CA2669594A1 - Clotrimazol for treating staphylococcal infections - Google Patents

Abstract

There is described clotrimazole, l-[(2-chlorophenyl) diphenylmethyl]-lH-imidazole (C22H17ClN2); and derivatives thereof, for the treatment of an infection caused by or contributed to a methicillin resistant Staphylococcus species. There is also described a method of treating a patient suffering from an infection caused by or contributed to a methicillin resistant Staphylococcus species, said method comprising the step of administering an effective amount of clotrimazole, and derivatives thereof.

Description

CLOTRIMAZOL FOR TREATING STAPHYLOCOCCAL INFECTIONS

FIELD OF THE INVENTION

The present invention provides medicaments and methods for the treatment of infections caused or contributed to by multi-drug resistant bacterial species.
BACKGROUND

Drug resistant microorganisms, especially bacteria, are becoming increasingly problematic as infection rates continue to rise and effective methods of control become more and more limited. Prolific use of antibiotics over the last 50 or so years together with the indiscriminate prescribing of antibiotics and patient non-compliance with treatment regimes, has selected for microorganisms that have developed or acquired ways of overcoming the effects of antibiotics. The transmission and control of drug-resistant organisms is becoming one of the most significant problems within healthcare.

Of particular note are strains of Staphylococcus that have developed or obtained varying levels of resistance to antibiotics such as methicillin (meticillin).
These strains are commonly known as methicillin resistant Staphylococcus aureus (MRSA).

In addition, coagulase-negative Staphylococci, such as Staphylococcus epidermidis, have also emerged as important nosocomial pathogens. Approximately 80% of S.
epidermidis isolates from device-associated infections are methicillin resistant (MRSE) as well as being multi-resistant. Resistance to multiple antibiotics and the ability of S. epidef=rnidis to form biofilms on inert surfaces exacerbate the challenges of treating infections caused by these organisms. The acquisition of methicillin resistance among Staphylococcal species not only precludes the use of all currently available (3-lactam antibiotics, but also is commonly associated with resistance to multiple drug classes.

Young, elderly and immunocompromised people/patients tend to be at most risk of contracting infections from methicillin resistant Staphylococcal strains.
Consequently, persistent infections caused or contributed to by drug resistant microorganisms, such as methicillin Staphylococci, are often contracted in hospitals and/or nursing homes where the frequent use of antibiotics has created an envirorunent particularly suitable for the survival of drug resistant microorganisms.
In addition, community-acquired MRSA (cMRSA) is also now being recognised as an increasing problem, with transmission occurring in public and social areas such as public gyms and sports centres.

MRSA and MRSE are genotypically and phenotypically distinct from other Staphylococci; tending to form discrete clonal lineages. The acquisition of large mobile genetic elements carrying virulence and resistance determinants by these strains results in staphylococci that are often resistant to a number of drugs.
Resistance can be specific, i.e. particular to a certain drug or class of drugs or non-specific in that the resistance applies to a range of drugs, not necessarily related.
Methicillin resistant Staphylococci may be defined as Staphylococci that harbour the mecA gene. Expression of this gene yields PBP2a which confers resistance to all currently available (3-lactam antibiotics. The presence of the gene or protein product may be detected by polymerase chain reaction (PCR) or latex agglutination assay respectively. The mecA gene and its regulators are present on a large DNA
elements (SCCmec) which often carry other resistance and virulence genes. The management of infections caused by methicillin resistant Staphylococcal species, reflect these genotypic and phenotypic differences, and requires greater investment in hospital infrastructure, facilities for patient isolation, and infection control measures than for other strains of Staphylococci.

Conventionally, vancomycin, a glycopeptide antibiotic, is used to treat MRSA
infections. However, it is disadvantageous in that, inter alia, it has low oral absorption. Furthermore, vancomycin is also found to be inferior in terms of its efficacy compared to antistaphylococcal penicillins. Therefore, the treatment options for infections contributed to or caused by methicillin resistant bacteria such as MRSA
and MRSE, are now limited and there is an urgent need to discover new compounds which inhibit or kill such organisms.

Lee, et al, in J. Microbiol. Biotechnol. 9 (1999) 572-575, reported that miconazole was estimated to have a minimum inhibitory concentration of 0.78 g/ml against MRSA. However, the anti-MRSA activity of miconazole was completely suppressed by lipophilic a-tocopherol (vitamin E).

An objective of the present invention is to provide a new and effective treatment for infections caused or contributed to by methicillin resistant Staphylococci.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides clotrimazole or a derivative thereof, for treatment of an infection caused or contributed to by a methicillin resistant Staphylococcus species.

The present invention encompasses clotrimazole for treating infections caused or contributed to by methicillin resistant strains of Staphylococcus such as, for example, Staphylococcus aureus and/or Staphylococcus epidermidis. Such strains may commonly be known as methicillin resistant Staphylococcus aureus (MRSA) or methicillin resistant Staphylococcus epidermidis (MRSE). While MRSA and MRSE
may be defmed as being resistant to methicillin, they may also be resistant to other types of antibiotic particularly those belonging to the (3-lactam family such as flucloxacillin and oxacillin. It should be noted that the Staphylococcal strains encompassed by this invention may also be resistant to other antibiotics not mentioned here.

It is a surprising aspect of the present invention that of the large number of therapeutically effective imidazoles that are commercially available, only clotrimazole has been found to be efficacious in the treatment of an infection caused or contributed to by a methicillin resistant Staphylococcus species. We have found that other imidazoles structurally more closely related to miconazole, such as ketoconazole, did not inhibit the growth of Staphylococcus species as is illustrated in Table 2.

In addition, the present invention also encompasses uses of various salts and therapeutically active addition salts of clotrimazole and derivatives of clotrimazole; in particular, clotrimazole nitrate (Ca2H17CIN2 = HN03).

It may be convenient or desirable to prepare, purify, and/or handle a corresponding solvate of the compounds described herein, which may be used in any one of the uses/methods described. The tenn solvate is used herein to refer to a complex of solute, such as a compound or salt of the compound, and a solvent. If the solvent is water, the solvate may be termed a hydrate, for example a mono-hydrate, di-hydrate, tri-hydrate etc, depending on the number of water molecules present per molecule of substrate.

Furthermore, and in a second aspect, the present invention provides a method of treating a subject suffering from an infection caused or contributed to by a methicillin resistant Staphylococcus species, said method comprising the step of administering an effective amount of a compound comprising clotrimazole, or a derivative thereof.

Furthermore, the present invention encompasses a method of treating an infection caused or contributed to by a methicillin resistant Staphylococcus species, said method comprising the step of administering an effective amount of clotrimazole or clotrimazole nitrate.

Advantageously, compounds comprising clotrimazole and/or a derivative thereof may be administered orally, topically to the site of an infection, or intravenously.
Z5 Accordingly, compounds comprising clotrimazole and/or a derivative thereof may be formulated as polymeric nanoparticles such as alginate or polylactide-co-glycolide nanoparticles, or as sterile pharmaceutical compositions comprising a pharmaceutically acceptable carrier or excipient. Such carriers or excipients are well known to one of skill in the art and may include, for example, water, saline, phosphate buffered saline, dextrose, glycerol, ethanol, ion exchangers, alumina, aluminium stearate, lecithin, serum proteins, such as serum albumin, buffer substances such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, lactic acid, water salts or electrolytes, such as protamine sulphate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cyclodextrins, such as a-cyclodextrin, 0-cyclodextrin, sulfobutylether7-(3cyclodextrin and hydroxypropyl-(3-cyclodextrin, cellulose-based substances, polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes, polyethylene-polypropylene-block polyiners, polyethylene glycol and wool fat and the like, or combinations thereof.

Clotrimazole is well absorbed in humans following oral administration and is eliminated mainly as inactive metabolites. Oral administration of 1.5-3-g doses of clotrimazole gave a half-life of around 3 hours; single or twice daily oral administration may be suitable for the treatment of multiresistant staphylococcal infections with clotrimazole. Less than 1% of the adininistered dose was detected in urine as active drug after 6 hours.

A clotrimazole topical solution containing, for example, 10 mg/ml (1%) clotrimazole would be suitable for the treatment of multi-resistant staphylococci. Six hours after the application of clotrimazole 1% cream and 1% solution onto intact and acutely inflamed skin, the concentration of Clotrimazole varied from 100 jig/cm 3 in the stratum corneum to 0.5 to 1 jig/cm3 in the stratum reticulare, and 0.1 g/cm3 in the subcutis. Gentle massage of sufficient clotrimazole topical solution into the affected and surrounding skin areas twice a day, in the morning and evening, is suggested for the treatment of multidrug resistant staphylococcal infections.

Compounds comprising clotrimazole or a derivative thereof may be administered in combination with another treatment. For example, compounds comprising clotrimazole and/or a derivative thereof may be administered in combination with another antibiotic, for example vancomycin, to reduce the likelihood of emergence of antibiotic resistance, or antifungal or antiviral, agents or compounds.
Additionally or alternatively, clotrimazole and/or a derivatives thereof may be administered in combination with a chemotherapeutic agent, an immunostimulatory compound or drug, an oligonucleotide, a cytokine, hormone or the like.

It may be possible to administer a compound comprising clotrimazole and/or a derivative thereof or any combined regime as described above, transdennally via, for example, some form of transdermal delivery device. Such devices are advantageous, particularly for the administration of antibiotic compounds, as they may allow a prolonged period of treatment relative to for example, an oral or intravenous medicament.

Examples of transdermal delivery devices may include, for example, a patch, dressing, bandage or plaster adapted to release a compound or substance through the skin of a patient. A person of skill in the art would be familiar with the materials and techniques which may be used to tran.sdermally deliver a compound or substance and exemplary transdermal delivery devices are provided by GB2185187, US3249109, US3598122, US4144317, US4262003 and US4307717.

By way of example, clotrimazole and/or a derivative thereof may be combined with some form of matrix or substrate, such as a non-aqueous polymeric carrier, to render it suitable for use in a transdermal delivery system. The clotrimazole (and/or derivative)/matrix or substrate mixture may be further strengthened by the use of a woven or knit, non-woven, relatively open mesh fabric, to produce a patch, bandage, plaster or the like which may be temporarily attached to a particular region of a patient's body. In this way, while in contact with a patient's skin, the transdermal delivery device releases the compound or substance directly to the site of infection or through the skin as required.

Advantageously, the medicaments and/or methods described herein may have particular application in institutions housing, sheltering, caring or otherwise holding people or patients vulnerable to or "at risk" of developing or contracting a methicillin resistant Staphylococcus species, especially for example MRSA or MRSE. The medicaments and methods may be particularly useful in hospitals, nursing homes, nurseries and/or schools. More generally, an elderly, young or immunocompromised person or patient may particularly benefit from the medicaments and methods described herein. Moreover, the methods and medicaments of the present invention may be particularly useful to those undergoing a prolonged stay in hospital, for example in an intensive care facility.

Additionally, or alternatively, the medicaments and methods described herein may be useful in community centres, sports facilities, shops, restaurants, cafes or other places where transmission of bacteria, particularly methicillin resistant Staphylococcus species, is likely.

In a furtlier embodiment, the methods and medicaments described herein may be used prophylactically as a means to prevent the development of an infection caused or contributed to by a methicillin resistant Staphylococcus species. Medicaments and/or methods for prophylactic use may be administered or applied to any person at risk of developing an infection caused or contributed to by a methicillin resistant Staphylococcus species. For example, people working in care homes, nursing homes, sports centres, community centres, shops, restaurants, cafes, nurseries and/or schools may require prophylactic treatments.

The compounds provided herein may also be used as sterilising or cleaning aids for use, for example, on surfaces to reduce and/or eliminate contamination by methicillin resistant Staphylococcus species such as MRSA or MRSE. By way of example, clotrimazole or derivatives thereof such as, for example clotrimazole, may be prepared for application to any surface suspected of being contaminated by methicillin resistant Staphylococcus species. For example, compounds of the present invention may be added to or diluted in an appropriate excipient or solution prior to use as a sterilising or cleaning agent. Exemplary excipients are described above. Such sterilising or cleaning solutions may be used to decontaminate, for example, furniture, floors, equipment including for example specialised hospital equipment and/or surgical equipment.

In particular, the . present invention concerns the use of clotrimazole, or a derivative thereof, in the manufacture of an antibacterial agent against methicillin resistant Staphylococcus species.

In a further embodiment, the compounds described herein may be used to eliminate and/or reduce contamination by methicillin resistant Staphylococcus species on parts of the body, particularly for example, the hands. Clotrimazole and/or a-derivative thereof, may be diluted as an aqueous or non-aqueous solution (dissolved in aqueous, non aqueous or organic solvent) and which may be applied to a body part, for example the hands. Such a solution may find particular application in, for example hospitals, care homes and or nurseries where the prevalence and transmission rates of methicillin resistant Staphylococcus species are often high.

DETAILED DESCRIPTION
METHODS

In example experiments, clotrimazole was dissolved in methanol. Other solvents that may be used include caster oil, pyridine, DMSO and 0.9% saline. For IV
administration agents may be solubilised in polyethoxylated caster oil, or cyclodextrins such as sulfobutylether7-ocyclodextrin or hydroxypropyl-(3-cyclodextrin and lactic acid. Minimum inhibitory concentrations (MICs) of a range of clinical and control bacterial organisms were measured according to BSAC (British Society for Antimicrobial Chemotherapy) guidelines, described briefly as follows;

PREPARATION OF AGAR PLATES AND BROTHS.

Stock solutions of each agent were prepared using the formula:
1000xVxC=W
P
Where P jig of active compound per mg ( g/mg) V = volume required (mL) C final concentration of solution (mg/L) W= weight of agent (mg) to be dissolved in volume V (mL) Stock solutions were prepared at concentrations of 1000mg/L and 100mg/L. The appropriate amounts of each stock solution were added to separate Petri dishes to give the following final concentrations (after the addition of 20mL molten agar):
128, 64, 32, 16, 8, 4, 2, 1, 0.5, 0.25, 0.12, 0.06, 0.03, 0.015mg/L.

Volumes (2OmL) of cooled molten IST agar (oxoid) was added to each Petri dish and mixed by swirling.

After drying, the plates were stored at 4 C and protected from light. Plates were used on the day of preparation.

PREPARATION OF INOCULUM

The test organisms were grown overnight in 5mL IST broth. Using a dilution in 0.9%
saline of 1:500 for Gram-negative organisms and 1:100 for Gram-positive organisms, the appropriate agar plates were inoculated using a multipoint inoculator.

INCUBATION

Plates were incubated at 37 C in air for 18-20 hours.
INTERPRETATION OF RESULTS

The MIC is the minimum amount of an antibiotic at which there is no visible growth of bacteria. Tiny single colonies or faint hazes were not counted as growth.
RESULTS

Clotrimazole demonstrated good activity against S. epidernais and a range of clinical MRSA strains (Table 1), but had no significant activity against Gram-negative organisms. Other related imidazoles did not inhibit the growth of any strain tested (Table 2).

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Claims (28)

1. Clotrimazole, 1-[(2-chlorophenyl) diphenylmethyl]-1H-imidazole (C22H17ClN2); and derivatives thereof, for the treatment of an infection caused by or contributed to a methicillin resistant Staphylococcus species.

2. Clotrimazole according to claim 1 wherein the methicillin resistant Staphylococcus species is selected from the group consisting of MRSA and MRSE.

3. Clotrimazole according to claim 3 wherein the methicillin resistant Staphylococcus species is one or more of MRSA and MRSE.

4. Clotrimazole according to claim 1 wherein the clotrimazole derivative is a salt.

5. Clotrimazole according to claim 4 wherein the salt is a nitrate.

6. Clotrimazole according to claim 4 wherein the clotrimazole is selected from the group consisting of clotrimazole and clotrimazole nitrate.

7. Clotrimazole according to claim 1 wherein the clotrimazole is suitable for transdermal administration.

8. Clotrimazole according to claim 1 wherein the clotrimazole is suitable for administration in combination with an additional therapeutic agent.

9. Clotrimazole according to claim 8 wherein the additional therapeutic agent is selected from one or more of an antibiotic agent, an antifungal agent, an antiviral agent, a chemotherapeutic agent, an immunostimulatory agent, an oligonucleotide, a cytokine an hormone.

10. Clotrimazole according to claim 1 wherein the method comprises the prophylactic use of clotrimazole.

11. A method of treating a patient suffering from an infection caused by or contributed to a methicillin resistant Staphylococcus species, said method comprising the step of administering an effective amount of clotrimazole, and derivatives thereof.

12. A method according to claim 11 wherein the methicillin resistant Staphylococcus species is selected from the group consisting of MRSA and MRSE.

13. A method according to claim 12 wherein the methicillin resistant Staphylococcus species is one or more of MRSA and MRSE.

14. A method according to claim 11 wherein the clotrimazole derivative is a salt.

15. A method according to claim 14 wherein the salt is a nitrate.

16. A method according to claim 14 wherein the clotrimazole is selected from the group consisting of clotrimazole and clotrimazole nitrate.

17. A method according to claim 11 wherein the clotrimazole is suitable for transdermal administration.

18. A method according to claim 11 wherein the clotrimazole is suitable for administration in combination with an additional therapeutic agent.

19. A method according to claim 18 wherein the additional therapeutic agent is selected from one or more of an antibiotic agent, an antifungal agent, an antiviral agent, a chemotherapeutic agent, an immunostimulatory agent, an oligonucleotide, a cytokine an hormone.

20. A method according to claim 11 wherein the method comprises the prophylactic use of clotrimazole.

21. The use of clotrimazole, and derivatives thereof, in the manufacture of an antibacterial agent against methicillin resistant Staphylococcus species.

22. The use according to claim 21 wherein the methicillin resistant Staphylococcus species is selected from the group consisting of MRSA and MRSE.

23. The use according to claim 22 wherein the methicillin resistant Staphylococcus species is one or more of MRSA and MRSE.

24. The use according to claim 21 wherein the imidazole derivative is a salt.

25. The use according to claim 24 wherein the salt is a nitrate.

26. The use according to claim 24 wherein the imidazole is selected from the group consisting of clotrimazole and clotrimazole nitrate.

27. The use according to claim 21 wherein the antibacterial agent is a sterilising or cleaning agent.

28. The clotrimazole, method or use substantially as hereinbefore described with reference to the accompanying examples.