HK1261602A1 - A deodorant composition and a method for preparing thereof - Google Patents

Description

Deodorant composition and process for producing the same

Technical Field

The present invention relates to a composition for use in a deodorant for a body part of a subject, and in particular, but not exclusively, to a deodorant formulation comprising a low skin irritation or reduced skin irritation composition.

Background

Body odor generally refers to the situation where an unpleasant or malodorous smell is released from a body part of a human subject or the skin of a body part. Although body malodour is known to be affected by various physiological conditions, it is often associated with sweat or perspiration of the subject, and the subsequent bacterial breakdown of organic compounds present in the sweat to form malodours with volatile organic acids. Thus, body malodour is most commonly produced at the axillary regions of the body, such as the axillary regions where there are a large number of sweat glands, but body malodour may also be produced at other parts of the human body, such as the palms, soles, upper thighs and back regions.

Various deodorant compositions and/or formulations have been developed to reduce, alleviate, eliminate or mask malodors and/or inhibit or stop the production of perspiration from the skin of a body part. In general, deodorants can be used by providing an antibacterial effect that inhibits bacterial decomposition; inhibiting or stopping perspiration by incorporating an antiperspirant; and/or by the introduction of fragrances to mask the odor produced. Deodorant formulations can be presented in different forms, such as solids, gels, creams, liquids or aerosols for various applications, such as application or roll-on sticks or rolls, body sprays or even body wipes; and may be classified as a cosmetic or pharmaceutical product depending on the particular active ingredient in the composition. Many commonly used deodorant actives include alcohols, triclosan, sodium stearate, Ethylene Diamine Tetraacetic Acid (EDTA), chlorhexidine, formaldehyde, and the like because of their antimicrobial function; and/or aluminum or zinc salts such as aluminum chloride, aluminum chlorohydrate, aluminum-zirconium compounds, and the like as antiperspirants. In addition to these commonly used active agents, hexamine, also known as hexamethylene tetramine (or methenamine), has been found to be an effective deodorant, although the mechanism of deodorization is well understood. However, hexamine-containing deodorant formulations have also been reported to cause skin irritation to the user, which may be potentially associated with formaldehyde emissions from hexamine in use.

Object of the Invention

It is an object of the present invention to provide a novel composition for reducing, suppressing or inhibiting the generation of malodours from a body part of a human subject.

It is another object of the present invention to provide a composition for use in a deodorant formulation that has reduced or reduced skin irritation.

It is a further object of the present invention to alleviate or eliminate, to some extent, one or more of the problems associated with known deodorant compositions and/or formulations, or at least to provide a useful alternative.

The above object is achieved by a combination of the features of the main claim; the dependent claims further disclose advantageous embodiments of the invention.

Other objects of the present invention will be obtained by those skilled in the art from the following description. Accordingly, the foregoing description is not exhaustive and is intended to be illustrative of only some of the many objects of the invention.

Summary of The Invention

In general, the present invention provides a composition for reducing, suppressing or inhibiting malodor generated from a body part of a subject, such as but not limited to a human subject. In particular, the present invention provides a hexamine-containing composition for use in deodorant formulations that exhibits high efficacy in reducing, suppressing or inhibiting the production of malodor associated with perspiration via a multifunctional deodorizing mechanism, with low or reduced skin irritation.

In a first broad aspect, the present invention provides a composition for reducing, suppressing or inhibiting malodor generated from a body part of a subject. The composition comprises an effective amount of an active ingredient comprising one or more of hexamine, derivatives thereof, and compounds thereof. The composition further comprises a buffer system adapted to maintain the pH of the composition in the range of about 7.0 to about 11.0 when the composition is applied to a body part.

In a second main aspect, the present invention provides a deodorant formulation for use at a body part of a subject. The deodorant formulation comprises the composition of the first main aspect.

In a third broad aspect, the present invention provides a method of preparing a low skin irritation composition for reducing, suppressing or inhibiting malodor from a body part of a subject. The method comprises providing an effective amount of an active ingredient comprising one or more of hexamine, derivatives thereof, and compounds thereof; providing a buffer system adapted to maintain the pH of the composition in the range of about 7.0 to about 11.0 when the composition is applied to a body part; wherein the buffer system is adapted to substantially neutralize local acidity of the body part, thereby reducing or minimizing the production of skin irritating byproducts from the active ingredient.

The summary of the invention does not necessarily disclose all features necessary to define the invention; the invention may reside in subcombinations of the disclosed features.

Brief Description of Drawings

The foregoing and other features of the invention will be apparent from the following description of preferred embodiments, which are provided by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a flame ionization detector gas chromatography (GC-FID) chromatogram showing neutralization of 3-hydroxy-3-methyl-hexanoic acid (HMHA) by sodium hydroxide and hexamine; and is

FIG. 2 is a GC-FID chromatogram showing neutralization of hexanoic acid by hexamine.

Description of the preferred embodiments

The following description is intended only as an example to describe the preferred embodiments and is not limited to the combination of features necessary for carrying out the invention.

Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, agent, composition, preparation, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. In addition, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments.

The present invention relates to a composition for reducing, suppressing or inhibiting malodour, such as sweat-related malodour, generated from a body part of a subject, such as an animal subject or a human subject). In particular, the present invention provides a hexamine-containing composition for use in deodorant formulations that is low skin irritation or reduces skin irritation, which composition is capable of exhibiting high efficacy in reducing, arresting or inhibiting the production of sweat-related malodour. The compositions are generally suitable for use on any body part, such as the axillary region of the human body, including the axillary region where a significant number of sweat glands are present. However, those skilled in the art will appreciate that the present invention should not be limited to axillary applications, but is also applicable to any other suitable body part where perspiration may occur, which may include, but is not limited to, hands, feet, upper thighs, and/or back areas.

In the context of the present invention, the term "deodorant" is broadly meant to include any agent, composition, preparation, formulation and/or product suitable for reducing, deterring, preventing, inhibiting, eliminating, masking odors, and more specifically malodors; and the "deodorizing" effect can be achieved by any known and possible mechanism, such as, but not limited to, incorporating an antiperspirant, an antimicrobial, a disinfectant, or a fragrance in the composition. Thus, the term "deodorant" in the context of the present invention includes compositions and products in both cosmetic and pharmaceutical applications.

Hexamine, also known as hexamethylene tetramine or hexamethylene tetramine, has traditionally been used as a pharmaceutically active ingredient for controlling urinary tract infections by releasing formaldehyde and ammonia in acidic urine, wherein formaldehyde is an effective antibiotic for preventing bacterial growth in the urinary tract. Recently, there has been increasing interest in the use of hexamine as an active ingredient in deodorant formulations, although the relevant deodorizing mechanism has not been clearly understood. One widely accepted speculation is that hexamine releases formaldehyde with antimicrobial properties in the presence of sweat having a natural pH of about 4.0 to 7.0. However, it has also been revealed from the studies of the present invention that hexamine can still exhibit antibacterial effect when prepared under alkaline conditions. Furthermore, hexamine is itself a weak base and has been found in current research to be able to neutralize many odorous volatile organic acids that are typically formed by the bacterial breakdown of organic substances in sweat. In addition, the hexamine-containing composition of the present invention exhibits inhibition of the aminoacylase enzyme reaction, which is reported to be a mechanism by which organic substances in sweat are decomposed by bacteria and cause body odor. Finally, formaldehyde released from hexamine is known to form keratotic plugs at the distal sweat ducts that substantially prevent opening of the hair follicles, resulting in a significant reduction or inhibition of sweat release. Thus, hexamine has been found to perform a multifunctional role in reducing or suppressing malodor generation in deodorant compositions and/or formulations.

However, it has also been reported that hexamine-containing deodorant formulations can cause skin irritation. One possible cause of skin irritation may be related to the release of formaldehyde, which is considered a potential skin irritant, and is exacerbated especially when formaldehyde is present in high concentrations, such as in highly acidic environments, where hexamine decomposes to form formaldehyde as a by-product.

In the context of the present invention, the term "by-product" as used, for example, in relation to formaldehyde or any aldehyde, does not generally exclude all and/or exert any functional property thereof. For example, in one embodiment of the present invention, formaldehyde released from the decomposition of hexamine or hexane-containing ingredients can act as an auxiliary active to provide additional or support deodorization with hexamine or hexamine-containing active ingredients, depending on the particular composition, formulation and application.

Accordingly, one embodiment of the present invention relates to a deodorant composition for axillary application, for example, in a human subject. The composition comprises an effective amount of an active ingredient sufficient to reduce, counter, or suppress any generated malodor caused by perspiration at the body site. The active ingredient may comprise one or more of hexamine, derivatives thereof and compounds thereof. The composition also comprises a buffer system for stabilizing the active ingredient and thereby controlling or preventing the release of any aldehydes, such as formaldehyde, due to decomposition of the hexamine. The buffer system is adapted to maintain the pH of the composition in the range of about 7.0 to about 11.0, and preferably about 7.5 to about 10.0, after application of the composition to a body part. The buffer system also provides a slightly alkaline to alkaline environment for neutralizing odorous organic acids produced by the bacterial breakdown of organic compounds present in sweat, which further helps to mitigate any generated malodors.

In one embodiment, the buffer system may comprise one or more commonly known pH buffers adapted to provide the desired buffer range as described above, such that the hexamine or hexamine-containing active ingredient in the composition may be substantially stabilized and the effects of acidic sweat significantly minimized. The buffer system may comprise one or more of inorganic and organic compounds, such as, but not limited to, one or more of the following: 3-morpholinopropane-1-sulfonic acid (MOPS), 4- (2-hydroxyethyl) -1-piperazineethanesulfonic acid) (HEPES), 3- (cyclohexylamino) -1-propanesulfonic acid (CAPS), 3- [ [1, 3-dihydroxy-2- (hydroxymethyl) propan-2-yl ] amino ] -2-hydroxypropane-1-sulfonic acid (TAPSO), 2-amino-2- (hydroxymethyl) -1, 3-propanediol (Trizma), and phosphate compounds, and salts thereof, or combinations thereof. Preferably, the buffer system may comprise an aqueous buffer solution to facilitate aqueous formulation of the composition.

A number of specific formulations and their corresponding compositions are provided in table 1. For example, formulations E, F, G, I, J (7.5) and J (6.2) are hexamine-containing compositions buffered according to the invention, while formulations S and A are control experiments without a buffer system in the composition.

Table 1: formulations containing hexamine as deodorant active ingredient: formulations E, F, G, I, J (7.5) and J (6.2) were each prepared according to an embodiment of the invention using a buffer system, while formulations S and A were prepared as control experiments, i.e., without a buffer system.

The corresponding formaldehyde content 1 day after application of the formulation to the test subjects was also evaluated. In particular, it was found that formulations incorporating a buffering system exhibited a significant reduction in formaldehyde emissions. For example, formulation F exhibited less than 0.2% formaldehyde release (i.e., about 1.57mM) when used, which was about 26-fold less when compared to control formulation S (i.e., about 40mM formaldehyde) under the same test conditions. A significant reduction in formaldehyde has further been demonstrated to reduce or prevent potential skin irritation. For example, after 8 days of application, control formulation S, which released a much higher concentration of formaldehyde, was found to cause skin irritation to the animal subjects during the "repeat skin irritation test", whereas no skin irritation was observed when formulation J (7.5), which released a much lower concentration of formaldehyde (i.e., about 4.57mM) under the same test conditions, was used. The details of these studies are further elaborated in the experimental phase.

Preferably, the active ingredient of the composition may comprise from about 5 w/v% to about 40 w/v%, and preferably from about 30 w/v% to about 40 w/v% hexamine, relative to the total volume of the composition, such that the active substance will be provided in excess to ensure an effective concentration in the composition, despite any possible breakdown or wash-off by perspiration during actual use.

The composition may optionally include one or more adjuvants such as, but not limited to, one or more moisturizers or emollients for topical application, such as glycerin; an antioxidant; pH adjusting agents such as hydrochloric acid and ammonium carbonate, etc., as shown in the formulation of table 1. The composition may also include one or more additives for other purposes, such as, but not limited to, cosmetic agents such as perfumes or essential oils; a colorant; a preservative; a thickener; a stabilizer; a propellant; a solvent; a fragrance; a coolant; sunscreens, and the like. Those skilled in the art will appreciate that the compositions of the present invention should not be limited to any specific embodiment or exemplified formulation, but should also include any additions, modifications or alterations as are deemed suitable or appropriate.

Optionally, the composition may comprise one or more antibacterial and/or antifungal agents to further enhance the antibacterial effect, for example, disinfectants such as quaternary ammonium salts, or biocides such as chlorhexidine. The composition may also include one or more chelating agents such as ethylenediaminetetraacetic acid (EDTA) for inhibiting bacterial aminoacylase reactions known to produce odorous organic acids that cause malodor.

The present invention also relates to a deodorant formulation or agent for use at a body part of a subject, the deodorant formulation or agent comprising one or more of the compositions of the above embodiments. The deodorant is preferably applied topically or applied and may be provided in one or more formulations of known form, such as, but not limited to, a solid, gel, cream, powder, liquid, spray or disposable wipe, i.e., a fabric or tissue impregnated with the composition in liquid form.

The present invention may further relate to a method of preparing a low skin irritation or reduced skin irritation composition for reducing, suppressing or inhibiting malodor from a body part of a subject. In one embodiment, the method comprises the step of providing an effective amount of an active ingredient that may comprise one or more of hexamine, derivatives thereof, and compounds thereof. The method further comprises providing a buffer system adapted to maintain the pH of the composition in the range of from about 7.0 to about 11.0, and preferably from about 7.5 to about 10.0, when the composition is applied to a body part. The buffer system is adapted to substantially neutralize local acidity of a body part, including but not limited to acidity of natural sweat and/or acidity caused by any volatile organic acids produced by aminoacylase enzyme reactions during bacterial breakdown of organic matter from sweat. Neutralization of topical acidity thus reduces or minimizes the production of skin irritating byproducts, such as aldehydes or more specifically formaldehyde, from hexamine-containing active ingredients.

Experiment of

Preparation of specific formulations of the composition

The following examples illustrate exemplary methods or processes for preparing specific formulations of compositions, including formulations S, A, E, F, G, I, J (7.5) and J (6.2), as shown in table 1 above.

10mL of formulation S:

4g hexamine, 0.3mL glycerol, and 0.127g sodium bisulfite were added to a 20mL container. Deionized water was added to the vessel and the solution was stirred. 0.055mL of hydrochloric acid was added to the solution to form formulation S having a volume of 10 mL.

10mL of formulation A:

4g of hexamine was added to a 20mL vessel. Deionized water was added to form formulation a with a volume of 10 mL.

10mL of formulation E:

CAPS buffer solution (200mM) was first prepared by dissolving 4.43g CAPS powder in 100mL deionized or milli-Q water. The solution is then adjusted to a pH of 10.8-11.0 by addition of sodium hydroxide solution or hydrochloric acid solution.

3.5g hexamine and 0.5g ammonium carbonate were added to a 20mL container. The pH adjusted CAPS (200mM) buffer solution was then added to the vessel to form formulation E in a volume of 10 mL.

10mL of formulation F:

CAPS buffer solution (200mM) was first prepared by dissolving 4.43g CAPS powder in 100mL deionized or milli-Q water. The solution is then adjusted to a pH of 10.8-11.0 by addition of sodium hydroxide solution or hydrochloric acid solution.

4g hexamine and 0.3mL glycerol were added to a 20mL vessel. The pH adjusted CAPS (200mM) buffer solution was added to the vessel to form formulation F in a volume of 10 mL.

10mL of formulation G:

a MOPS buffer solution (200mM) was first prepared by dissolving 4.19g of MOPS powder in 100mL of deionized water or milli-Q water. The solution is then adjusted to a pH of 7.7-7.9 by addition of sodium hydroxide solution or hydrochloric acid solution.

4g hexamine and 0.3mL glycerol were added to a 20mL vessel. The pH adjusted MOPS (200mM) buffer solution was added to the vessel to form formulation G in a volume of 10 mL.

10mL of formulation I:

a MOPS buffer solution (200mM) was first prepared by dissolving 4.19g of MOPS powder in 100mL of deionized water or milli-Q water. The solution is then adjusted to a pH of 7.7-7.9 by addition of sodium hydroxide solution or hydrochloric acid solution.

4g of hexamine and 0.5g of ammonium carbonate were added to a 20mL container. The pH adjusted MOPS (200mM) buffer solution was added to the container to form formulation I in a volume of 10 mL.

10mL of formulation J (7.5):

a sodium phosphate buffer solution (200mM) was first prepared by dissolving 1.2g of sodium dihydrogen phosphate powder and 1.4g of disodium hydrogen phosphate powder in 100mL of deionized water or milli-Q water. The solution is then adjusted to a pH of 7.4-7.6 by addition of sodium hydroxide solution or hydrochloric acid solution.

4g hexamine and 0.3mL glycerol were added to a 20mL vessel. pH adjusted sodium phosphate (200mM) buffer solution was added to the vessel to form formulation J (7.5) in a volume of 10 mL.

10mL of formulation J (6.2):

a sodium phosphate buffer solution (200mM) was first prepared by dissolving 1.2g of sodium dihydrogen phosphate powder and 1.4g of disodium hydrogen phosphate powder in 100mL of deionized water or milli-Q water. The solution is then adjusted to a pH of 6.0-6.2 by addition of sodium hydroxide solution or hydrochloric acid solution.

4g hexamine and 0.3mL glycerol were added to a 20mL vessel. The pH adjusted sodium phosphate (200mM) buffer solution was then added to the vessel to form formulation J (6.2) in a volume of 10 mL.

2000mL of formulation J (6.2):

a sodium phosphate buffer solution (200mM) was first prepared by dissolving 24g of sodium dihydrogen phosphate powder and 28g of disodium hydrogen phosphate powder in 2000mL of deionized water or milli-Q water. The solution is then adjusted to a pH of 6.0-6.2 by addition of sodium hydroxide solution or hydrochloric acid solution.

800g hexamine and 60mL glycerol were added to a 5L vessel. The pH adjusted sodium phosphate (200mM) buffer solution was added to the vessel to form formulation J (6.2) in a volume of 2L.

Acid resistance

The acid resistance of the prepared formulations has been tested in synthetic ISO sweat at various pH and sweat amounts.

Acid resistance test at different pH

Formulations S, A, F, G and J (7.5) were mixed separately with synthetic ISO sweat (sodium chloride 0.5%, L-histidine 0.05%, sodium dihydrogen phosphate 0.22%, pH adjusted with hydrochloric acid solution or sodium hydroxide solution) at different pH in a 1:1 volume ratio. Each sample mixture was incubated for 3 hours and subsequently the formaldehyde released was detected by the purplad assay. The results from the assay are shown in table 2 below.

Table 2 formaldehyde content in formulations S, A, F, G and J (7.5) after incubation in ISO sweat at different pH. ([ HCHO)]_InitialRepresents the "initial formaldehyde concentration"; LOQ stands for "quantitative Limit")

The study revealed that even after incubation with acidic sweat, such as pH 4, no significant increase in formaldehyde content was found in the specific formulations comprising F, G and J (7.5) in a buffer system; whereas a significant increase of about 260% in formaldehyde content was observed in the control formulation a.

Acid resistance test at different volumes

To evaluate the acid resistance performance of a particular composition in the presence of excess sweat, formulations S, A, F, G and J (7.5) were each mixed with acidic ISO sweat at pH 4 in different volume ratios. Each sample mixture was incubated for 3 hours and subsequently the formaldehyde released was detected by the purplad assay. Controls were prepared by mixing and incubating the formulations tested with deionized water, and the experiments were performed in parallel. The results of the assay are shown in table 3 below.

Table 3 formaldehyde content in formulations S, A, F, G and J (7.5) after incubation in different volume percentages of acidic ISO sweat at pH 4. ([ HCHO ] stands for "Formaldehyde concentration")

In a test by mixing 25% without buffer formula a in acidic sweat (i.e. 75% acidic sweat), the mixture exhibited an over 400% increase in formaldehyde content when compared to a corresponding control experiment incubated in water; whereas the buffer formulation of the present invention, such as formulation J, did not show significant changes in formaldehyde content under the same test conditions.

Skin irritation

Formulations S and J (7.5) were further investigated in various standard test methods for skin irritation, which were carried out according to the requirements and conditions of the international standard. The test method comprises the following steps:

1) repeated skin irritation tests on test rabbits (test method 1: chapter six of cosmetic safety and technical standards, chapter 4 skin irritation/corrosion test, 2015; and test method 2: ISO10993-10:2010, medical device biological evaluation-part 10: irritation and skin sensitization testing);

2) skin sensitization test in test guinea pigs (test method 1: chapter six of cosmetic safety and technical standards, chapter 6 skin sensitization test, 2015; and test method 2: ISO10993-10:2010, medical device biological evaluation-part 10: irritation and skin sensitization testing);

3) human skin patch test (test method 1: safety and technical standards of cosmetics, ministry of health of the people's republic of China, 2015 edition; the test method 2: COLIPA (Walker A.P. et al: Test guides for Association of skin Compatibility of Cosmetic Finished Products in Man. food and chemical toxicology 34,1996, 651-660)).

A summary of the test results is shown in table 4 below.

TABLE 4 summary of skin irritation test results

Formulation J (7.5) of the present invention proved to cause no irritation in all the above tests performed under standardized test standards. Specifically, formulation J (7.5) was shown to cause no irritation in the "repeat skin irritation test" on the test rabbits 14 days after continuous application on the skin of the subjects; whereas for non-buffered formulation S, erythema was observed from day 8 and the study ended until day 14.

Enzyme inhibition

As previously mentioned, bacterial aminoacylase reactions are reported as one possible mechanism for causing sweat-related malodors in the human body. Specifically, malodors are produced due to the presence of volatile organic acids produced as a by-product of bacterial breakdown of organic matter, such as proteins from human sweat, by aminoacylase reactions. In the present study, it was found that this enzymatic reaction requires magnesium cations as an essential cofactor, and that the presence of hexamine would likely compete with the relevant enzyme for magnesium cations by chelating. Thus, similar to the use of chelating agents such as EDTA for antibacterial action, the aminoacylase enzyme activity will be significantly slowed or even inhibited in the presence of hexamine.

This was done for Corynebacterium striatum N by the formulation J (7.5) of the present invention_αThe inhibition of the-acyl-glutaminyl acylase was further confirmed, where a 39% -51% reduction in the enzyme activity was found. The results demonstrate that hexamine, in addition to known antibacterial properties, also acts in inhibiting odor-causing enzymatic reactions, thereby reducing or eliminating malodors.

Antibacterial ability

Formulations S, A, G and J (7.5) were evaluated for antimicrobial capability. The formulations were incubated with the respective one of the bacteria tested: corynebacterium striatum, corynebacterium diphtheriae, and staphylococcus epidermidis, which have been reported to cause human body axillary odor. Table 5 lists the corresponding Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) (in% hexamine).

TABLE 5 antimicrobial Capacity of formulations S, A, G and J (7.5).

All hexamine-containing formulations have demonstrated antibacterial effects against corynebacterium striatum, while formulation J (7.5) showed the most significant effect among the four samples tested, with antibacterial effects against all three bacteria tested.

Neutralization of odorous acids

Hexamine, which is weakly basic in nature, was incubated with two commonly known odorant acids, 3-hydroxy-3-methyl-hexanoic acid (HMHA) and hexanoic acid, and potential neutralization was studied by using a gas chromatograph with a flame ionization detector (GC-FID). Chromatograms showing neutralization of 3-hydroxy-3-methyl-hexanoic acid (HMHA) by sodium hydroxide and hexamine and of hexanoic acid by hexamine are shown in figures 1 and 2, respectively. The results demonstrate that hexamine is capable of neutralizing the odorous acid tested.

In summary, the present invention provides a novel composition for reducing, suppressing or inhibiting the generation of unpleasant odours, such as sweat-related malodours, from a body part of a subject. In particular, the present invention provides a hexamine-containing composition for use in deodorant formulations that exhibits high efficacy in reducing, arresting or inhibiting the production of sweat-related malodour via a multifunctional deodorizing mechanism, with low or reduced skin irritation. The beneficial low skin irritation is provided by a buffer system included in the composition that substantially stabilizes hexamine in acidic sweat. The buffer system significantly reduces formaldehyde, a skin irritant, known from the decomposition and subsequent release of hexamine. The buffer system also provides a secondary neutralization of any odorous acids that have been generated by the bacterial breakdown of organic matter in sweat, which further helps to mitigate or prevent the generation of malodors.

This description illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope.

Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass structural, compositional, and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any way. It can be appreciated that any feature described herein can be used with any embodiment. The illustrative embodiments are not mutually exclusive or exclude other embodiments not set forth herein. Accordingly, the present invention also provides embodiments that include combinations of one or more of the illustrative embodiments described above. Modifications and variations of the present invention as set forth herein may be made without departing from the spirit and scope of the invention, and accordingly, such limitations should be imposed as are indicated by the appended claims.

In the claims hereof, any element expressed as a means for performing a specified function is intended to encompass any way of performing that function. The invention as defined by such claims resides in the fact that: the functionality provided by the various enumerated devices is combined and brought together in the manner as called for by the claims. It is thus regarded that any means that can provide those functionalities are equivalent to those shown herein.

In the appended claims and the foregoing description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It will be appreciated that, if any prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art.

Claims (18)

1. A composition for reducing, suppressing or inhibiting malodor generated from a body part of a subject, the composition comprising:

an effective amount of an active ingredient comprising one or more of hexamine, derivatives thereof, and compounds thereof; and

a buffer system adapted to maintain the pH of the composition in the range of about 7.0 to about 11 when the composition is applied to the body part.

2. The composition of claim 1, wherein the pH range is from about 7.5 to about 10.0.

3. The composition of claim 1, wherein the buffer system comprises one or more of an inorganic compound and an organic compound.

4. The composition of claim 1, wherein the buffer system comprises one or more compounds selected from the group consisting of: 3-morpholinopropane-1-sulfonic acid (MOPS), 4- (2-hydroxyethyl) -1-piperazineethanesulfonic acid) (HEPES), 3- (cyclohexylamino) -1-propanesulfonic acid (CAPS), 3- [ [1, 3-dihydroxy-2- (hydroxymethyl) propan-2-yl ] amino ] -2-hydroxypropane-1-sulfonic acid (TAPSO), 2-amino-2- (hydroxymethyl) -1, 3-propanediol (Trizma), and phosphate ester compounds; salts thereof; and combinations thereof.

5. The composition of claim 1, wherein the buffer system comprises an aqueous buffer solution.

6. The composition of claim 1, wherein the active ingredient comprises about 5 w/v% to about 40 w/v% hexamine relative to the total volume of the composition.

7. The composition of claim 1, further comprising one or more excipients selected from the group consisting of: glycerin, sodium bisulfite, hydrochloric acid and ammonium carbonate.

8. The composition of claim 1, further comprising one or more of an antibacterial agent and an antifungal agent.

9. The composition of claim 8, wherein the antibacterial agent comprises one or more of a disinfectant and a biocide.

10. The composition of claim 1, further comprising a chelating agent.

11. The composition of claim 1, further comprising one or more additives selected from the group consisting of: cosmetic agents, preservatives, thickeners, stabilizers, pH adjusting agents, propellants, solvents, fragrances, coolants, sunscreens.

12. A deodorant formulation for use at a body part of a subject comprising the composition of any one of the preceding claims.

13. The deodorant formulation of claim 12, wherein the formulation is provided in one or more of the following forms: solids, gels, creams, powders, liquids, sprays, and wipes.

14. The deodorant formulation of claim 12, wherein the formulation is to be applied topically.

15. A method of preparing a low skin irritation composition for reducing, suppressing or inhibiting malodor from a body part of a subject, the method comprising:

providing an effective amount of an active ingredient comprising one or more of hexamine, derivatives thereof, and compounds thereof;

providing a buffer system adapted to maintain the pH of the composition in the range of about 7.0 to about 11.0 when the composition is applied to the body part;

wherein the buffer system is adapted to substantially neutralize local acidity of the body part, thereby reducing or minimizing the production of skin irritant by-products from the active ingredient.

16. The method of claim 15, wherein the byproduct comprises one or more aldehydes.

17. The method of claim 15, wherein the byproduct comprises formaldehyde.

18. The method of claim 15, wherein the production of the byproduct is catalyzed by acidic sweat present on the body part.