COMPOSITIONS FOR REMOVING NECROTIC OR INFECTED TISSUES FROM BODY SURFACE LESIONS

Abstract

A composition, usable for removing a biofilm and necrotic or infected tissues from a skin lesion, comprises ethanesulfonic acid or 1-propanesulfonic acid and a proton acceptor. The proton acceptor is selected from the group consisting of: dimethyl sulfoxide, silicon dioxide, tetraethoxysilane, and mixtures thereof. The aforesaid composition can be prepared in the form of a gel.

Claims

1.-9. (canceled)

10. A method for removing biofilm and necrotic or infected tissues from a skin lesion, the method comprising administering to the skin lesion a composition comprising ethanesulfonic acid or 1-propanesulfonic acid.

11. The method of claim 10, wherein the ethanesulfonic acid is ethanesulfonic acid 97% and the 1-propanesulfonic acid is 1-propanesulfonic acid 98%.

12. The method of claim 10, wherein the composition further comprises a proton acceptor.

13. The method of claim 12, wherein said proton acceptor is selected from the group consisting of: dimethyl sulfoxide, silicon dioxide, tetraethoxysilane, and mixtures thereof.

14. The method of claim 10, wherein the composition is prepared in the form of a gel.

15. The method of claim 13, wherein the composition has the following formulation: TABLE-US-00004 Ethanesulfonic acid 70-90% by weight Dimethyl sulfoxide  5-20% by weight Silicon dioxide   1-8% by weight Tetraethoxysilane 0.05-2% by weight.

16. The method of claim 13, wherein the composition has the following formulation: 1-propanesulfonic acid 70-90% by weight TABLE-US-00005 Dimethyl sulfoxide  5-20% by weight Silicon dioxide   1-8% by weight Tetraethoxysilane 0.05-2% by weight.

17. The method of claim 10, wherein the method comprises removing the composition from the skin lesion after a contact time of a few tens of seconds has elapsed.

18. The method of claim 10, wherein the skin lesion is a chronic cutaneous ulcer.

19. A composition comprising ethanesulfonic acid or 1-propanesulfonic acid suitable for removing biofilm and necrotic or infected tissues from a skin lesion, wherein the composition further comprises a proton acceptor.

20. The composition according to claim 19, wherein said proton acceptor is selected from the group consisting of: dimethyl sulfoxide, silicon dioxide, tetraethoxysilane, and mixtures thereof.

21. The composition according to claim 19, wherein the composition is prepared in the form of a gel.

22. The composition according to claim 19, wherein the composition has the following formulation: TABLE-US-00006 Ethanesulfonic acid 70-90% by weight  Dimethyl sulfoxide  5-20% by weight Silicon dioxide   1-8% by weight Tetraethoxysilane 0.05-2% by weight.

23. The composition according to claim 19, wherein the composition has the following formulation: TABLE-US-00007 1-propanesulfonic acid 70-90% by weight  Dimethyl sulfoxide  5-20% by weight Silicon dioxide   1-8% by weight Tetraethoxysilane 0.05-2% by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention can be better understood and implemented with reference to the enclosed drawings that illustrate an embodiment thereof by way of non-limiting example in which:

[0021] FIG. 1 is a photograph of a Petri dish showing a microbial growth inhibition halo around the depositing zone of a sample of a composition (containing ethane sulfonic acid) according to the invention;

[0022] FIG. 2 is a photograph of a Petri dish showing a microbial growth inhibition halo around the depositing zone of a sample of a composition (containing 1-propanesulfonic acid) according to the invention;

[0023] FIGS. 3A to 3D are photographs showing a wound that was treated and healed after a single application of the composition (containing ethane sulfonic acid) according to the invention;

[0024] FIGS. 4A to 4D are photographs showing a wound that was treated and healed after a single application of the composition (containing 1-propanesulfonic acid) according to the invention;

DETAILED DESCRIPTION OF THE INVENTION

[0025] The composition according to the invention comprises ethanesulfonic acid or 1-propanesulfonic acid as active principles and is formulated as a gel, which can be easily applied on chronic cutaneous ulcers.

[0026] A surprisingly unexpected property of the composition according to the invention is that the latter is able to act in a few tens of seconds on the biofilm and on the necrotic or infected tissues, causing a rapid desiccation thereof and enabling the removal thereof (through washing or sterile gauze) only a few seconds after the application and thus avoiding complicated, painful and costly surgical procedures (debridement).

[0027] The action of the composition is due to the release of hydrogen ions (H.sup.+) or protons that, possessing a great hydration enthalpy (−1130 KJ/mole), cause the dehydration of the microbial species that make up the biofilm or proliferate in the infected tissues.

[0028] This action mechanism is achieved regardless of the microbial species present and makes the composition according to the invention active against any microbial species, whether bacterial, fungal or viral.

[0029] The Inventors have carried out researches to identify the most suitable source of protons, namely a source that is such as to enable an effective release of the protons in contact with the skin, with resulting denaturation of the microbial proteins present therein, without however causing damages to the healthy tissue surrounding the lesions. This requires the preparation of appropriate formulations where the release of the protons is optimized, for example by varying the degree of viscosity of the formulations on the basis of the type of lesion for which the use of the composition according to the invention is intended.

[0030] The potentially usable sources of protons essentially consist of strong acids (HA), which have to be used in concentrated form, namely in the presence of the least possible amount of water.

[0031] This is required because the dissociation of the strong acid into H.sup.+ protons and A.sup.− anions has to occur in contact with the microbial species, subtracting molecules of water from the latter, which molecules will form the hydration sphere of the H+ protons with release of thermal energy (−1130 KJ/mole).

[0032] The dosage of the H+ protons released by the acid species in concentrated form is problematic as it is not possible to dilute with water, which nevertheless represents the best solvent for solubilizing ethanesulfonic acid or 1-propanesulfonic acid.

[0033] As it is known, the acid dissociation constant (K.sub.a) relating to the reaction HA.fwdarw.H.sup.++A.sup.− is defined by the following relation:

K.sub.a=[H.sup.+][A.sup.−]/[HA]

in which the concentrations in moles/litre of the different species are indicated between square brackets. The negative decimal logarithm of the acid dissociation constant is defined as pK.sub.a (pK.sub.a=−log K.sub.a).

[0034] In the following Table 1, the pK.sub.a values are shown (at a temperature of 25° C.) of the main strong acids, which dissociate completely, or almost completely, in an aqueous environment.

[0035] From Table 1 it can be inferred that the trifluoromethanesulfonic acid is the strongest acid (namely, the acid having the highest pK.sub.a value), whereas the trifluoroacetic acid is the weakest acid:

TABLE-US-00001 TABLE 1 Acid Chemical formula pK.sub.a Trifluoromethanesulfonic CF.sub.3SO.sub.3H −13 Hydroiodic HI −10 Perchloric HClO4 −10 Hydrobromic HBr −9 Hydrochloric HCl −8 Sulphuric H.sub.2SO.sub.4 −3 Nitric HNO.sub.3 −1.4 Ethanesulfonic acid CH.sub.3CH.sub.2SO.sub.3H −1.3 1-Propanesulfonic acid CH.sub.3CH.sub.2CH.sub.2SO.sub.3H −0.86 Trifluoroacetic CF3COOH −0.25

[0036] Considering the volatility of the hydroiodic, hydrobromic, hydrochloric and trifluoroacetic acids, as well as the oxidizing action of the perchloric and nitric acids, which can cause undesired effects on the skin, the Inventors focused the attention on the sulfonic acid derivatives with ethyl and propyl substituents, which have much lower dissociation constants with respect to sulphuric acid.

[0037] The Inventors further provided for the use of ethanesulfonic acid or 1-propanesulfonic acid in combination with suitable proton acceptors (or protonic acceptors), which enable the acidity of the composition according to the invention to be adjusted, and more exactly to be reduced. The protonic concentration has to be reduced because the protons, if they are released in an excessive quantity, may cause the dehydration of the epithelial cells with consequent oedema, erythema, desquamation and tissue necrosis with formation of ulcers. By reducing the concentration of the protons released by the ethanesulfonic acid or 1-propanesulfonic acid, these acids can be effectively used in the treatment of lesions (chronic cutaneous ulcers) in which the biofilm is present for producing a desired dehydrating effect against the contaminating microbial species without however damaging the surrounding healthy tissues.

[0038] In one embodiment of the composition, according to the invention, the proton acceptor comprises anhydrous dimethyl sulfoxide (DMSO), which is added to a concentrated solution of ethanesulfonic acid. The DMSO enables the acidity to be reduced of the composition according to the invention by protonation of the oxygen atom thereof.

[0039] In another embodiment of the composition according to the invention, the proton acceptor comprises silicon dioxide particles with diameters in the range 200-400 nm. This enables the acidity of the composition according to the invention to be reduced through the protonation of the oxygen present at the surface of the silica particles controlling at the same time the viscosity of the resulting gel.

[0040] In a further embodiment of the composition according to the invention the rheology of the gel containing the sulfonic acids can be controlled though addition of tetraethyl orthosilicate, able of binding the silicon dioxide particles.

[0041] The aforesaid different embodiments of the composition according to the invention enable an equilibrium to be established between the ethanesulfonic acid or 1-propanesulfonic acid (indicated by HA) and proton acceptors (indicated generally by B). This equilibrium is disclosed by the reaction HA+B.Math.A−+HB and has as a result a reduction of the concentration of the sulfonic acid without introduction of dilution water, maintaining the antimicrobial effect of the composition according to the invention and the efficacy of the latter in removing biofilm and tissues rapidly and painlessly.

[0042] The chemical components that are more suitable for preparing the various embodiments of the composition according to the invention are summarized below. Of these, ethanesulfonic acid and 1-propanesulfonic acid are the active principles, whilst all the other listed components are suitable proton acceptors:

[0043] Ethanesulfonic acid 97%; CAS N. 594-45-6

##STR00001##

[0044] 1-Propanesulfonic acid 98%; CAS N. 5284-66-2

##STR00002##

[0045] Dimethyl sulfoxide or DMSO or (CH.sub.3).sub.2SO, CAS N. 67-68-5

##STR00003##

[0046] Silicon dioxide or SiO.sub.2; CAS 112945-52-5

[0047] Tetraethyl orthosilicate or tetraethoxysilane or TEOS or Si(OC.sub.2H.sub.5).sub.4; CAS N. 78-10-4

##STR00004##

[0048] In the following Tables 2 and 3, possible qualitative and quantitative formulations of the composition according to the invention are disclosed in greater detail by way of non-limiting examples. The expression “possible qualitative and quantitative compositions” should be understood in the sense that a person skilled in the art can easily and suitably modify each of the formulations of the composition according to the invention (for example, through the addition of pharmacologically acceptable excipients) on the basis of the physical form of administration (solution, cream or gel), provided that the composition always contains ethanesulfonic (first formulation) or 1-propanesulfonic acid (second formulation) as an active principle and at least one suitable proton acceptor.

TABLE-US-00002 TABLE 2 First formulation (formulation containing ethanesulfonic acid) Component Percentage by weight Ethanesulfonic acid 70-90% Dimethyl sulfoxide  5-20% SiO.sub.2   1-8% TEOS 0.05-2%

TABLE-US-00003 TABLE 3 Second formulation (formulation containing 1-propanesulfonic acid) Component Percentage by weight 1-Propanesulfonic acid 70-90% Dimethyl sulfoxide  5-20% SiO.sub.2   1-8% TEOS 0.05-2% 

[0049] The procedures for preparing the formulations referred to in the previous Tables 2 and 3 are not disclosed in detail below, because the chemical components of the formulations can be added to the sulfonic acids—namely ethanesulfonic acid and 1-propanesulfonic acid—according to a variable order and nevertheless without altering the properties of the final solution. In fact, the different chemical components are solubilized without reactions intervening that are able to interfere with the phenomenon of the protonation of the proton acceptors.

[0050] By way of non-limiting example of the invention, the following Examples are disclosed: a test of in vitro antimicrobial activity of the composition according to the invention (Example 1); a procedure for treating skin lesions by using the composition according to the invention (Example 2); treatment of a wound by using the first formulation (containing ethanesulfonic acid) of the composition according to the invention (Example 3); treatment of a wound by using the second formulation (containing 1-propanesulfonic acid) of the composition according to the invention (Example 4).

Example 1—Test of In Vitro Antimicrobial Activity

[0051] The antimicrobial activity of a formulation containing 87% ethanesulfonic acid (first formulation) or a formulation containing 87% 1-propanesulfonic acid (second formulation), both formulations containing 9.8% DMSO, 0.05% Parared, 2.2% SiO2 and 0.95% TEOS, was tested against the following strains of microorganisms (purchased from Diagnostic International Distribution S.p.A.): Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 10536, Enterococcus hirae ATCC 10541, Candida albicans ATCC 10231. Mixtures of the different strains of microorganisms were prepared, having concentrations expressed as colony forming units (CFU) comprised between 1.5×10.sup.12-5.5×10.sup.12 for each species. 100 μl samples of the mixture were inoculated on Petri dishes containing TSA (Tryptone Soya Agar) solid culture medium. The inoculation was carried out according to a known and standardized analytical method, namely by depositing the liquid sample on the surface of the agar by a micropipette and distributing the liquid sample on the surface of the agar by using sterile glass beads. Subsequently, 50 μl aliquots of the two formulations of the composition according to the invention were deposited in a central zone of the agar of each Petri dish. The dishes were then incubated at 37° C. for 24 h.

[0052] FIGS. 1 and 2 show two Petri dishes, in each of which a 50 μl aliquot was deposited respectively of the first and second formulation of the composition according to the invention.

[0053] After the incubation, the dishes were examined in order to evaluate the microbial proliferation (formation of colonies) and the width of the inhibition halo (namely, the width of the portion of medium in which the microbial proliferation had been inhibited) surrounding the zone of agar on which samples of the two formulations had been deposited. As shown in FIGS. 1 and 2, in all the Petri dishes clear zones of microbial growth inhibition were observed, surrounding the depositing zones of the preparations according to the invention. The analytical result obtained indicates that the two formulations of the composition according to the invention are able to inhibit the growth of 10.sup.11 CFU of gram-positive bacteria, gram-negative bacteria and of the fungal species Candida albicans.

Example 2—Treatment of Patients Affected by Chronic Cutaneous Ulcers

[0054] The composition according to the invention (first formulation and second formulation) were tested on over 10 patients each, who were volunteers, by applying a treatment protocol comprising the following steps:

[0055] Removing with a sterile gauze the easily removable necrotic materials that are present on the bottom of the ulcer;

[0056] Drying completely the bottom of the ulcer;

[0057] Only in the case of particularly sensitive patients, for whom a painful response is expected, pre-treating the bottom of the ulcer for a time of about 5 minutes with a pack of ointment containing 5% lidocaine;

[0058] Removing the pack, washing the ulcer to remove the lidocaine ointment and drying;

[0059] Applying the composition according to the invention on the bottom of the ulcer and on the surrounding skin for about 1 cm beyond the edge of the ulcer, by using the finger of a hand covered by sterile single-use glove;

[0060] Letting the composition according to the invention to act for about 20-30 seconds;

[0061] Washing abundantly with sterile physiological solution;

[0062] Drying with sterile gauze;

[0063] Rubbing the bottom of the ulcer with sterile gauze to remove the desiccated material;

[0064] Leaving on the bottom of the ulcer the possible desiccated material that did not detach itself through the effect of rubbing with the gauze;

[0065] Covering the ulcer with a sterile greasy gauze or with another type of suitable medication (according to the choice of the operator);

[0066] Bandaging the zone according to known procedure;

[0067] Performing subsequent checks at 7-day intervals, or at shorter intervals if deemed necessary.

[0068] During each check, the aforesaid protocol provides for proceeding in the following manner:

[0069] Removing bandages and medication;

[0070] Removing progressively, by using normal pliers and scissors and starting from the edges of the lesion, the desiccated material left on the bottom of the ulcer;

[0071] Covering the ulcer with a sterile greasy gauze or with another type of suitable medication (according to the choice of the operator);

[0072] Bandaging the zone according to known procedure.

When the bottom of the ulcer is covered by granulation tissue, upon complete granulation and according to the choice of the operator, it is possible to graft skin and/or skin substitute in the lesion to complete the healing process.

[0073] The treatment protocol disclosed above resulted to be effective in desiccating the bottom of the ulcers in all the treated patients. No complications and/or side effects emerged at the systemic or local level or on the perilesional skin. In all the treated patients the residual desiccated material disappeared progressively at the end of the procedure without the need for an additional intervention and left a granulation tissue on the bottom of the lesion.

Example 3—Wound Treated by a Single Application of the Composition According to the Invention, Containing Ethanesulfonic Acid (First Formulation)

[0074] With reference to FIGS. 3A-3D, a treatment of a mixed arteriosus-venous ulcer of a lower limb is shown. The treated patient did not respond to previous several types of treatment and the ulcer lasted for almost one year. FIG. 3A shows the ulcer before treatment. FIG. 3B shows the ulcer immediately after the application of the composition containing ethanesulfonic acid. The desiccant effect of the product is clearly seen, as the slough in the wound bed was instantaneously transformed in a dried layer. The surrounding skin appeared degreased, but without any inflammatory response. No redness, wheals or bullae can be seen. Moreover, a sharp demarcation between the wound bed and the normal skin became apparent. FIGS. 3C and 3D show respectively the ulcer after 1 and 2 weeks from the initial treatment. It can be noticed that the desiccated material on the wound bed progressively disappeared and the granulation tissue covered the entire wound bed. The disappearance of the desiccated material is due to the rubbing with gauze during follow-up medication. However, an autolytic effect due to reactivation of patient's macrophages, no more inhibited by inflammatory proteins, cannot be ruled out.

Example 4—Wound Treated by a Single Application of the Composition According to the Invention, Containing 1-Propanesulfonic Acid (Second Formulation)

[0075] FIGS. 4A to 4D show the treatment of a post traumatic wound in a patient's leg, with the bottom of the wound bed close to the bone. FIG. 4A shows the skin ulcer before treatment: a yellow area can be seen in the upper right part of the wound bed representing the presence of a biofilm. FIG. 4B shows the skin ulcer immediately after application of the composition containing 1-propanesulfonic acid and rinsing with saline. The desiccant effect is clearly seen without affecting the surrounding normal skin. The ulcer was then simply covered with a fat gauze. As shown in FIG. 4C, full granulation of the wound bed was gradually reached in the subsequent two weeks. Fat gauze was changed weekly. FIG. 4D shows that complete healing by spontaneous reepithelization was reached after 5 weeks.

[0076] Examples 3 and 4 clearly show that the application of the composition according to the invention (containing ethanesulfonic acid or 1-propanesulfonic acid with proton acceptors) produced in all the cases a complete restoration of the tissues in the lesion, promoting the healing thereof. The treatment protocol disclosed above (see Example 2) can be applied to all the patients, thus avoiding complicated, costly and potentially risky surgical procedures. Furthermore, the treatment with the composition according to the invention can reduce the need to use antibiotic therapies, which are substantially costly and associated with the increasingly rising phenomenon of the antibiotic resistance.

[0077] As a person skilled in the art will understand, variations on and/or additions to what has been disclosed above are possible. For example, although the previously disclosed compositions were prepared on laboratory scale, the person skilled in the art is able to provide preparation procedures that are suitable for a production on industrial scale.