 pump strokes per minute, with each pump stroke being about 0.4 ml. The pulse width of the pump strokes may be between about 50 milliseconds (ms) and about 300 ms, e.g. about 170 ms. Further provided is a pharmaceutical composition comprising the hydrochlorous acid composition of the invention. The pharmaceutical composition may be provided in any appropriate form for administration to a subject. For example, it could be in the form of a spray, an eye drop or any other appropriate form. Also provided is a wound dressing, gauze or the like comprising a hydochlorous acid composition according to the invention.

Also provided is a hydrochlorous acid composition according to the invention for use in therapy. The composition may be used for treating a number of different undesired conditions, as discussed below. The invention further provides a method of treating an undesired condition, comprising administering the hydrochlorous acid composition of the invention to a subject in need thereof.

Undesired medical conditions that may be treatable with hypochlorous acid may include an undesired ocular condition, an undesired skin condition, an undesired dental condition, a skin and/or flesh wound, and grey hair. Accordingly, the affected areas on the subject may be an ocular area, a skin area, a flesh area and an area where there is grey hair.

The undesired ocular condition, or ailment, may be at least one of an ocular injury, an ocular infection, a condition of increased pressure inside the eye, degenerative conditions of the retina and optic nerve, and/or a cataract. The term cataract is meant to include within its scope clouding of the lens of an eye.

By "ocular injury" is meant, generally speaking, a disruption of the conjunctiva, corneal or scleral surfaces of an eye. Naturally, the disruption can occur at different depths into the corneal or scleral surfaces.

By "ocular infection" is meant, generally speaking, contamination of the conjunctiva (including the lids), cornea and/or sclera. Such contamination may be by reason of, for example, bacterial and/or viral and/or fungal infection.

The ocular area that may be treated with the treatment preparation may, therefore be the cornea, the anterior chamber, the lens, the posterior chamber, the retina, the choroid, typically inclusive of the optic nerve, and/or the sclera of an eye that is affected by the undesired medical condition. The choroid is the pigmented vascular layer of the eyeball between the retina and the sclera.

By "administration" and "effective amount", in the sense of an undesired ocular condition, is meant in the order of, preferably specifically, two drops of treatment preparation solution per eye Two drops of eye treatment solution equals 0.1 ml. A typical, and, in fact, a preferred administration frequency may, at first, be every 5 minutes for one hour, followed by every two hours for two days, followed by 3 times per day, e.g. at 07.00, 17.00 and prior to sleep. Whilst it is preferred to apply the treatment preparation solution as a drop- dispensed product, the treatment preparation may also, typically in the case of severe sensitivity of the eye, be applied in the form of a spray-dispensed product which allows for application of the treatment preparation solution as fine mist spray. In other words, administration may be by introducing the treatment preparation into the eye drop-wise, or by spraying the treatment preparation into the eye. When the treatment preparation is applied in the form of a spray, the spray bottle should preferably be kept between about 10 and about 12 cm from the eye and two pumps of the spray should be dispensed onto the open eye and over the eyelids. Preferably, in the case of ocular infection both eyes of the subject are treated at the same time, regardless of whether or not both eyes are known to be affected, thereby preventing or limiting the undesired eye condition from spreading to the potentially unaffected eye. The regulation of normal bacterial flora contributes to periodontal (the area around the implantation of the teeth into the jawbone) health, and hypochlorous acid seems to have the ability to attack Gram-negative pathogens during periodontitis.

Periodontitis is an inflammatory process initiated by plaque biofilm that leads to loss of periodontal attachment to the root surface and adjacent bone, and which ultimately results in tooth loss. Destruction of periodontal tissue in periodontal disease is caused by an exaggerated response to certain disease forming bacteria. Thus, the control of these bacteria and the stimulation of the healing process, together with the destruction of biofilm and the suppression of inflammation are central to controlling periodontal disease.

Halitosis (bad breath) is caused, amongst others, by the accumulation of gas-forming pathogenic bacteria in the mouth, especially on the tongue. By eradication these bacteria, a significant improvement can be obtained.

Method of use: Gargle with 30 ml hypochlorous acid of a 80 mg/litre pH 5.4 concentration hypochlorous acid three times per day. Firstly rinse the mouth with 30 ml hypochlorous acid to rid the mouth of excess (alkaline) saliva that may neutralize the hypochlorous acid. Immediately after gargle, the mouth is rinsed thoroughly for 1 minute using repeated doses of 30 ml hypochlorous acid. Undesired skin conditions may include acne, rosacea, impetigo, cellulitis, fungal infections of the skin (e.g but not limited to tinea pedis, pityriasis versicolor, tinea versicolor and candidiasis), viral infections of the skin (e.g. but not limited to herpes fever blisters and zoster), nappy rash, psoriasis, eczema and pigmentation disorders of the skin, including post inflammatory hyper pigmentation (PIH). Nappy rash could comprise of a combination of properties, e.g. inflamed, irritated skin, chemically burned skin, and infection.

Administering the treatment preparation (HOCI 100 mg/L pH 4.5) may, in treating acne, include wetting the affected skin area with the treatment preparation. Such wetting may typically be by spraying the treatment preparation onto the skin using an atomizer pump. It is expected that approximately 10 to 15 sprays will effectively wet the skin. Administration may also include the prior step of washing the face twice per day with a liquid cleanser, preferably not containing soap as it may raise the pH of the skin due to its alkaline nature. An alkaline surface pH on the skin will neutralize the hypochlorous acid and make it ineffective, or at worst change the hypochlorous acid into its salt, which is sodium hypochlorite, (bleach). This might have negative effects on the skin in the form of allergic reactions, hypersensitivity or skin irritation. Preferably, the skin is dried prior to application of the treatment preparation. After application of the treatment preparation, the skin is preferably allowed to dry naturally.

In relation to other undesired skin conditions, administering the treatment preparation may include wetting the affected skin area with the treatment preparation. Such wetting may also be effected by way of spraying using an atomizer spray pump. Typically, administration may occur 4 times per day. Spraying should preferably be effected 10 to 15 cm from the skin and in sufficient quantity thoroughly to wet the skin. The skin should then preferably be left to dry naturally. In the case of nappy rash, administration may be effected after each nappy change. Skin and/or flesh wounds may include burns of any depth into the skin, e.g. epidermis, superficial dermis, up to and including hair follicles and deep skin where the burn wound extends further than the hair follicles. Skin and/or flesh wounds may also include pressure sores, chronic wounds, diabetic ulcers, elective surgery wounds, including but not limited to abdominal surgery wounds, thoracotomy wounds, gynecological wounds, plastic surgery wounds, ear nose and throat surgery wounds, orthopedic surgery wounds and stoma therapy wounds. Chronic wounds are classified as from venous stasis or any other form of lack of blood supply. These wounds classically but not only occur in the lower leg and may be present for many years.

Administering the treatment preparation to skin and/or flesh wounds may include applying the treatment preparation onto the fresh wound intra-operatively and spraying of the wound through a atomizer spray three times per day postoperatively, as soon as surgical dressings, if applied, have been removed. Such administration would typically be continued for about three weeks after surgery, or closure of the wound, and then twice per day for another month. Administering the treatment preparation in the case of elective surgery wounds may include irrigating the wound with copious amounts of the treatment preparation as an irrigation fluid and then leaving the irrigation fluid inside the wound for between about 3 and about 5 minutes before closing the wound. If suction drainage is used, administration may include inserting a drain, but not activating the drain for a period of about 3 to about 5 minutes. Thus, sufficient contact time between the treatment preparations and the wound is allowed.

The composition may also be used to treat grey hair. Administration may include applying the treatment preparation to the affected area, which would typically be the scalp. Application onto the hair may then also occur. Preferably, application involves spraying the treatment preparation onto the affected area. Administration may be to such an extent as completely to wet the scalp and the hair. The affected area may then be left to dry naturally. Grey hair has been described as being caused by a build up of micro molecular quantities of H2O2 (peroxide) in the hair follicle and hair shaft. By applying hypochlorous acid to the hair, it is postulated that the (Equation 6):

HOCI + H2O2 H2O + HCI + O2:

Eq. 6 causes the peroxide to be neutralised thus preventing grey hair from forming.

Also provided is an electrolysis device for production of the composition of the invention. The device comprises at least one, preferably only one electrolysis chamber. It further comprises an inlet capable of providing a controlled flow rate of reactant into the chamber. The flow rate may be controlled by any appropriate means, such as a valve. The flow rate may preferably be controlled such that the flow rate is less than 150l/h, preferably less than 140l/h, more preferably less than 130l/h, even more preferably less than 125l/h. The electrolysis device may be provided with a sensor to monitor the flow rate. The electolysis device may also be provided with a electrical current sensor to monitor the amperage across the electrodes in the chamber. Further, the device may be provided with a means for altering the electrical current in the chamber,, so as to control the concentration of the hypochlorous acid produced.

The invention will now be described in more detail, by way of example with reference to the accompanying drawings. Brief description of the drawings

FIGURE 1 shows, for various concentrations of solutions of hypochlorous acid, the percentage of effective chlorine in the form of hypochlorous acid, hypochlorite ion and chlorine gas versus the pH of the solution;

FIGURE 2A shows, diagrammatically, typical manufacturing equipment set-up to produce a hypochlorous acid solution as treatment preparation in accordance with the invention; the set-up 10 comprises a conventional electrolysis chamber 12 suitable for producing a treatment preparation in accordance with the invention comprising a stable hypochlorous acid solution of ultrapure stabilised hypochlorous acid in water, with hypochlorous acid as active pharmaceutical ingredient.

In producing the treatment preparation in accordance with the invention, tap water or reverse-osmosed pure water, along feed line 14, and diluted chemically pure hydrochloric acid, along feed line 16, are continuously fed at a predetermined rate into the electrolysis chamber 12 to form a reaction mixture thereof in the electrolysis chamber 12. The mixture maintains, at steady state operation, a steady volume inside the electrolysis chamber 12, at least to such a level that the electrodes hereinafter described are at least partly immersed in the reaction mixture. There are two electrodes in the electrolysis chamber 12. These comprise a cathode 13 and an anode 15. The cathode 13 is a negatively charged electrode and attracts cations, i.e. positively charged ions. The anode 15 is a positively charged electrode and attracts anions, i.e. negatively charged ions. The electrodes 13, 15 are made of titanium and are coated with iridium dioxide, with a copper layer being interposed between the electrode surfaces (i.e. the titanium) and the iridium dioxide coating. The copper layer mainly serves to achieve a coherent bond between the titanium and the iridium dioxide.

FIGURE 2B Shows the configuration and operation of the RECTIFY-240 electrolysis machine used in the production of ultrapure stablised hypochlorous acid

FIGURE 2C Shows a Caleffi 536 pressure reducing valve Figures 3 to 16 show the treatment effect of the hypochlorous composition of the invention on a variety of conditions.

FIGURE 3 Treatment of bacterial conjunctivitis

(A) Single patient with bacterial conjunctivitis in both eyes. Treated with (2 drops in each eye every 2 hours during the day) ultrapure stabilised hypochlorous acid. Eyes cleared and were free of symtoms after 4 days of treatment. (B) Patient with previous experience of Tobramax (topical ophthalmic antibiotic) for 3 months presenting with bacterial conjunctivitis particularly on the top lid causing invertion of the lid. Sympoms did not resolve on Tobramax and no effects on disease resolution were noted from Tobramax treatment. Eyes cleared after 3 days on treatment with ultrapure sabilised hypochlorous acid (2 drops in each eye every 2 hours during the day) and patient reported eyes as normal with complete symptomatic relief at 2 days following treatment

FIGURE 4 Treatment of bacterial conjunctivitis (additional data)

Two patients with bacterial conjunctivitis (single eye from each patient). Treated with ultapure stabilised hypochlorous acid (2 drops in each eye every 2 hours during the day). Eyes cleared and were free of symtoms after 4 days of treatment.

FIGURE 5 Dose-ranging efficacy studies in bacterial conjunctivitis patients

Dose ranging studies in cases of bacterial conjunctivitis with ultrapure stabilised hypchlorous acid (2 drops in each eye every 2 hours during the day). I n all cases where no efficacy was observed, patients were switched to the clinically best tolerated formulation (2 drops every 2 hours during the day).

FIGURE 6 Treatment of viral conjunctivitis

Single patient with viral conjunctivitis (both eyes). Treated with ultrapure stabilised hypochlorous acid ultrapure stabilised hypochlorous acid (2 drops in each eye every 2 hours during the day). Eyes showed a significant improvement in symptoms after 3 days of treatment and were completely without symtoms after 9 days of treatment. FIGURE 7 Treatment of viral conjunctivitis (additional data)

Two patients with viral conjunctivitis (single eye from each patient). Treated with ultrapure stabilised hypochlorous acid (2 drops in each eye every 2 hours during the day). Patient VCOl showed a clearing of conjunctivitis symptoms after 7 days and an improvement with coincident viral keratitis symptoms. Symptoms from patient VC04 showed a complete clearance after 3 days treatment.

FIGURE 8 Treatment of meibomianitis

(A) Two patients with meibominitis (single eye from each patient). Treated with ultrapure stabilised hypochlorous acid (2 drops in each eye every 2 hours during the day). Patient Mil presented with a history of chronic and persistant disease and showed a 95% improvement following 7 days treatment. Patient M12 prsented with a history of chronic disease lasting many years and showed a clearing of symptoms after 28 days treatment. (B) A further patient with bilateral meibomianitis with blepheritis with a history of persistant disease, showing puffy and red eye. Patient treated with 2 drops of 80mg/l hypochlorous acid per day for 3 days. After 3 days treatment lids dramatically cleared. Red eye cleared and comfort dramatically improved.

FIGURE 9 Treatment of corneal burn and corneal ulcer

Single patient with chemeical burn in single eye. Treated with (2 drops in each eye every 2 hours during the day) ultrapure stabilised hypochlorous acid. Burn showed evidence on quicker healing and showed significant improvement and had reduced symtoms. A similar impact was noted for a patient presenting with corneal ulcer. After treatment ulcer showed dramatic improvement and significant and rapid progression of healing.

FIGURE 10 Treatment of ocular herpes virus infection

Single patient with evidence of corneal ocular herpes infection. Treated with (2 drops in each eye every 2 hours during the day) ultrapure stabilised hypochlorous acid. Symptoms of infection were reduced and keratitis showed evidence of improvement and quicker healing.

FIGURE 11 Treatment of corneal laceration and scleral pterygium

Single patient with corneal laceration in single eye. Treated with (2 drops in each eye every 2 hours during the day) ultrapure stabilised hypochlorous acid. Laceration showed evidence of improvement following treatment. Patient with sclearl Pterigium also showed evidence of disease following treatment.

FIGURE 12 Treatment of abdominal sinus wound and surgical wound

Patient (top) was treated with lOOmg/l hypochlorous acid soaked gauze plug which was changed daily and irrigation of wound every 2 days with 20ml of lOOmg/l hypochlorous acid. Significant effect on wound closure was noted after 6 days. Patient (bottom) was suffering an Methocillin resistant staphalcoccus aureus (MRSA) infection of a surgical wound and was treated for 30 days with dosing every three days with lOOmg/l hypochlorous acid. At 30 days there was a significant improvement in wound closure and the wound was MRSA negative on culture.

FIGURE 13 Treatment of 2^nd degree burns

Patient was a 2 year old boy suffering a serious burn and was treated for 9 days with

8 applications of lOOmg/l hypochlorous acid sufficient to apply to the whole lesion (with the exception of the umbilicus). The wound healed more quickly than anticipated and was associated with a good healing response, without obvious signs of infection and significant reductions in both inflammation and pain.

FIGURE 14 Treatment of septic surgical wonds

Patient suffering from a significant wound infection (septic). Patient was treated with 2 doses of lOOmg/ml hypochlorous acid applied every three days. At 6 days post- treatment wound displayed a dramatic improvement in swelling and associated pain FIGURE 15 Abrasive wound

Patient suffering from a facial abrasion wound was treated with lOOmg/l hypochlorous acid twice per day for 5 days (by spraying such that wound is completely covered). Patients showed a significant improvement with clear and rapid wound healing response and absence of facial scarring

FIGURE 16 Treatment of hot oil burn

9 year old boy suffering from facial burn due to contact with hot cooking oil. Patient was treated for 6 days (3 X daily applications) with lOOmg/l (spray) Ultrapure stabilised hypochlorous acid pH 4.5. Both infection and inflammation were controlled with no "redness" or evident scarring at day 6 Detailed description of the invention

Manufacturing set-up

In Figure 2A, reference numeral 10 generally indicates a manufacturing set-up for manufacturing the treatment preparation of the invention and Figure 2B show the RECTIFY-240 electrolysis machine. In order to create a machine, noted as the RECTI FY-240, in which the flow rates of reactants and control over electrical current to the electrodes could be achieved as such that the machine was enabled to produce ultrapure hypochlorous acid, an existing electrolysis process was adapted. The adaptations were made to a Biocider BC 240 machine from Cosmic Round, Korea and were both electronic and mechanical adaptations. The BC 240 machine can best be described as a hybrid synthesis apparatus. Hybrid synthesis refers to a machine that consists of both a software control unit and a mechanical section (pumps and electrolysis chamber). This method of production of HOCI differs sharply from other electro chemical methods where a two-chamber electrolysis process is utilized. In the typical two-chamber method, one chamber contains the positive electrode (anode), the other the negative electrode (cathode). The two chambers is separated by a membrane. This two-chamber method electrolyzes salt and water and produces two products: a very acidic HOCI is formed in the anode chamber and an alkaline substance (NaOH) of similar volume is formed in the cathode chamber.

With our hybrid synthesis one chamber machine, the software is designed to monitor and control electrical and mechanical functions. These functions include:

1. The control of HCI acid flow rate to the electrolysis chamber. When the flow of HCI is interrupted, or not at the pre-defined concentration of 6% HCI, the machine shuts down. The acid flow rate to the electrolysis chamber can also be changed according the the strength and pH of HOCI product that must be manufactured and is managed by controlling the pulse rate and pulse width of the pump. The control of electrical current to the electrode inside the electrolysis chamber. The voltage is constant (18V), but the electrical current (amperage) can be adjusted. It is a general principle that an increase in a mperage results in more HOCI being formed, as well as that the pH of the product drops due to a concomitant increase in unhydrolysed hydrochloric acid (HCI) in the manufactured product.

2HCI + H2O + electrical energy HOCI + HCI + H2 (g)

The monitoring of actual current used by the electrode. Depending on the amount of HCI in the chamber at any particular time, the current could be higher or lower than the set current. This helps the program to deliver the correct average current between the positive and negative sides of the electrode.

4. Monitoring of the water supply pressure by mea ns of a digital pressure sensor (Autonics PSA-series Digital Pressure Sensor). I n the case of the unaltered BC 240, the water flow should be 240 litres per hour. The flow is kept at this rate by an aperture valve proximal to the electrolysis chamber. At least 150-psi water pressure is needed to maintain a 240-liter flow rate through the aperture valve. This pressure is maintained by means of a special supply pump from a water holding tank to the BC 240. If the water pressure drops, or the aperture becomes blocked, the result would be a drop in supply water flow rate. When this happens the digital pressure sensor will communicate with the software to sound an alarm and close all function of the machine.

The purpose of our manipulation of the functions of the machine is to allow for a higher ppm of HOCI without the concomitant drop in pH of the product. Without these alterations, the maximum concentration of HOCI that the machine ca n produce is 20 - 30 ppm, pH 5 - 6.5. The main alterations are to reduce the pressure of supply water (with resultant reduction in flow rate) through the electrolysis chamber, as well as to stop the machine from shutting down when this happens. Once the flow rate of supply water is reduced the electrical current and HCI flow rate can be adjusted to precisely tailor the finished product to be 80 - 100 ppm, pH 5.4 to 4.5. The production of a higher (80 - 100 ppm HOCI) is achieved through seconda ry hydrolysis of the HCI into HOCI. (2HCI + H2O + electrical energy HOCI + HCI + Hf(g)). This longer period of electrolysis allows for more HCI to be hydrolyzed onto HOCI. As HOCI is a much weaker acid tha n HCI, the higher ppm values of HOCI is achieved without the drop in pH.

This manipulation of the machine is three-fold: 1. I nactivation of the digital pressure sensor. This avoids that the machine shuts down when the water pressure is reduced. Setting the upper and lower limits for the pressure sensor to nil psi avoids the software from shutting down the machine.

2. The supply pressure pump is removed and the incoming water line is

connected directly to a tap (in the case of the supply water having a neutral pH) or from a RO water source. The supply pressure should be at least 30 psi. This allows enough pressure to allow the user to manipulate the water supply pressure and subsequent flow rate.

3. Between the water supply source and the inlet into the machine, a variable pressure control valve is installed. This valve (Caleffi 536 Variable Pressure

Reducing valve) can be precisely adjusted to deliver a flow of between 15 and 25 psi to the electrolysis chamber Shown in (Figure 2C).

The set-up 10 comprises a conventional electrolysis chamber 12 suitable for producing a treatment preparation in accordance with the invention comprising a stable hypochlorous acid solution of ultrapure stabilised hypochlorous acid in water, with hypochlorous acid as active pharmaceutical ingredient. In producing the treatment preparation in accordance with the invention, tap water, along feed line 14, and diluted chemically pure hydrochloric acid, along feed line 16, are continuously fed at a predetermined rate into the electrolysis chamber 12 to form a reaction mixture thereof in the electrolysis chamber 12. The mixture maintains, at steady state operation, a steady volume inside the electrolysis chamber 12, at least to such a level that the electrodes hereinafter described are at least partly immersed in the reaction mixture.

There are two electrodes in the electrolysis chamber 12. These comprise a cathode 13 and an anode 15. The cathode 13 is a negatively charged electrode and attracts cations, i.e. positively charged ions. The anode 15 is a positively charged electrode and attracts anions, i.e. negatively charged ions. The electrodes 13, 15 are made of titanium and are coated with iridium dioxide, with a copper layer being interposed between the electrode surfaces (i.e. the titanium) and the iridium dioxide coating. The copper layer mainly serves to achieve a coherent bond between the titanium and the iridium dioxide.

In use, a potential difference of up to 19 volts, depending on the output rate of ultrapure stabilised hypochlorous acid solution and the properties thereof that are desired and as hereinafter described in more detail, is applied between the electrodes 13, 15 at a direct current load of between about 0.5 amp and about 3 amp, more particularly between about 1 amp to about 1.7 amp, e.g. about 1.40 amp. Thus, chemical reaction of the hydrochloric acid and the water in accordance with the electrolysis reaction of equation 4 above, i.e. 2HCI + H₂0 ^ HCI + HOCI + H₂ (g) is driven to produce, as the treatment preparation, hypochlorous acid in aqueous solution.

The solution is withdrawn from the electrolysis chamber 12 along product line 18. For further dilution, the product withdrawn along product line 18 can, optionally, be combined with feed water that is passed along transfer line 20. The aqueous ultrapure stabilised hypochlorous acid product solution that is thus obtained, whether diluted or not, can then be directly employed as the treatment preparation of the invention in the manner that has been described in accordance with the invention.

Manufacture of exemplary ultrapure stabilised hypochlorous treatment preparations according to the present invention: Still with reference to Figure 2A, the preparation of some embodiments of the treatment preparation of the invention is described:

Settings for Production: 110 litres per hour hypochlorous acid output, 80 mg/litre at pH 5.4

(Voltage 18 V)

26 psi 2.8 ml/minute 170 ms 1.40 amps

Settings for Production: 110 litres per hour hypochlorous acid output, 100 mg/litre at pH 4.6

(Voltage 18 V)

Water input 6% HCI Acid pump pulse Electrical current pressure width

5 strokes per

minute

24 psi 2 ml/minute 170 ms 1.40 amps

Settings for Production: 120 litres per hour hypochlorous acid output, 100 mg/litre at pH 4.5

(Voltage 18 V)

Water input 6% HCI Acid pump pulse Electrical current pressure width

8 strokes per

minute

26 psi 3.2ml/minute 170 ms 1.45 amps

Adjustment of hypochlorous acid solution properties

The applicant has found that the reaction of Equation 1, and therefore the strength of the ultrapure stabilised hypochlorous acid solution (mg/litre) and the pH of this solution (i.e. the product solution), can be adjusted by adjusting the following parameters:

1. amperage across the electrodes in the electrolysis chamber 12; 2. hydrochloric acid delivery flow rate to the electrolysis chamber 12; and/or

3. water flow rate through the electrolysis chamber 12.

It is noted that the rise in hypochlorous acid concentration is not accompanied by a significant drop in pH. Without wishing to be bound by theory, the applicant believes that the reason for the pH not dropping more significantly is that more hydrochloric acid is converted during the longer period of transition through the chamber, considering that the flow of water is the residence time-determining step. As hydrochloric acid is a far stronger acid than hypochlorous acid, the pH of the manufactured product does not change significantly when a lower acid flow rate through the chamber is used as a method to increase the concentration of hypochlorous acid.

Measurement of the ultrapure stabilised hypochlorous acid concentration was done using a photo chlorinometer and the pH was tested with a digital pH meter. More particularly, a HI 96771 Hanna Instruments UHR photo chlorinometer and a Hanna Instruments HI 98127 splash proof pH tester were used.

The effects of varying hydrochloric acid flow rate, varying water flow rate and varying current magnitude, respectively, were determined in further cases in which,

(i) the water flow pressure and hydrochloric acid flow rates were maintained constant respectively at 26psi and 5 X 0.4ml pump strokes per minute at a pulse width of 170ms, whilst the current magnitude was varied;

the current magnitude and hydrochloric acid flow rates were maintained constant respectively at 1.30 amps and 5 X 0.4ml pump strokes per minute at a pulse width of 170ms, whilst the water flow pressure was varied; and

the current magnitude and water flow pressure were maintained constant respectively at 1.30 amps and 24 psi whilst the hydrochloric acid flow rate pump strokes was varied, maintaining a constant pulse width of 170ms.

The results are shown in tables 2 to 4:

Table 2: Results of case (i)

Table 3: Results of case (ii)

Table 4: Results of case (iii)

Storage and usage in case of ocular application

For use as a treatment agent in ocular applications, the solution/treatment preparation may be kept in a dark glass bottle or high quality dark PET bottle for application by using a drop dispenser or spray.

In the case of ocular treatment, a preferred treatment regime is:

• Drop dispenser: Initially every 5 minutes for one hour, followed by every two hours for two days, followed by 3 times per day, e.g. at 07.00, 17.00 and prior to sleep. • Spray: The spray nozzle is held at 10 - 12 cm from the eye and two pumps of the spray should be dispensed onto the open eye and over the eyelids, on the same treatment period as for the drop dispenser. Ideally a spray volume of 0.05ml/spray equating to a single eye drop dose. The ultrapure stabilized hypochlorous acid solution appears unstable when stored in plastic containers and the concentration diminishes as a function of time when stored in plastic. This is not evident when ultrapure stabilized hypochlorous acid is stored in dark glass bottles, including blue and brown glass.

CLINICAL STUDIES

Human subjects with the treatment preparation according to the invention were studied in respect of various conditions in the eye and additional woundcare cases. Of these 204 were, ophthalmic patients and the improvement noted with treatment with 80 mg per litre hypochlorous acid at pH 5.5 are shown in Table 5:

Diagnosis C<i$e$ Improvement

2. Viral conjunctivitis 14 cases Number of responders

experiencing efficacy effect = 14/14

3. Meibomianitis and blepharitis 17 cases Number of overall responders

(overlap with bacterial conjunctivitis patients) 15/17 with one partial response.

Number of responders returning after 3/4 days post-treatment experiencing >90% clearing =5/5. Of 8 patients (>2 weeks disease), which presented with chronic or non-resolving disease, 7 experienced improvement within 3-28d and one on annual assessment.

4. Allergic conjunctivitis, including allergic conjunctivi tis 19 cases 85% cleared in 7 days from contact lens use 95% cleared in 14 days

99% cleared in 30 days

5. Scleral conjunctivitis 9 cases 85% cleared in 3 days

99% cleared in 7 days

100% cleared in 14 days

6. Corneal keratitis and corneal ulcers 8 cases 85% cleared in 3 days

99% cleared in 7 days

100% cleared in 14 days

7. Corneal lacerations and foreign bodies 10 cases 85% cleared in 3 days

99% cleared in 7 days

100% cleared in 14 days 8. Corneal viral keratitis (severe) 5 cases 80% cleared in 7 days

95% cleared in 30 days Progress in slow but constant after that

9. Meibomiam cysts and the common sty 6 cases 95% cleared in 14 days

99% cleared in 30 days

10. Scleral injuries/neo-vascularization 4 cases Total recovery

11. Optic atrophy 3 cases Visual improvement in 30 days.

Too early for real assessment.

12. Intra ocular hypertension 1 case Ocular pressure normal after 14

days

13. Cataract reversal 43 cases Stage 1 cataract: Very good prognosis with complete revision Stage 2 cataract: Very good prognosis with 2 lines improvement in vision.

Stage 3 cataract: 1-2 lines of improvement in vision.

Stage 4 cataract: Poor prognosis

14. Macular degeneration 11 cases Vision 6/12 and better: condition stabilized in 3 months

At 6 months, vision improves between 1 and two lines.

Patients report always an improvement in vision clarity.

15. Vitreous floaters 4 cases No significant data

16. Corneal acute viral endothelitis 1 case Significant recovery after ql

month of treatment Table 5: Improvements noted in clinical tolerability and efficacy studies

Before and after patients were treated, the following examinations were done:

• Full Personal details

· Fully consented

• Current glasses Rx

• Refraction - best visual acuity

• Intra Ocular Pressure Readings

• Corneal Curvature Readings, "K" readings

· Photo

• Slit Lamp examination to be sure that there are no side effects.

No side effects were noted in any of the patients. The longest any observed patient was on continuous hypochlorous acid treatment in accordance with the present invention was 6 months.

Visual observations of further clinical evaluations are shown in FIGURES 3 to 15, each being described below. In each case, the condition prior to treatment is shown on the left of the FIGURES with the results of treatment being shown on the right of the figure.

Treatment of bacterial conjunctivitis

Treatment of bacterial conjunctivitis (additional data)

Dose-ranging efficacy studies in bacterial conjunctivitis patients

Treatment of viral conjunctivitis

Treatment of viral conjunctivitis (additional data)

Treatment of meibomianitis

Treatment of corneal burn and corneal ulcer

Treatment of ocular herpes virus infection

Treatment of corneal laceration and scleral pterygium FIGURE 12 Treatment of abdominal sinus wound and surgical wound

FIGURE 13 Treatment of 2^nd degree burns

FIGURE 14 Treatment of septic surgical wonds

FIGURE 15 Treatment of a brasive wound

FIGURE 16 Treatment of hot oil burn

Other exemplfications (not shown in drawings) illustrate a treatment effect on cateract reversal, viral keratitis, allergic conjunctivitis, viral - superior limbic keratoconjunctivitis, macular degeneration and optic atrophy

DISCUSSION OF CLINICAL EFFECTS OF ULTRAPURE STABILISED HYPOCHLOROUS ACID

Useful exploitation of the benefits of ultrapure stabilised hypochlorous acid has, until now, not been possible, or has been limited, due to various concerns with the forms in which hypochlorous acid has, until now, been available because of contaminating chlorine gas and hypochlorite ions present in hypochlorous acid produced using known methods. The inventors have found that it is possible to prepare very pure hypochlorous acid and that such hypochlorous acid ca n be used in a variety of pharmaceutical applications. Ocular applications

Ultrapure hypochlorous acid has been found by the inventor to completely resolve severe eye and wound infections, along with the accompanying redness, swelling and pain, in as short a period as 3 days in the vast majority of patients. This is evident when the treatment preparation is externally applied. The inventor has noticed that it ta kes an average infection much longer to be resolved with the use of antibiotics: in the order of one week to ten days. I n a significant number of ophthalmic patients within our study who were re-eaxamined 3 days post-treatment a significant improvement in symptoms and patient comfort was demonstrated. I n at least one case ultrapure stabilised hypochlorous acid was effective in a patient with severe bacterial conjunctivitis which was resistent to prior treatment with the ophthalmic antibiotic tobramax (tobramycin), tobradex (tobramycin and betamethasone) and maxitrol (neomycin, dexamethasone and polymyxin B) (see Figure 3B). Naturally, in the case of ocular wounds, and any wound for that matter, the control of infection is of extreme importance to improve healing rate (see Reference 7). It is interesting to note that patients (bacterial conjunctivitis) treated with Anolyte containing 70mg/l (a lower concentration than the concentration of ultrapure stabilised hypochlorous acid used in our ocular studies), patients 4/5 showed tolerability issues (with one showing complete clearence of symptoms) and eyes remained inflamed. (See FIGURE 5, Reference 7).

Another advantage in the use of the hypochlorous acid-based treatment preparation of the invention in corneal and other wounds is that accelerated healing takes place when the treatment preparation is externally applied to the eye. This is also the case with skin conditions and general skin and/or flesh wounds. The assistance that ultrapure stabilised hypochlorous acid, as active agent, renders in this regard has been demonstrated both in vitro and in vivo. The accelerated healing is understood to be due to better control of bacterial load on the injured area and due to stimulation of an anti-inflammatory response different gene sequence than is normally the case in wounds. (Reference 13) The process of accelerated healing in the presence of hypochlorous acid is understood to be as follows: Externally applied hypochlorous acid-based treatment preparation has an effect of inducing cell proliferation and stimulates extracellular matrix component production in human fibroblasts; extracellular hypochlorous acid-based treatment preparation stimulates membrane receptors and activates kinase cascades, leading to the production of native compounds of the extracellular matrix and/or cytokines, including growth factors (see references 12,13). The result is a faster healing wound with very little scar formation in skin wounds and virtually no scar formation in healing corneas. It is postulated, without being limiting to this theory, that the lack of scar formation in the healing cornea as well as open wounds, when a hypochlorous acid-based treatment preparation is employed, could be the result of immune modulation that takes place within the healing cornea. It can therefore be appreciated that the application, typically external application, of hypochlorous acid in as pure and stable a form as possible would be advantageous in the medical industry, particularly insofar as wound treatment, and specifically eye treatment in the context of the present invention, is concerned. Regrettably, at least up until now, it has not been possible for this desired advantage to be fully exploited. The present invention has now made such exploitation possible and has enabled advantageous exploitation of the beneficial effects of ultrapure stabilised hypochlorous acid and is illustrated in ophthamic and wound care conditions.

Hypochlorous acid treatments have not previously been considered for treatment of eye and skin conditions due to poor tolerability for patients. As this invention relates to the use of a particular pure form of ultrapure stabilised hypochlorous acid, one of its important features is that the hypochlorous acid in the treatment solution is not accompanied by the other free chlorine species, notably chlorine Cl₂ gas and hypochlorite OCMons. Chlorine gas and hypochlorite have both been associated with eye irritation, allergy and hypersensitivity reactions. These side effects have been found not to be associated with the treatment preparation and/or treatment preparation solution of the present invention. Not a single case of side effects was noted in clinical cases which were treated with the optimised clinical dose, as described. When a significantly more concentrated formulation of ultrapure stabilised hydrochlorous acid was used in the same clinical population the agent caused irritation and redness which dramatically reduced patient complience and thus observed treatment effect due to the masking effects of eye irritation. A less concentrated sample of ultrapure stabilised hydrochlorous acid was ineffective at clearing symptoms in patients experiencing ocular infections. Noteably when patients from both cohorts were switched to the clinically optimsed dose of ultrapure stabilised hypochlorous acid, all patients experienced a significant treatment effect by 7 days post initiation of treatment with the clinicaly optimised dose, (see FIGURE 5)

Skin and/or flesh wounds

Scar reduction and prevention of keloid as indications for treatment with hypochlorous acid needs special mention. The difference between reparative (normal) healing and regenerative healing of a skin wound in the presence of hypochlorous acid is mentioned below. I n the case of reparative healing, there is a marked inflammatory response with excessive scar tissue being formed. I n the presence of hypochlorous acid, this inflammatory response has been found to be absent and it has been noticed that there is significantly less scar formation, as is also the case with corneal injuries mentioned a bove. It is postulated that the lack of inflammatory response is directly responsible for the control of scar tissue formation. Normal scars, hypertrophic sca rs a nd keloid (a condition where abnormal and symptomatic (itchy, painful) scar tissue grow beyond the confines of the original scar also respond very well to hypochlorous acid treatment. It should be noted that scar tissue per se does, however, not respond well to hypochlorous acid. It is the prevention of scar tissue formation that is indicated. It is therefore ideal that hypochlorous acid treatment of wounds that are potentially prone to keloid formation be treated as soon as it is possible to have access to the wound (after dressings are removed).

Hypochlorous acid is beneficial to wounds for various important reasons. It has been noted that pure hypochlorous acid has an unsurpassed safety profile when it comes to humans (References 7 and 8). For infected wounds to be able to heal, it is of paramount importance that any bacterial contamination be brought under control. On the basis of the literature available it seems very likely that the 'antiseptic' activity displayed by hypochlorous acid is due to a chemico-physical modification of the microenvironment surrounding the area of application (Reference 4). In case of wounds, the control of infection is of extreme importance to improve the healing rate (Reference 5).

Skin conditions

Acne is caused by blockage of oil glands, followed by infection of the accumulated gland contents with the bacterium Propionibacterium acnes. The condition may become worse due to the presence of the male hormone testosterone, which thickens sebum production by the oil glands. Hypochlorous acid benefits acne through various pathways ( Reference 1):

• Hypochlorous acid is very effective against Propionibacterium acnes.

• Hypochlorous acid acts beneficially in reducing the inflammatory lesions (pustules) associated with acne

• The inflammatory lesions are reduced (with concomitant reduction in redness, pain and scar formation) and assistance is rendered in healing the acne lesions.

Regarding pigmentation disorders (which may include post inflammatory hyper pigmentation (PIH): An important function of the skin is to protect the mammalian body from environmental conditions. This protection includes inter alia, but not limited to, physical and chemical irritants. A significant physical irritant is ultra violet light irradiation from exposure to the sun and tanning beds. Chemical irritants include soap, considering that its pH differs vastly from that of normal skin, and different cosmetic ingredients e.g. paraben preservatives, perfume and alcohol derivatives. Sunscreen having very high sun protection factors can also be irritating to the skin due to the chemical irritation from the active ingredients. Whatever the reason for skin irritation, the skin will try to protect the body from the adverse effect of the substance that causes the irritation. Reaction by the skin in this regard may result in discoloration of the skin, with some areas like the cheeks and forehead being susceptible to discolor darker than the rest of the facial skin. This is commonly referred to as melasma. Quite often the surface cells (epidermis) of the skin also become thicker and this gives the skin a rough feel.

Underneath the surface of the skin is a protein layer which is called the Grenz zone. It is in this zone that skin hydration is present. When this layer gets damaged, the skin loses hydration which results in the skin feeling dry.

Hypochlorous acid has different positive benefits to the skin. As an immune modulation substance, its positive effect on the removal of abnormal pigmentation marks has been observed. When the skin of the face is treated with hypochlorous acid over a period of 12 to 16 weeks, there is not only a significant reduction in pigmentation, but also an increase in the visible and perceived hydration levels of the skin. At the same time, the skin feels smoother. The smoother feeling on the skin's surface might be due to the better hydration as well as the hypochlorous acid that causes a shedding of abnormally aggregated surface skin cells.

As a post laser skin-resurfacing or skin peeling treatment, hypochlorous acid applications could play an important role in ensuring a faster healing of the treated skin, reduction in redness and pain in the healing skin and prevention of infection of the treated skin. By preventing the inflammation that usually results from such a skin treatment, hypochlorous acid can play an important part in preventing postinflammatory hyperpigmentation. Treatment of grey hair

Hair color has been associated with reactive oxygen species (Reference 2). Hydrogen peroxide (H2O2) in particular has been shown to be responsible for human gray/white scalp hair. Hair shafts and hair follicles accumulate hydrogen peroxide (H₂0₂) in millimolar concentrations. This is evidenced by data and supports a conclusion that H₂0₂-induced oxidative damage in the entire human hair follicle, inclusive of the hair shaft, is a key element in senile hair graying, which does not exclusively affect follicle melanocytes (the cells responsible for producing the color pigment of hair). Without wishing to be bound by theory, the applicant expects that reversing the build-up of hydrogen peroxide in the hair follicle and hair shaft can be prevented through the regular application of ultrapure stabilised hypochlorous acid as a direct application onto the hair and scalp. Hypochlorous acid immediately reacts with H2O2 according to reaction equation 6:

HOCI+ H202 = H2O + HCI + O2

(Eq. 6)

The elimination of peroxide in the hair follicles and shaft could therefore have an effect on the reversal of grey hair.

Also in the context of grey hair reversal, the present invention is therefore expected to find application.

Dental applications

Dental applications have been examined in the literature, albeit with highly acidic hypochlorous acid water. See in this regard Reference 8. The findings were strongly supportive that irrigation with electrochemically-activated solutions provides efficient cleaning of root canal walls and may be an alternative to sodium hypochlorite (NaOCI) in conventional root canal treatment.

It may be possible to replace dental water lines with ultrapure stabilised hypochlorous acid, as it is not toxic. In this manner, it would become possible to eradicate bacteria from the dental water line, which routinely becomes colonized with bacteria through the municipal water system and through retrograde migration from the mouth of patients. Hypochlorous acid will not only prevent infections like root canal abscess, but also remove biofilm from inside the water lines. Also in the dental context, the present invention is therefore expected to find application. In our experience, a significant improvement was obtained after treating a severe case of periodontal disease for 3 months. After a diagnosis of long standing chronic periodontitis marked by loose teeth, bad breath and bleeding gums, the applicant has treated the condition with mouth rinses twice daily with 100 mg/litre of ultrapure stabilised hypochlorous acid. The condition improved significantly as measured in the teeth being more firm, there was no more bleeding in the gums and the halitosis (bad breath) had disappeared. The patient no longer needed teeth extractions to control his disease.

Control of biofilm

Bacterial colonization of surfaces in a water environment is a normal process in nature as nutrients are available at the solid - liquid interface. The resulting colonies of microorganisms form micro-colonies, which develop into biofilms. Such biofilms are often present on the surface of the eye and prevent access of topical antibiotics from penetrating and exposing the ocular infection to the topically applied antibiotics. The ability of hypochlorous acid to destroy biofilms will dramatically aid the therapeutic ability of ultrapure stabilised hypochlorous acid to be efficacious in treating ocular and indeed wound infection. Additionally, inadaquate care of re-use contact lenses leads to infection and the presence of biofilms on lenses which result in subsequent ocular infection, as such lenses are often stored in an anti-microbial fluid which digests biofilms and have a short shelflife once opened and are often stored refrigerated. Ultrapure stabilised hypochlorous acid could find application as a contact lens storage fluid which required no preservatives, are self-steralising and do not require refrigeration.

Bacterial biofilms have negative consequences in the health industry. Biofilm harbours microorganisms, making it difficult to control the biological burden of infected tissues, including wounds or infection of the eye and other wounds like chronic lower leg wounds or infected open wounds. A number of approaches are currently followed to prevent and/or to remove biofilms:

(i) Chemically treating biofilm with bactericidal compounds other than hypochlorous acid to kill the bacteria. Different bacteria react differently to bactericides, either due to differing cell wall properties, or due to other mechanisms of resistance, either inherent or inducible. There are limits on the application of this method in mammals, since chemicals that destroy biofilm also have negative impact on the vitality of living tissue.

(ii) Dispersing the biofilm by means of dispersants.

(iii) Physical removal of biofilms by a variety of procedures, including scraping the wound or debridement through other methods. These methods also negatively impact on the ability of the body to heal wounds.

(iv) Weakening the biofilm structure by using enzymes or chelants. An enzyme based on paw-paw has been used in humans to remove biofilm, with limited success.

The use of hypochlorous acid has been found, not only effectively to eliminate biofilm, but to do so rapidly and without any negative effect on the living tissue in the wound (Reference 6). The inventor's experience in more than 100 wounds to which the treatment preparation of the present invention was applied is that biofilm is controlled after even a single application of the treatment preparation, which is in contrast to that which is observed with the other treatment methods and when impure hypochlorous acid is used due to tolerability.

Pure and uncontaminated hypochlorous acid has the ability rapidly to control the biological burden of a wound. The rapid control of infection is not only due to its excellent anti bacterial, anti fungal and anti viral properties, but also because hypochlorous acid destroys biofilm (References 7, 8, and 11). Biofilm not only harbours disease forming microorganisms but its presence acts as a barrier to penetration of any disinfectant wound application. The removal of biofilm therefore greatly assists in the treatment of infected wounds. Until now, there have been no safe methods, other than the use of available non-stable high pH forms of hypochlorous acid (sodium hypochlorite) and low pH forms (anolyte), available to treat biofilm in wounds.

Using ultrapure hypochlorous acid in wounds does, however, have significant advantages that are exploitable safely and effectively by the present invention.

Amongst these advantages are the following:

1. Pure hypochlorous acid is one of, if not the, most effective agent against infective microorganisms in wounds. In addition, it is one of, if not the only safe and non toxic wound disinfectant known. All other wound disinfectants have some degree of toxicity on the cells of an open wound.

2. It destroys biofilm.

3. Its immune modulation effect rapidly reduces pain, swelling and redness in the wound.

4. It has a regenerative effect on wounds, which differs from the usual reparative wound healing which has been known up to now.

In removing biofilm with the treatment preparation of the present invention, a gauze swab is wetted with the treatment preparation having been heated to body temperature (36.7 - 37.6 C). The wound is then covered with the wet soaked swab (or swabs, depending on the size of the wound), which is (are) left on the wound for at least 10 minutes, but up to 15 minutes. During this time the swab is constantly wetted with further warmed treatment preparation, so that the wound stays wet and is not allowed to dry out. After the application of the hypochlorous acid wet swab, the wound is covered with a sponge that was saturated with the treatment preparation and then squeeze dried. This procedure is preferably repeated every two days.

HYPOCHLOROUS ACID Hypochlorous acid (chemical symbol HOCI CAS Number 770-92-3) is a well-known chemical substance having known efficacy as a disinfectant. Its efficacy in killing microorganisms is often quantified as being in the order of 100 times greater than the efficacy of its salt, sodium hypochlorite, in this regard (Reference 11). What is also significant in relation to the usefulness of ultrapure hypochlorous acid, particularly in the medical field, is that in a mammalian body, hypochlorous acid occurs inside white blood cells and assists in controlling infection and enabling healing in the body. In the context of the eye, the normal progress of healing of an injured cornea is that small blood vessels grow into the injured part of the cornea, thereby facilitating the transport of white blood cells (containing hypochlorous acid), into that area. Inflammation (redness, swelling and pain) is a normal consequence of the process. The ingrowth of blood vessels is responsible for the development of a white or opaque area in the cornea, called a corneal scar. This impairs vision as the normal transparency of the cornea is now reduced. This method of healing is often referred to as reparative healing (Reference 3).

External application of ultrapure hypochlorous acid causes a different scenario of healing to take place. In essence, studies have found that the healing process thus stimulated is faster with a marked reduction in inflammation and with any concomitant infection being quickly controlled. The use of ultrapure hypochlorous acid as a germicide is not known from the prior art, but previous demostrations of cruder versions of hypochlorous acid containing chlorine gas and hypochlorite ions have been available. Hypochlorous acid physically destructs cell walls of disease-forming microorganisms. Hypochlorous acid kills microorganisms through a physical destruction of their bacterial walls. The bacterial cell membrane provides the osmotic barrier for the cell and facilitates the active transport of nutrients into that cell. Hypochlorous acid causes alternations in the electrical potential across the membrane which is caused by the action of electron donor or electron acceptor factors are associated with the oxidant properties of the hypochlorous acid. The result is rupture of the membranes and outflow of the bacterial cell contents. Even if instantaneous death of the cell does not occur, all enzymatic functions in the membrane are affected and this will also result in loss of cell viability and subsequent death of the microorganism

This differs from the resistance that develops when antibiotics are used. Antibiotics interfere with the metabolism of microorganisms, thereby giving them the opportunity to adapt and circumvent their effect through evolutionary mechanisms of their metabolic processes. This cannot happen with hypochlorous acid, which acts directly on the cell walls of pathogenic organisms.

Tests in relation to a large number of different disease-forming microorganisms have revealed that hypochlorous acid is very effective against all of them. Of important significance is its effect against viral infections of the eye as well as against a myriad of disease-forming microorganisms (including hospital super bugs) in the skin or open wounds. Alternative treatments against viral affliction are very expensive by comparison and usually not available in rural areas. Our novel formulation of ultrapure hypochlorous acid at 50mg/ml concentration, when tested South African Bureau of Standards (SABS) using a contact time of 5 minutes showed a 99.9% kill of P.aruginosa, E. coli and S. aureus.

Additionally, many studies have proven that, as a disinfectant, hypochlorous acid is one of the most powerful killers, if not the most powerful, of disease-forming microorganisms. It kills these microorganisms by destroying their DNA and cell walls, making it impossible for the microorganisms to develop a defence against the hypochlorous acid. Hypochlorous acid can be described as the innate molecule of our immunity. It is unlikely to expect allergy, hypersensitivity or toxic reactions against its presence when applied as an external application. This has been studied and confirmed through many studies. As an external application it is therefore safe and no side effects have been described resulting from its use, provided that certain conditions are met, particularly related to avoiding dissociation of the hypochlorous acid into chlorine, hypochlorite ion and other potentially harmful forms. Hypochlorous acid also has a GRAS (Generally Recognized as Safe) certification from the FDA (FDA 21 Code of Federal Regulation Section 178.1010, Issue number 00-03-13)

The invention has significant advantages over existing hypochlorous acid-based treatment preparations and related methods. In particular it is demonstrated that cruder forms of commercial hypochlorous acid such as Anolyte have undesirable higher levels free active chlorine species such as chlorine gas and hypochlorite ion and are not tolerated when applied to human eye at lower concentrations than are possible with ultrapure stabilised hypochlorous acid prepared (see FIGURE 5 for a comparison of Anolyte vs Ultrapure stabilised hypochlorous acid in the treatment of bacterial conjunctivitis).

Alpesh Desai et al. Efficacy and Tolerability of Electrolyzed Oxidized Water in treating Mild to Moderate Acne, Cosmetic Dermatology Journal, Vol 17 No. 2 February 2004

J. M. Wood et al, Senile hair graying: oxidative stress affects

human hair color by blunting methionine sulfoxide repair, Department of Biomedical Sciences, Clinical and Experimental Dermatology, and Institute for Pigmentary Disorders, University of Bradford, Bradford, UK; Institute of

Molecular Biophysics, University of Mainz, Mainz, Germany; ^Department of Dermatology, University of Lu beck, Lu beck, Germany; and University of Manchester, Manchester, UK

Diegelmann R.F. Wound healing: an overview of acute, fibrotic and delayed healing, Front Biosci. 2004 Jan l;9:283-9.

Scott JM et al., 1982, Todar K, 2008

McLaughlan J et al., 1978, Mertz PM & Ovington LG, 1993, Bowler PG et al., 2001

Eugene Cloete. Electrochemically activated water as a non-polluting biofilm control technology, Department of Microbiology and Plant Pathology University of Pretoria, Pretoria, South Africa

Bowler PG et al., Wound Microbiology and Associated Approaches to Wound Management2001

1 2

A.M.Solovyeva & P.M.H.Dummer Cleaning effectiveness of root canal irrigation with electrochemically activated anolyte and catholyte solutions: a pilot study

¹ Faculty of Stomatology, St. Petersburg I. P. Pavlov's State Medical University, St. Petersburg, Russia CIS; ² Department of Adult Dental Health, University of Wales College of Medicine, Cardiff, UK H.D. Dakin. On The Use Of Certain Antiseptic Substances In The Treatment of Infected Wounds. British Med Journal August 25 1915

M Ortiz-Repiso. Structure and spectra of HOCI (H20)(n) clusters, n=l-4: A theoretical calculation

http://www.iem. cfmacxsic.es/depa rtamentos/fismol/Abstract/Structure%20 and%2Qspectra%2Qof%2QHQCLpdf Fact Sheet: Disinfection Using Chlorine Bleach December, 2011 / Oragon State University Biological Safety / Environmental Health & Safety / 541-737- 4557)

Kirk-Othmer Encyclopedia of Chemical Technology, 2^nd Edition, Vol.4, pg. 911

Chong-Hou Sam, Hsein-Kun Lu. The role of hypochlorous acid as one of the reactive oxygen species in Periodontal disease. J Dent Sci 2009; 4(2); 45 - 54

Claims

1. A stable solution of hypochlorous acid in water which is low in chlorine gas and hypochlorite ions.

2. The solution of claim 1, wherein the solution comprises less than 30%, more preferably less than 25%, more preferably less than 20% chlorine gas.

3. The solution of claim 1 or claim 2, wherein the solution has a pH of between 3.5 and 7, more preferably between 3.5 and 6.3, more preferably between 4 and 6, even more preferably between 4.5 and 5.4.

4. The solution of claim 3, wherein the solution is prepared at between 3.5 and 7, more preferably between 3.5 and 6.3, more preferably between 4 and 6, even more preferably between 4.5 and 5.4.

5. The solution of any preceding claim, wherein the solution comprises hypochlorous acid at a concentration of between about 30 milligrams per litre and about 120 milligrams per litre, more preferably between about 33 to 109 milligrams per litre, more preferably between about 73 to 105 milligrams per litre, e.g. about 80 milligrams per litre or 100 milligrams per litre.

6. The solution of claim 5, wherein the hypochlorous acid is at a concentration of about 80 milligrams per litre and the composition has a pH of about 5.4.

7. The solution of claim 5, wherein the hypochlorous acid is at a concentration of about 100 milligrams per litre and the composition has a pH of about 4.5.

8. A method for preparing a hypochlorous acid solution according to the invention, comprising the step of electrolysis of hydrochloric acid and water in an electrolysis chamber.

9. The method of claim 8, wherein the electrolysis chamber comprises titanium and iridium dioxide electrodes.

10. A solution produced by the method of claim 8 or claim 9

11. A pharmaceutical composition or dressing or disinfecting or cleaning composition, for example for contact lens and for dental lines, comprising a solution according to any of claims 1 to 7 or 10.

12. A solution according to any of claims 1 to 7 or 10, for use in therapy.

13. A solution according to any one of claims 1 to 7 or 10, for use in the treatment of an ocular condition, such as an ocular condition selected from an ocular injury, an ocular infection, a condition of increased pressure inside the eye, degenerative conditions of the retina and optic nerve, a cataract, such as bacterial conjunctivitis, trachoma, viral conjunctivitis, fungal infection of the eye, meibomianitis, allergic conjunctivitis, corneal ulcer, corneal chemical burn, allergic conjunctivitis, superior limbic keratoconjunctivitis (episcleritis), corneal viral infection, ocular herpes viral infection, corneal scarring, scleral ptergium, blepheritis, scleral laceration, corneal angiogenesis, cateract reversal, neovascular macular degeneration, corneal acute viral endothelitis; a dental condition, such as a dental condition selected from periodontitis, loose teeth, bad breath, bleeding gums; a skin condition such as a skin condition selected from acne, rosacea, impetigo, cellulitis, fungal infections of the skin for example tinea pedis, pityriasis versicolor, tinea versicolor and candidiasis, viral infections of the skin for example herpes fever blisters and zoster, nappy rash, psoriasis, eczema and pigmentation disorders of the skin, including post inflammatory hyper pigmentation (PIH), or to improve skin hydration; wounds, including skin and flesh wounds, such as burns, pressure sores, chronic wounds, diabetic ulcers, elective surgery wounds for example abdominal surgery wounds, thoracotomy wounds, gynecological wounds, plastic surgery wounds, ear nose and throat surgery wounds, orthopedic surgery wounds and stoma therapy wounds, wounds and infection of those wounds following a bite injury, especially from a dog or human; scars and scarring, including the treatment of scar tissue such as keloid scarring, or prevention or reduction of scar formation; or grey hair; or for use as a disinfecting agent prior to providing an intravitreal injection of a ocular therapeutic or by intracameral, intrascleral, intra-corneal, subconjunctival sub-tenon injection of the same.

14. A method of treating a condition selected from an ocular condition, such as an ocular condition selected from an ocular injury, an ocular infection, a condition of increased pressure inside the eye, degenerative conditions of the retina and optic nerve, a cataract, such as bacterial conjunctivitis, trachoma, viral conjunctivitis, viral keratitis, fungal infection of the eye, meibomianitis, allergic conjunctivitis, corneal ulcer, corneal chemical burn, allergic conjunctivitis, superior limbic keratoconjunctivitis (episcleritis), corneal viral infection, ocular herpes viral infection, corneal scarring, scleral ptergium, blepheritis, scleral laceration, corneal angiogenesis, cateract reversal, neovascular macular degeneration; a dental condition, such as a dental condition selected from periodontitis, loose teeth, bad breath, bleeding gums; a skin condition such as a skin condition selected from acne, rosacea, impetigo, cellulitis, fungal infections of the skin for example tinea pedis, pityriasis versicolor, tinea versicolor and candidiasis, viral infections of the skin for example herpes fever blisters and zoster, nappy rash, psoriasis, eczema and pigmentation disorders of the skin, including post inflammatory hyper pigmentation (PIH), or to improve skin hydration; wounds, including skin and flesh wounds, such as burns, pressure sores, chronic wounds, diabetic ulcers, elective surgery wounds for example abdominal surgery wounds, thoracotomy wounds, gynecological wounds, plastic surgery wounds, ear nose and throat surgery wounds, orthopedic surgery wounds and stoma therapy wounds, wounds and infection of those wounds following a bite injury, especially from a dog or human; scars and scarring, including the treatment of scar tissue such as keloid scarring, or prevention or reduction of scar formation; or grey hair; or of disinfecting an area prior to providing an intravitreal injection of a ocular therapeutic or by intracameral, intrascleral, intra-corneal, subconjunctival sub-tenon injection of the same, comprising administering an effective amount of a solution according to any one of claims 1 to 7, or 10 or a composition according to claim 11 to a subject in need thereof.

15. A solution according to claim 6 for use in the treatment of skin conditions, or a solution according to claim 7 for use in the treatment of ocular conditions.

16. An electrolysis device for production of the solution of any of claims 1 to 7 or 10, the device comprising an electrolysis chamber, and an inlet capable of providing a controlled flow rate of reactant into the chamber, wherein the flow rate may be controlled such that the flow rate is less than 150l/h.

17. An electrolysis device according to claim 16, further comprising a electrical current sensor to monitor the electrical current across the electrodes in the chamber

18. An electrolysis device of claim 16 or 17, further comprising a means for altering the flow rate of the reactant into the chamber, in response to a change in electrical current in the chamber, so as to control the concentration of the hypochlorous acid produced.