HK1232405B - A liquid antimicrobial composition - Google Patents

Description

Liquid antimicrobial composition

The present invention relates to liquid antimicrobial compositions, in particular to compositions for use in disinfecting the skin of a human or animal, which may require disinfection of drug tolerant organisms.

Skin disinfection is required prior to surgery to break the skin barrier and allow entry of microorganisms that may cause infection. These microorganisms may be external contaminants from the environment or equipment, or may be normal commensal skin colonies, while harmless in normal external situations, but may cause serious infections in the body. It would also be beneficial to provide a method of cleaning and disinfecting the skin of a hospital patient who is unable to bath or shower.

Many agents have been used on the skin for these purposes. In the past, calcium chloride and other chlorine donor chemicals were used, but these were highly aggressive and damaging to the skin. Recently, agents such as iodophors, povidone-iodine, alcogels, aqueous chlorhexidine and alcoholic chlorhexidine formulations have been used. Alcohol alone, whether ethanol or propan-2-ol, is an effective skin disinfectant, but the duration of the effect is short. Currently, the alcohol-containing chlorhexidine is a widely used agent of choice because it combines the cationic residue and long-lasting antimicrobial activity of chlorhexidine with the activity of alcohol. The combination of 70% alcohol with 2-4% chlorhexidine appears to be highly effective and is widely used globally, especially for small surgical site disinfection and the disinfection requirements associated with central line and intravenous catheter cannulas.

Chlorhexidine and other cationic disinfectants are also widely used in water-based skin care formulations, such as patient bed bath wipes, preoperative skin disinfection products in the form of liquids or wipes, and antibacterial shampoo caps and formulations. Their excellent spectrum of antimicrobial activity combined with excellent residual activity and relative safety are the main reasons for the success of these products.

However, although highly effective and beneficial products in health care, the health care community has recently noted increased tolerance to chlorhexidine and an increasing number of strains that are resistant to chlorhexidine. This is a serious problem. Although a smaller increase in the level of tolerance was noted in the concentration compared to the 2-4% level applied to the skin; this low level increases the importance of the putative chlorhexidine because of the overall mechanism of action involving prolonged residual activity and the continued presence of very low residual concentrations on the skin. If the bacterial tolerance is increased, the residual active effect of chlorohexidine will be seriously impaired. Concerns have been raised regarding increased skin allergic reactions to chlorhexidine, even chlorhexidine-induced allergic cases.

Organisms have resulted in increased tolerance to chlorhexidine and other cationic biocides by means of mutations and selection of those with greater effectiveness in efflux pump mechanisms. Efflux pumps are proteins encoded by genes such as qacA and cepA, embedded in the bacterial cytoplasmic membrane. Its function is to identify toxic, potentially harmful agents that penetrate the cell wall and reach the periplasm or cytoplasm. The efflux pump then extrudes and expels the reagents to the external environment before they reach their target. Thus, efflux pumps are transporters of harmful compounds from within bacterial cells to the external environment. This can be achieved by using energy from Adenosine Triphosphate (ATP) or proton motive force (pmf). So-called ABC transporters use ATP directly and RND-type efflux pumps use hydronium pH gradients. Efflux pump expression and enhancement can be due to chromosomal mutations or plasmid acquisition. Overexpression of efflux pump mechanisms leads to increased tolerance of cell membrane-disrupting antimicrobial agents, which can lead to multidrug-resistant (MDR) strains.

The function of efflux pump mechanisms is understood by studies and the way these functions can be subsequently suppressed. Four major efflux pump inhibition mechanisms have been identified. They are set forth below.

1. Reducing the exposure of bacterial cells to ions such as Ca2+ that act as cofactors in the efflux pump.

2. The energy provided by the proton motive force potential (pmf) is suppressed.

3. The enzyme that provides the hydronium ion required to maintain the pmf is inhibited.

4. Competes with invasive deleterious agents in contact with efflux pumps, for example by non-specific blockade or bacterial outer membrane coating.

Not all of these efflux pump inhibition pathways are equally feasible in clinical applications that provide topical antimicrobial therapy.

In addition to chlorohexidine, other cationic microbiocides are known to be membrane active, which breakdown and/or penetrate the microbial cell membrane. Examples of these are polymeric biguanides such as polyhexamethylene biguanide (PHMB), polyhexamethylene biguanide hydrochloride, octenidine dihydrochloride and quaternary ammonium compounds. While some of these cationic microbiocides have not shown tolerance in the formation of efflux pump mechanisms, it is believed that inhibition of efflux pump mechanisms relative to these microbiocides is also beneficial.

It is therefore an object of the present invention to provide a liquid antimicrobial composition for use in the disinfection of human or animal skin that maintains the antimicrobial benefits of cell membrane-disrupting cationic microbiocides treating the skin while eliminating or mitigating the increased tolerance of microorganisms to form against it via the efflux pump pathway.

According to the present invention there is provided a liquid antimicrobial composition for use in disinfecting the skin of a human or animal comprising a cationic microbicide for disrupting cell membranes and a cationic dendrimer capable of inhibiting the efflux pump mechanism of said cell membranes.

Applicants have discovered that cationic dendritic polymers are capable of binding to and disrupting bacterial membranes to inhibit or disrupt efflux pump mechanisms. The addition of a dendritic polymer to the composition may also enhance the antiviral properties of the composition. Such dendrimers need not be sufficient per se to comply with regulatory regulations of microbicides, but because of their ability to inhibit the efflux pump mechanisms of microbial cell membranes, they significantly reduce the ability of the microorganisms to develop increased tolerance to cell membrane-disrupting cationic microbicides used in compositions therewith.

Also preferably, the cell membrane disrupting cationic microbiocide comprises any one of or a combination of chlorhexidine, polymeric biguanides, octenidine dihydrochloride, and quaternary ammonium compounds.

Preferably, the cationic cell membrane disrupting biocide is chlorhexidine in the form of a gluconate or acetate. Advantageously, the concentration of chlorhexidine in the composition is between 0.25% and 6.00% w/v. The concentration is a concentration suitable for use in topical disinfection for use on human and animal skin.

Dendrimers are repetitively branched molecules that are typically symmetric around a core. By controlling the nature and number of core groups, branching, and functional groups on the surface, dendrimers with a variety of physicochemical properties can be synthesized. There are many variations that are valuable to the present invention.

Dendrimers can also be divided into generations, meaning the number of repeated branching cycles that are performed during their synthesis. Each successive generation results in a dendrimer that is approximately twice the molecular weight of the previous generation. Lower generation dendrimers classified as generation 0 to generation 2 dendrimers (G0-G2) are flexible molecules with no discernable internal region, whereas medium-sized dendrimers of generation 3 (G-3) and generation 4 (G-4) typically have an internal space separated from the shell of the dendrimer. Very large generation 7 (G-7) and larger dendritic polymers are more like solid particles, having a very dense surface due to their shell structure. Higher generation dendrimers also have more exposed functional groups on the surface, enabling them to be tailored to a given application.

In the present invention, generation 0 to generation 3 dendrimers, more preferably generation 0 to generation 2 dendrimers are preferred, as they form a planar, so-called "starfish" like conformation and have been found to be more effective in disrupting efflux pump mechanisms or microorganisms than dendrimers of generation 4 and above.

The dendritic polymer may be a poly (propyleneimine) -functionalized quaternary ammonium, polylysine, a dendritic polymer with surface groups based on sugars, such as mannose or maltose. Other types of dendritic polymers of interest in the present invention include poly (amidoamine) or PAMAM dendritic polymers, especially those having surface amino groups. The core of the poly (amidoamine) or PAMAM dendrimer is a diamine, usually ethylenediamine, reacted with methyl acrylate, then another ethylenediamine, to give a generation 0 (G-0) PAMAM. The successive reactions produce higher generations.

Dendrimers of macromolecules typically produce solutions of low viscosity relative to the size of the molecule, and preferred compositions comprise 0.01% w/v to 2% w/v of the dendrimer. This range is particularly beneficial when the composition comprises a 2% to 4% solution of chlorhexidine.

Preferably, the composition is an aqueous or hydroalcoholic solution, dispersion or emulsion, for example with isopropanol.

The composition may also contain surfactants to provide cleaning and wetting properties, solvents with microbicidal properties such as alcohols, chelating agents which may be problematic to use in hard water. Emollients and skin conditioning chemicals may also be added to the composition, such as tocopherol acetate. Preservatives such as benzalkonium chloride and/or citric acid may also be added in suitable amounts.

Preferably, the composition comprises from 0.05% w/v to 5.00% w/v of a surfactant. Suitable surfactants are those characterized as di-or tri-block copolymers of ethylene oxide and propylene oxide, for example poly (ethylene oxide) -b- (propylene oxide) -b- (ethylene oxide), i.e. PEO-PPO-PEO block copolymers, terminated with hydroxyl groups. They are produced, for example, by the BASF company under the trade nameAnd (5) selling. Suitable surfactants sold by the company areP85. These block copolymer surfactants may be used alone as a single molecular weight product, for example selected from copolymers such as poloxamers, or as a combination of two or more such surfactants. Other suitable surfactants are polyethylene glycols (PEGs), such as PEG 40. These surfactants, alone or in combination, can in turn be combined with other types of surfactants, such as glucosides, polyglucosides, linear alcohol ethoxylates, and the like. Nonionic surfactants are particularly preferred.

Furthermore, it is preferred that a significant proportion of the surfactants have a hydrophilic-lipophilic balance (HLB) value of from 10 to 17. These surfactants are water-soluble and those with HLB values above 12 are used as oil-in-water emulsifiers. It is beneficial if the composition is an aqueous solution and is formulated to contain essential oils or essential oil components as surfactants (e.g., polyethylene glycol) for distribution of the essential oils throughout the solution.

Wetting agents such as polysorbate 20 and nonionic lathering surfactants such as caprylyl/decyl glucoside may also be added to the composition.

In the formulation of compositions in aqueous or hydroalcoholic solutions, surfactant-forming micelles are undesirable, which can reduce the efficacy of the composition as an efflux pump inhibitor. Therefore, the concentration of the surfactant is preferably not higher than the critical micelle concentration thereof. Advantageously, the concentration of surfactant is at least 10% below its critical micelle concentration.

In addition, natural and synthetic polycations can play a useful role in the compositions of the present invention. Examples of synthetic polycations are e.g. poly (allylamine) hydrochloride, polyhexamethylene biguanide hydrochloride, poly (diallylmethylammonium chloride), poly (ethyleneimine) and polyvinylpyrrolidone. Examples of natural polycations are poly-L-ornithine, poly-L-arginine, protamine and chitosan.

Chelating agents such as etidronic acid (1-hydroxyethane 1, 1-diphosphonic acid (HEDP)), ethylenediamine, di-or tetraacetate, phosphonate, nitriloacetate (nitriloacetate) or others may also be added to the composition as possible essential oils or selected essential oil components. Preferably, the chelating agent is used in an amount of 0.05% w/v to 1.00% w/v of the composition.

As noted above, it is preferred to include an essential oil or essential oil component and a suitable solvent to disperse it throughout the composition. Suitable solvents include ethanol and polyethylene glycol, which may also be present in the form of the surfactants described above. The essential oil or essential oil component is preferably 0.01% w/v to 1.00% w/v of the composition.

The compositions of the present invention described above minimize the risk of developing antimicrobial resistance against the cell membrane-disrupting cationic microbiocides in the compositions. The branched polymer interacts with the cell membrane of the microorganism, resulting in a decrease in the microviscosity. It has been noted that in mammals, this is accompanied by inhibition of the activity of P-glycoprotein. It has been found that similar effects occur in bacteria with ABC efflux transporters that are structurally similar to P-glycoprotein (P-gp). The strong energy expenditure, the inhibition of efflux proteins and the subsequent ATP expenditure lead to the shutdown of the drug efflux system, thereby increasing the microbicide input; the organism is essentially sensitized to the microbicide.

Interference with the transport mechanism can be detected by membrane atpase assays and cellular calcein assays. Porin expression can also be detected by ethidium bromide or acridine orange technology, evaluating the efficacy of a particular formulation and its relevance to various aspects of patient care. Likewise, inhibition of efflux pump mechanisms will also have beneficial effects on biofilm production and quorum sensing of the microbial population. This will further improve the efficacy of the microbicide in the formulations contemplated by the present invention.

Other compounds may also be suitable for incorporation into the specific formulations of the present invention. In particular, compounds that inhibit efflux pump mechanisms are also useful. This is available from a variety of chemical groups including phenothiazine neuroactive drugs, certain essential oils and essential oil components such as berberine, Helichrysum italicum (R) italicum, geraniol, pinene, alpha zingiberine, terpenes, tea tree oil, and the like, as well as some complex surfactants.

To demonstrate the effectiveness of using dendrimers in inhibiting efflux pump mechanisms of tolerant microorganisms, the Minimum Inhibitory Concentration (MIC) of chlorhexidine digluconate against selected bacteria was tested and then compared to a chlorhexidine digluconate formulation comprising a cationic dendrimer. This method uses a double dilution (50% dilution) turbidity method for MIC determination. Detection byC and subsequent software from Thermo laboratory analysis, Inc, analyzed 2x 100 wells in an incubated spectrophotometer. With the selected bacteria, dual dilutions of chlorhexidine digluconate were prepared in the wells, with or without the addition of various cationic dendritic polymers in various combinations. The plates were incubated at 37 ℃ and the minimum inhibitory concentration was determined by densitometry at regular intervals over a 24 hour period.

The bacterium selected for detection is pseudomonas aeruginosa because its genome includes the desired gene (cepA). This test protocol was employed because it enables the immediate determination of multiple formulations. Thus, the method enables comparison of chlorhexidine digluconate controls with formulations comprising cationic dendritic polymers when treated with the same conditions.

Initial tests were performed to determine the MIC of chlorhexidine digluconate alone and the negative control, eliminating potential interference with other chemical components in the formulation. No significant difference was observed between the chlorhexidine digluconate alone and the chlorhexidine digluconate containing formulation excluding the cationic dendritic polymer. It can be seen that the best results are obtained with a combination of chlorhexidine digluconate, branched polymer and block copolymer. However, while tests demonstrate the effectiveness of the branched polymer and branched polymer block copolymer formulations, not all formulations are equally effective.

Four formulations tested are shown below, two aqueous solutions and two hydroalcoholic solutions. Double dilution of chlorhexidine digluconate concentration. In the formulation, only the block copolymer and the branched polymer are unchanged, i.e. they are not diluted. The results of the tests are shown graphically in the accompanying figures, where figures 1 and 2 are the MIC results for chlorhexidine digluconate alone and in combination with a cationic branched polymer. The four formulations used in the test are as follows.

1.0 generation (G-0) branched polymer

2.0 generation (G-0) branched polymers

3. Generation 1 (G-1) branched polymer

4. Generation 1 (G-1) branched polymer

In addition to the above-described test formulations, other preferred embodiments of the formulation of the antimicrobial composition according to the present invention are described below.

Example 1

Chlorhexidine gluconate 2.00% w/v

PEO-PPO-PEO block copolymer 1.00% w/v

Polypropylene Imine (PPI) branched Polymer 0.01% w/v

Ethylenediaminetetraacetic acid disodium salt

(disodium EDTA) 0.05% w/v

Water to 100%

Example 2

Chlorhexidine gluconate 2.00% w/v

Polypropylene Imine (PPI) branched Polymer 1.00% w/v

PEO-PPO diblock copolymer 0.05% w/v

HEDP 0.02％

70 percent of ethanol

Water to 100%

Example 3

Chlorhexidine gluconate 4.00% w/v

Geraniol 1.00% w/v

Polylysine branched polymer 0.05% w/v

Polyhexamethylene biguanide hydrochloride 0.50% w/v

0.20% w/v phenoxyethanol

PEG 40 0.50％w/v

Water to 100%

Example 4

Benzalkonium chloride 1.00% w/v

Cetyl pyridinium chloride 0.50% w/v

Cationic branched Polymer 1.00% w/v

Capryloyl glucoside surfactant 0.05% w/v

PEO/PPO block copolymer surfactant 0.50% w/v

Water to 100%

Example 5

Octenidine dihydrochloride 2.00% w/v

PAMAM branched Polymer 1.00% w/v

Polysorbate 200.50% w/v

Glycerol 1.00% w/v

Aloe 0.50% w/v

Essential oil based fragrance 0.10% w/v

EDTA disodium salt 0.05% w/c

Water to 100%

Example 6

Chlorhexidine gluconate 2.5% w/v

70.0% w/v Isopropanol

Polypropylene imine branched Polymer 1.5% w/v

0.2% w/v phenoxyethanol

Water to 100%

It will be appreciated that formulations suitable for application to human skin may further comprise conventional ingredients such as emollients, fragrances and skin conditioning agents, depending on the properties desired in addition to disinfection. These preparations are suitably used as surgical scrub solutions, skin wound cleansers, preoperative skin preparations, hand antiseptic lotions and the like. In all cases, the preferred concentration of the cell membrane-disrupting cationic biocide is 0.25% w/v to 6.00% w/v. Other similar applications include those in veterinary and animal husbandry, such as daily hygiene products, especially hygiene preparations prior to milking and teat dipping.

The compositions of the present invention may be used in conjunction with wipes, sponges, and composites such as shampoo caps, which are woven, knitted, or non-woven materials. Suitable wipes may be constructed from any of polyolefin, polyester, viscose, cotton, cellulose or other fibers, or mixtures thereof. The sponge wipe may be constructed of polyurethane. The composition may be absorbed by these composites, wipes or sponges and then packaged into packages suitable for dispensing from a tub, bucket, stream pack, plug or individually sealed wrap or capsule.

Claims (16)

1. Use of a cationic dendritic polymer in an aqueous or hydroalcoholic solution or dispersion of a liquid antimicrobial composition for use in skin disinfection of humans or animals for inhibiting the efflux pump mechanism of cell membranes for the control of bacteria for non-therapeutic purposes,

wherein the composition further comprises: a cell membrane disrupting cationic biocide which is chlorhexidine in the form of a gluconate or acetate present at a concentration of 0.25% to 6.00% w/v;

wherein the cationic dendrimer is a generation 1 dendrimer and is present in the composition at a concentration of 0.01% w/v to 2% w/v,

wherein the cationic dendritic polymer is any one or combination of quaternary ammonium functionalized poly (propyleneimine), Polyamidoamine (PAMAM) dendritic polymer, polylysine, and dendritic polymer having saccharide based surface groups.

2. Use according to claim 1, wherein said dendritic polymer is a poly (propyleneimine) or Polyamidoamine (PAMAM) dendritic polymer.

3. Use according to claim 1, wherein the composition additionally comprises a surfactant.

4. The use according to claim 3, wherein the surfactant is a poloxamer triblock copolymer surfactant.

5. Use according to claim 3, wherein the surfactant has a Hydrophilic Lipophilic Balance (HLB) value of from 10 to 17.

6. Use according to claim 3, wherein the surfactant is present at a concentration of at least 10% below its critical micelle concentration.

7. Use according to claim 3, wherein the surfactant is present in the composition at a concentration of 0.05% w/v to 5.00% w/v.

8. Use according to claim 1, wherein the composition additionally comprises a chelating agent.

9. The use of claim 8, wherein the chelating agent comprises any one or a combination of etidronic acid (1-hydroxyethane 1, 1-diphosphonic acid (HEDP)), ethylenediamine, di-or tetraacetate, phosphonate and nitriloacetate.

10. Use according to claim 8, wherein the chelating agent is present in the composition at a concentration of 0.05% w/v to 1.00% w/v.

11. Use according to claim 1, wherein the composition additionally comprises an essential oil or an essential oil component in combination with a solvent therefor.

12. Use according to claim 11, wherein the solvent is ethanol or polyethylene glycol.

13. The use according to claim 11, wherein the essential oil or essential oil component comprises any one or combination of berberine, Helichrysum italicum, geraniol, pinene, alpha zingiberine, terpene and tea tree oil.

14. Use according to claim 11, wherein the concentration of the essential oil or essential oil component in the composition is from 0.01% w/v to 1.00% w/v.

15. The use of claim 1, wherein the composition is combined with a wipe, sponge, or shampoo cap.

16. Use according to claim 1, wherein the composition disinfects human or animal skin by topical application.