GB2459126A

GB2459126A - Antimicrobial agent

Info

Publication number: GB2459126A
Application number: GB0806554A
Authority: GB
Inventors: Peter Wilson
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-04-10
Filing date: 2008-04-10
Publication date: 2009-10-14
Also published as: GB0806554D0

Abstract

Compounds of general formula (1) wherein R1 and R2 and R3 are independently selected from the group comprising CH 2 COOH or (CH 2 ) m N(CH 2 COOH) 2 and m is 1-3; or a salt thereof, for use in the treatment of bacterial or fungal infection particularly for the treatment of drug-resistant bacterial infections such as MRSA, acinetobacter baumannii, vancomycin resistant enterococcus (VRE) or extended spectrum beta-lactamase producers (ESBLs). The compounds may be ethylene diamine tetraacetic acid (EDTA), nitrillotriacetic acid (NTA), or diethylene triamine pentaacetic acid (DTPA) The compound may be used pharmaceutically, as a disinfectant, antiseptic, or for the impregnation of fabric.

Description

Anti-Microbial Agent The present invention relates to an anti-microbial and antibiotic agent for combating bacteria and fungi.

Given good conditions bacteria have a generation time of around 20 minutes. They can adapt relatively easily, since they have an enormous evolutionary advantage.

Known antibiotics therefore, become ineffective quite swiftly. Even when the value of penicillin was first recognised in 1941 there were strains of staphylococci that were io resistant to penicillin, but well over 90% were sensitive. However, it clearly being an advantageous for staphylococci to be resistant to penicillin because so much of it was being used, these bacteria have adapted and the picture today is very much changed from previous years. At present 99% of staphylococci are resistant to penicillin. This pattern of developing resistance to antibiotics has been repeated with more and more antibiotics losing their ability to kill the bacteria and hence the evolution of bacteria such as meticillin-resistant staphylococci aureus (MRSA). These multiply-resistant" bacteria usually originate in hospitals, where antibiotics and antibacterial agents are most intensively used. Such bacteria are dubbed "superbugs" because of their high resistance to many of the known antibiotics and anti-microbial agents. Although MRSA has probably received the greatest amount of press it is not the only hospital "superbug" For example, Acinetobacterbaumannii is frequently found in intensive care units across the globe and is usually sensitive to only one or two antibiotics. This organism is capable of causing life threatening infection in these intensive care patients Also there is the vancomycin resistant enterococcus (VRE), which often arises in renal units, and "ESBLs" (Extended Spectrum Beta-Lactamase producers) which, by virtue of their ability to produce enzymes (beta-lactamases) which destroy the antibacterial agent, are resistant to a large number of antibiotics.

Diethylene triamine penta-acetic acid (DTPA) is well known as a chelating agent due to its high affinity for metal cations. It has the chemical structure: DTPA has been used as a chelating agent to treat internal contamination from radioactive materials such as americium, plutonium, californium, curium and berkelium. It is also used as a soil extractant for available soil micron utrients like Zn, Ag, Fe, Cu and Mn. Furthermore, it is used to chelate gadolinium to form an MRI contrast agent, such as Magnevist. Due to its chelating action, DTPA is also in regular use in the textile industry for removing rust stains from cotton or linen and for preparing the fabric for dyeing.

In addition, DTPA has been used as an anti-microbial preservative in propofol, which is an anaesthetic (see WO 2000/059472).

It has also been used as an Fe(lll) chelating agent to inhibit bacterial growth without is bactericidal action in deodorants (see International Journal of Cosmetic Science, Volume 25, Issue 3, page 127-1 35, June 2003: "Iron sequestration on skin: a new route to improved deodorancy" by S. Landa et a!).

Moreover, DTPA Fe (Ill) has been demonstrated to protect mice and baboons from the lethal effects of an infusion with live LD100 Escherichia co/i by protecting them against free radical overproduction (see J. Clin. Invest., Volume 98, Number 1, July 1996, pages 192-198: "Efficacy of treatment with iron (Ill) complex of diethylenetriamine pentaacetic acid in mice and primates inoculated with live lethal dose 100 Eschirichia co/P1 by Molina et a!..

An object of the present invention is to provide an anti-bacterial and antibiotic agent that is effective against superbugs such as MRSA.

The inventor has demonstrated that DTPA has a clear, unexpected activity in the treatment of otherwise highly resistant bacteria, including MRSA and other multiply resistant organisms, such as acinetobacter and vancomycin resistant enterococci (VRE) infections, as well as a fungicidal activity. This activity could certainly not have been anticipated from the previous known properties and uses of the compound. Related chelating agents have similar activity. Therefore, in a first aspect of the present invention, there is provided a compound of general formula (I): 1 3

R-R (I)

wherein each of R1, R2 and R3 is independently selected from CH2C(O)OH or (CH2)mN(CH2C(O)OH)2 is mislto3; or a salt thereof; for use in the treatment of bacterial infection.

The invention also provides a method for the treatment of bacterial infection, the methOd comprising administering to a patient in need of such treatment an effective amount of a compound of general formula (I).

In addition, there is provided the use of a compound of general formula (I) in the preparation of an agent for the treatment of bacterial infection, In the present invention, the following definitions have been used.

"Antimicrobial agent" refers to an agent which is active against bacteria and/or viruses and br fungi. An antimicrobial agent may be administered to patients as a pharmaceutical or may be used for treating surfaces or materials so as to confer temporary or permanent antibacterial properties on those surfaces or materials.

An "antibacterial agent" refers to an antimicrobial agent which is active against bacteria.

The term "antibiotic" refers to an antibacterial pharmaceutical agent which may be either naturally occurring or synthetic and which may be administered to patients to treat bacterial infection via any suitable route, for example topically, transdermally or by the oral, buccal, sublingual, nasal, rectal routes or parenterally, for example intravenously or intramuscularly, or by any other route.

A disinfectant as used in the present specification refers to a composition which is active against bacteria and/or viruses and /or fungi. In general, a disinfectant will not be brought directly into contact with humans, but will be used as a cleaning agent on hard surfaces, instruments etc is In the present specification the term "antiseptic" refers to a composition which is active against bacteria and/or viruses and /or fungi but which is safe to use as a local application on the skin or on wounds.

In the present specification, drug or antibiotic resistant bacteria are bacteria which are not killed by the drug or antibiotic used to treat them.

Suitable salts of compounds of general formula (I) are, in particular, group I or group II metal salts, for example sodium potassium or calcium salts. Alternatively, the ammonium salts may be used. Other salts may also be used.

The compounds of general formula (I) are useful for the treatment of all bacterial infections, including both gram positive bacteria such as Staphylococcus and Enterococcus species and gram negative bacteria such as Acinetobacter species and Extended Spectrum Beta-Lactamase producers (ESBL5).

Although as mentioned above, compounds of general formula (I), for example DTPA, have been used in medicine, they have not previously been used for the treatment of bacterial infections and therefore have the great advantage that bacteria have not developed resistance to them. Because of this, they are of particular use in the treatment of infection by bacteria which occur in hospitals rather than in the community In particular, the compounds are useful for the treatment of bacteria which are resistant to one or more antibiotic agents. Examples of such bacteria include MRSA, Acinetobacter baumannii., VRE and ESBLs.

Although any compound of general formula (I) may be used in the present invention, compounds which have proved to be suitable for use in the present invention are io those in which at least one of R1, R2 and R3 is CH2C(O)OH.

Specific examples of particularly suitable chelating agents of general formula (I) include: diethylene triamine pentaacetic acid (DTPA), which has the structure: (IOH (OH HO'0 ethylene diamine tetraacetic acid (EDTA), which has the structure: and N,N-bis(carboxymethyl)glycine or Triglycollamic acid (NTA), also known as Trilone A, which has the chemical structure: DTPA has been found to give particularly successful results when used in the present invention.

The compounds of general formula (I) will generally be used in the form of a composition admixed with other agents and therefore, in a further aspect, the present invention provides a composition comprising a compound of general formula (I).

Compositions of the present invention comprise pharmaceutical compositions, io including compositions for hospital and drug-resistant bacteria, disinfectant compositions, antiseptic compositions, and compositions suitable for treating fabrics.

When used as an antibacterial agent as set out above, the compound of general formula (I) may be supplied in the form of a pharmaceutical composition and is therefore there is provided an antibacterial pharmaceutical composition comprising a compound of general formula (I) as an active agent together with a pharmaceutically acceptable excipient or carrier.

The carrier, or, if more than one be present, each of the carriers, must be acceptable in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient.

The formulations include those suitable for oral, rectal, nasal, bronchial (inhaled), topical (including eye drops, buccal and sublingual), vaginal or parenteral (including subcutaneous, intramuscular, intravenous and intradermal) administration and may be prepared by any methods well known in the art of pharmacy.

The route of administration will depend upon the condition to be treated but preferred compositions are formulated for oral, topical, intravenous, intra-muscular or rectal administration. A particularly preferred form of administration for the treatment of MRSA is topical administration in the nasal passages.

The composition may be prepared by bringing into association the above defined active agent with the carrier. In general, the formulations are prepared by uniformly and intimately bringing into association the active agent with liquid carriers or finely divided solid carriers or both, and then if necessary shaping the product. The invention extends to methods for preparing a pharmaceutical composition comprising bringing a novel compound of general formula (I) in conjunction or association with a io pharmaceutically or veterinarily acceptable carrier or vehicle, Formulations for oral administration in the present invention may be presented as: discrete units such as capsules, sachets or tablets each containing a predetermined amount of the active agent; as a powder or granules; as a solution or a suspension of the active agent in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water in oil liquid emulsion; or as a bolus etc. For compositions for oral administration (e.g. tablets and capsules), the term "acceptable carrier" includes vehicles such as common excipients e.g. binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, polyvinylpyrrolidone (Povidone), methylcellulose, ethylcellulose, sodium carboxymethylcellulose, hydroxypropylmethylcellulose, sucrose and starch; fillers and carriers, for example corn starch, gelatin, lactose, sucrose, microcrystalline cellulose, kaolin, mannitol, dicalcium phosphate, sodium chloride and alginic acid; and lubricants such as magnesium stearate, sodium stearate and other metallic stearates, glycerol stearate stearic acid, silicone fluid, talc waxes, oils and colloidal silica. Flavouring agents such as peppermint, oil of wintergreen, cherry flavouring and the like can also be used. It may be desirable to add a colouring agent to make the dosage form readily identifiable. Tablets may also be coated by methods well known in the art.

A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active agent in a free flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface-active or dispersing agent. Moulded tablets may be made by moulding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent.

The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active agent.

Other formulations suitable for oral administration include lozenges comprising the active agent in a flavoured base, usually sucrose and acacia or tragacanth; pastilles comprising the active agent in an inert base such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising the active agent in a suitable liquid carrier.

For topical application to the skin, compounds of general formula (I) may be made up into a cream, ointment, jelly, solution or suspension etc. Cream or ointment formulations that may be used for the drug are conventional formulations well known in the art, for example, as described in standard text books of pharmaceutics such as is the British Pharmacopoeia.

Parenteral formulations will generally be sterile.

Suitable dosage levels will be apparent to those skilled in the art. As an example, a dosage of ig administered intravenously WiW4O% is considered suitable. Similar levels administered by other routes are also considered appropriate.

As demonstrated with combinations of existing antibiotics, such as gentomycin with penicillin or trimethoprim with sulphamethoxazole, it is anticipated that the antibacterial agent of the present invention will exhibit synergistic effects in combination with other, known antibacterial agents.

When the compound of general formula (I) is intended for other uses, for example as a disinfectant or an antiseptic or for impregnating fabrics, it is not necessary for it to be pharmaceutically acceptable and therefore it may include a different range of carriers and solvents. Therefore, in a further aspect of the invention, there is provided a composition comprising a compound of general formula (I) together with a suitable carrier. Water is one such carrier.

In some circumstances for example in hospitals and particularly in isolation wards, it may be useful to provide bedding, furnishings and garments which have antibacterial properties. Therefore, in a further aspect of the invention, there is provided a fabric impregnated with a composition comprising a compound of general formula (I) as defined above.

For the second and further aspects of the invention, preferred features are as for the first aspect.

The invention will now be described in greater detail with reference to the examples and to the drawings in which: FIGURE 1 is a photograph of an agar plate seeded with a "lawn" of MRSA at an inoculum designed to create a "semi confluent" growth after incubation. A well has is been cut in the agar. A 1 in 100 dilution of DTPA (into sterile water) is put in the well.

The plate is incubated overnight. Next day the "zone of inhibition" can be seen where the DTPA has diffused through the agar in sufficient concentration to inhibit the growth or kill the MRSA. The rest of the MRSA "lawn" grows normally.

FIGURE 2 is a photograph similar to that of Figure 1 but showing the activity of DTPA against Drug Resistant Acinetobacter baumanii (DRAB).

FIGURE 3 is a photograph similar to that of Figure 1 but showing the activity of DTPA against VRE.

Example I -DTPA has Antibacterial Activity Against Drug Resistant Bacteria A blood agar plate supplied by bioMerieux was seeded with a "lawn" of MRSA at an inoculum designed to create a "semi confluent" growth after incubation.

A well was cut into the agar plate and this was filled with a Ito 100 dilution of DTPA in sterile water. The plate was incubated overnight at 37°C to allow the MRSA to grow. Figure 1 shows a photograph of the plate taken the following day when the DTPA has diffused through the agar in sufficient quantity to inhibit the growth of or kill the MRSA. It can be seen that in regions to which the DTPA has diffused, the MRSA grows normally.

Similar experiments were performed with cultures of DRAB and VRE and the results are shown in Figures 2 and 3.

From Figures 1 to 3, it can be seen that DTPA is active against all of the drug resistant bacteria.

Claims

CLAIMS1. A compound of general formula (I): 1 3R-R (I)wherein each of R1, R2 and R3 is independently selected from CH2C(O)OH or (CH2)mN(CH2C(O)OH)2; mis I to 3; or a salt thereof; for use in the treatment of bacterial or fungal infection.
2. A method for the treatment of bacterial infection, the method comprising administering to a patient in need of such treatment an effective amount of a compound of general formula (I) or a salt thereof as defined in claim 1.
3. The use of a compound of general formula (I) or a salt thereof as defined in claim 1 in the preparation of an agent for the treatment of bacterial infection.
4. A compound as claimed in claim 1, a method as claimed in claim 2 or the use as claimed in claim 3, wherein the bacterial infection is caused by bacteria found in hospita Is.
5. A compound, method or use as claimed in claim 4, wherein the bacterial infection is caused by bacteria resistant to one or more antibiotic agents.
6. A compound method or use as claimed in claim 5, wherein the bacterial infection is caused by meticillin resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, vancomycin resistant Enterococcus (VRE) or Extended Spectrum Beta-Lactamase producers (ESBLs).
7. A composition comprising a compound of general formula (I) or a salt thereof for use in the treatment of bacterial or fungal infection.
8. A composition as claimed in claim 7 which is a pharmaceutical composition comprising a compound of general formula (I) as an active agent together with a pharmaceutically acceptable excipient or carrier.
9. A pharmaceutical composition as claimed in claim 8 which is formulated for io oral, rectal, nasal, bronchial (inhaled), topical (including eye drops, buccal and sublingual), vaginal or parenteral (including subcutaneous, intramuscular, intravenous and intradermal) administration.
10. A composition as claimed in claim 7 which is a disinfectant composition.
11. A composition as claimed in claim 7 which is an antiseptic composition.
12. A composition as claimed in claim 7 which is suitable for impregnating fabrics.
13. A fabric impregnated with a composition comprising a compound of general formula (I) or a salt thereof as defined in claim 1 for use in the treatment of bacterial or fungal infection.
14. A composition as claimed in any one of claims 7 to 12 or a fabric according to claim 13, wherein the bacterial infection is caused by bacteria found in hospitals.
15. A composition or fabric as claimed in claim 14, wherein the bacterial infection is caused by bacteria resistant to one or more antibiotic agents.
16. A composition or fabric as claimed in claim 15, wherein the bacterial infection is caused by meticillin resistant Staphylococcus aureus (MRSA), Acinetobacter baumannll, vancomycin resistant Enterococcus (VRE) or Extended Spectrum Beta-Lactamase producers (ESBLs).
17. A compound, method, use, composition or fabric as claimed in any one of the preceding claims, wherein the compound of general formula (I) is diethylene triamine pentaacetic acid (DTPA), ethylene diamine tetraacetic acid (EDTA) or N,N-bis(carboxymethyl)glycine or Triglycollamic acid (NTA), also known as Trilone A.