Patent Publication Number: US-2009227683-A1

Title: Compositions for Providing an Analgesic Effect to the Skin

Description:
FIELD OF THE INVENTION 
     The present invention relates to compositions containing an amine-containing compound and a sensation-blocking agent, which compositions provide an analgesic effect to the skin when applied to an area of skin exhibiting symptoms of itch, pain, stinging, burning sensations, and the like. 
     BACKGROUND OF THE INVENTION 
     Eczema, psoriasis, acne, rosacea, contact irritant dermatitis, atopic dermatitis, allergic dermatitis, sunlight-induced dermatoses and dry skin are all conditions that cause itch, pain, stinging and/or burning sensations of the skin. Consumers have relied on analgesic agents to treat these conditions for many years. Analgesic agents reduce neurosensory sensations, such as pain, itch, sting and burning sensations, without resulting in loss of consciousness. Analgesics are sometimes referred to as painkiller medications. There are many different types of analgesic medications available in both prescription and over-the-counter preparations. Examples of analgesic drugs include aspirin, acetaminophen, ibuprofen, naproxen, the COX-2 inhibitor celecoxib, and narcotic drugs including morphine, oxycodone and hydrocodone. 
     Topical analgesic agents are also called counter-irritants. The name derives from the fact that these agents cause a reddening of the skin by causing the blood vessels of the skin to dilate, which gives a soothing feeling of warmth. The term counter-irritant refers to the idea that irritation of the sensory nerve endings alters or offsets pain in the underlying muscle or joints that are served by the same nerves. Examples of topical analgesic agents include capsaicin, capsicum oleoresin, choline salicylate, ethyl salicylate, glycol salicylate, methyl salicylate, menthol, salicylic acid and turpentine oil. Although analgesic agents are effective in relieving irritation, some have undesirable side effects. For example, some analgesics slow the heart rate of the consumer. Other analgesics are difficult to deliver topically due to skin permeability issues. There is a continuing need for compositions that provide an analgesic effect to the skin without the need for the use of conventional analgesic materials, thereby relieving or reducing itch, pain, stinging and/or burning sensations of the skin while avoiding the need to use conventional analgesic materials. 
     SUMMARY OF THE INVENTION 
     The present invention provides a composition including an amine-containing compound selected from the group consisting of Formula 1 and Formula II 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3 , R 4  and R 5  independently are selected from the group consisting of hydrogen, C 1 -C 6  alkyl and C 1 -C 6  hydroxyalkyl; or a cosmetically-acceptable salt thereof, and a sensation-blocking agent, wherein the amine-containing compound and the sensation-blocking agent are present in amounts effective to provide an analgesic effect to the skin when applied to an area of skin exhibiting symptoms of itch, pain, stinging, burning sensations, and the like, without the presence of conventional analgesic materials. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The compositions of the present invention include an amine-containing compound selected from the group consisting of Formula 1 and Formula II, 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3 , R 4  and R 5  independently are selected from the group consisting of hydrogen, C 1 -C 6  alkyl, and C 1 -C 6  hydroxyalkyl; or a cosmetically-acceptable salt thereof. In one embodiment, the compositions of the present invention contain at least one compound of Formula I where R 1 , R 2 , R 3  and R 4  each are selected from the group consisting of C 1 -C 3  alkyl and C 1 -C 3  alkanol. In a further embodiment, at least one of R 1 , R 2 , R 3  and R 4  of Formula I is a C 2 -C 3  alkanol group bearing at least one hydroxyl group. Examples of compounds of Formula I include, but are not limited to, N,N,N′,N′-Tetrakis(2-hydroxypropyl)ethylenediamine (THPED), N,N,N′,N′-Tetrakis(2-hydroxyethyl)ethylene diamine (THEED), N,N,N′,N′-tetramethylethylene diamine (TEMED), the structures of which are set forth below, enantiomers thereof, or diastereoisomers thereof. 
     
       
         
         
             
             
         
       
     
     Examples of compounds of Formula II include, but are not limited to, Tris[2-(isopropylamino)ethylamine, the structure of which is set forth below, enantiomers thereof, or diastereoisomers thereof. 
     
       
         
         
             
             
         
       
     
     The synthesis of N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine from the reaction of ethylenediamine with propylene oxide is described in U.S. Pat. No. 2,697,118. 
     The amine-containing compounds of the present invention may also be present in the form of cosmetically-acceptable salts. For use in medicine, the salts of the compounds of this invention refer to non-toxic “cosmetically-acceptable salts,” or cosmetically-acceptable acidic/anionic or basic/cationic salts. Cosmetically-acceptable acidic/anionic salts include, but are not limited to, acetate, benzenesulfonate, benzoate, bicarbonate, bitartrate, bromide, calcium edetate, camsylate, carbonate, chloride, citrate, dihydrochloride, edetate, edisylate, estolate, esylate, fumarate, glyceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate, hydrabamine, hydrobromide, hydrochloride, hydroxynaphthoate, iodide, isethionate, lactate, lactobionate, malate, maleate, mandelate, mesylate, methylbromide, methylnitrate, methylsulfate, mucate, napsylate, nitrate, pamoate, pantothenate, phosphate/diphospate, polygalacturonate, salicylate, stearate, subacetate, succinate, sulfate, tannate, tartrate, teoclate, tosylate and triethiodide. Cosmetically-acceptable basic/cationic salts include, but are not limited to, salts of aluminum, benzathine, calcium, chloroprocaine, choline, diethanolamine, ethylenediamine, lithium, magnesium, meglumine, potassium, procaine, sodium and zinc. Other salts may, however, be useful in the preparation of compositions according to the present invention. Organic or inorganic acids also include, but are not limited to, hydriodic, perchloric, sulfuric, phosphoric, propionic, glycolic, methanesulfonic, hydroxyethanesulfonic, oxalic, 2-naphthalenesulfonic, p-toluenesulfonic, cyclohexanesulfamic, saccharinic or trifluoroacetic acid. The amine-containing compound is present in the composition at an amount of from about 0.75% to about 10%, for example 0.75% to 2%, by weight of the composition. 
     The compositions of the present invention also contain a sensation-blocking agent. By sensation-blocking agent, it is meant that such agents, when applied in combination with the amine-containing compound to an area of skin exhibiting at least one symptom of itch, pain, stinging, burning sensations, and the like, provide potassium ion at the symptomatic area of skin to which the composition is administered, so as to provide an analgesic effect, as described herein. The potassium ion may be delivered directly to the area of the skin by topical administration of a composition containing potassium ion therein, or by topical administration of a composition containing a sensation-blocking agent that provides for generation of the potassium ion at the area of skin to which the composition is administered. Such agents may be selected from the group consisting of potassium salts and potassium channel agonists. Potassium salts may be used to deliver potassium ion to the site of the skin exhibiting symptoms, while potassium channel agonists permit potassium ions to be generated at the site of the skin exhibiting symptoms. 
     Compositions of the present invention contain the sensation-blocking agents in amounts effective to provide an analgesic effect to the skin without the requirement of a conventional analgesic material. In determining such analgesic effect to the skin, known methods as set forth in Liebel et al., Arch Dermatol Res. 298:191-199, 2006, were employed. In particular, percent inhibition of scratching and percent inhibition of ear edema were examined as described in the examples herein. Compositions of the present invention are effective in providing at least about 25 percent inhibition of ear edema, or at least about 30 percent. In certain embodiments, the compositions provide greater than about 40 percent inhibition of ear edema. In addition, certain embodiments of the present invention provide greater than about 50 percent, or greater than about 60 percent inhibition of scratching, according to test methods utilized. 
     In the case of potassium salts, the amount of the potassium salt in the compositions of the present invention is effective to provide potassium ion in the composition at a range of from about 0.15% to about 10%, for example from about 0.20% to about 2%, by weight of the composition. Suitable potassium salts include, but are not limited to, potassium lactate, potassium bromide, potassium carbonate, potassium chlorate, potassium chloride, potassium chromate, potassium cyanide, potassium dichromate, potassium iodide, potassium nitrate, potassium sulfate, potassium pyrophosphate, potassium fluorosilicate and potassium sodium tartrate. 
     Suitable potassium channel agonist include, without limitation, a chemically diverse group of agents such as minoxidil, pinacidil, diazoxide, cromakalin, nicorandil, and aprikalim. (See Lawson., 2000; Takano et. al., 2004, and those listed in table 4.3 of Biochemical Targets of Plant Bioactive Compounds, Polya., 2003). Compositions of the present invention may comprise from about 0.25% to about 10% percent by weight of the potassium channel agonist, or from about 0.25% to about 2% by weight of the composition. While not intending to be limited by the following, potassium channel agonists induce an efflux of potassium from the cells. This creates a hyperpolarized state that restricts calcium from entering back into the cells and dampens cellular excitability. Potassium channel agonists also affect neurons by decreasing neuronal excitability and interfering with neurotransmission. Itch, pain, sting and burning sensations are transmitted by sensory neurons such as unmyelinated C-fibers. Thus, the effects of potassium channel agonists on neurotransmission inhibit these neurosensory sensations. 
     The compositions of the present invention are prepared by standard techniques well known to those skilled in the art. If the composition comprises more than one phase, in general the different phases will be prepared separately, with materials of similar phase partitioning being added in any order. The two phases will then be combined with vigorous stirring to form the multiphase system, e.g., an emulsion or dispersion. Any ingredients in the formulation with high volatility, or which are susceptible to hydrolysis at high temperatures, will usually be added post-mixing of the different phases with gentle stirring. 
     The compositions of the present invention are useful for relieving or reducing symptoms of itch, pain, stinging and/or burning sensations of the skin by providing an analgesic effect. By analgesic effect, it is meant that the composition, when applied to an area of skin suffering from at least one symptom of itch, pain, stinging or burning sensations, provides relief or reduction of such symptoms that are similar to relief or reduction of such symptoms provided by known analgesic compositions, but without the negative side affects of such known analgesic compositions. Depending on the sensation-blocking agent utilized in the compositions of the present invention, the weight ratio of amine-containing compound to sensation-blocking agent may range from about 1:1 to about 1:3, e.g. about 1:2. 
     The compositions are topically applied to skin exhibiting these symptoms. As used herein, “topically applying” means directly laying on or spreading on outer skin, e.g., by use of the hands or an applicator such as a wipe, puff, roller or spray. As used herein, “cosmetically-acceptable” means that the product(s), compound(s), or composition(s) which the term describes are suitable for use in contact with tissue of a mammal (e.g., the skin or hair) without undue toxicity, incompatibility, instability, irritation, allergic response, and the like. This term is not intended to limit the compound/product/composition to which it describes for use solely as a cosmetic, e.g., the ingredient/product may be used as a pharmaceutical. As used herein, “topical carrier” means one or more compatible solid or liquid filler diluents that are suitable for topical administration to a mammal. Examples of topical carriers include, but are not limited to, water, waxes, oils, emollients, emulsifiers, thickening agents, gelling agents, and mixtures thereof. 
     The compositions of the present invention may be provided as formulations suitable for topical application to skin. The composition may comprise a cosmetically-acceptable topical carrier. The cosmetically-acceptable topical carrier may comprise from about 50% to about 99.99%, by weight, of the composition, e.g., from about 80% to about 95%, by weight, of the composition. The compositions may be made into a wide variety of product types that include, but are not limited to, solid and liquid compositions, such as lotions, creams, gels, sticks, sprays, shaving creams, ointments, cleansing liquid washes and solid bars, shampoos, pastes, powders, mousses, shaving creams and wipes. These product types may comprise several types of cosmetically acceptable topical carriers including, but not limited to, solutions, emulsions, e.g., microemulsions and nanoemulsions, gels, solids and liposomes. The following are non-limitative examples of such carriers. Other carriers can be formulated by those of ordinary skill in the art. 
     The compositions of the present invention can be formulated as solutions. Solutions typically include an aqueous solvent, e.g., from about 50% to about 99.99%, or from about 90% to about 99%, of a cosmetically-acceptable aqueous solvent. Topical compositions of the subject invention may be formulated as a solution comprising an emollient. Such compositions preferably contain from about 2% to about 50% of an emollient(s). As used herein, “emollients” refer to materials used for the prevention or relief of dryness, as well as for the protection of the skin. A wide variety of suitable emollients are known and may be used herein. See International Cosmetic Ingredient Dictionary and Handbook, eds. Wenninger and McEwen, pp. 1656-61, 1626, and 1654-55 (The Cosmetic, Toiletry, and Fragrance Assoc., Washington, D.C., 7 th  Edition, 1997) (hereinafter “INCI Handbook”). 
     A lotion can be made from such a solution. Lotions typically comprise from about 1% to about 20%, e.g., from about 5% to about 10%, of an emollient(s) and from about 50% to about 90%, e.g., from about 60% to about 80%, of water. 
     Another type of product that may be formulated from a solution is a cream. A cream typically comprises from about 5% to about 50%, e.g., from about 10% to about 20%, of an emollient(s) and from about 45% to about 85%, e.g., from about 50% to about 75%, of water. 
     Yet another type of product that may be formulated from a solution is an ointment. An ointment may comprise a simple base of animal or vegetable oils or semi-solid hydrocarbons. An ointment may comprise from about 2% to about 10% of an emollient(s) plus from about 0.1% to about 2% of a thickening agent(s). A more complete disclosure of thickening agents or viscosity increasing agents useful herein can be found in the INCI Handbook pp. 1693-1697. 
     The compositions of the present invention may be formulated as emulsions. If the carrier is an emulsion, from about 1% to about 10%, e.g., from about 2% to about 5%, of the carrier comprises an emulsifier(s). Emulsifiers may be nonionic, anionic or cationic. Suitable emulsifiers are disclosed in, for example, INCI Handbook, pp. 1673-1686. 
     Lotions and creams can be formulated as emulsions. Typically such lotions comprise from 0.5% to about 5% of an emulsifier(s). Such creams would typically comprise from about 1% to about 20%, e.g., from about 5% to about 10% of an emollient(s); from about 20% to about 80%, e.g., from 30% to about 70%, of water; and from about 1% to about 10%, e.g., from about 2% to about 5%, of an emulsifier(s). 
     Single emulsion skin care preparations of the oil-in-water type and water-in-oil type, such as lotions and creams, are well-known in the cosmetic art and are useful in the subject invention. Multiphase emulsion compositions, such as the water-in-oil-in-water type are also useful in the subject invention. In general, such single or multiphase emulsions contain water, emollients, and emulsifiers as essential ingredients. 
     The compositions of this invention can also be formulated as a gel, e.g., an aqueous gel using a suitable gelling agent(s). Suitable gelling agents for aqueous gels include, but are not limited to, natural gums, acrylic acid and acrylate polymers and copolymers, and cellulose derivatives, e.g., hydroxymethyl cellulose and hydroxypropyl cellulose. Suitable gelling agents for oils such as mineral oil include, but are not limited to, hydrogenated butylene/ethylene/styrene copolymer and hydrogenated ethylene/propylene/styrene copolymer. Such gels typically comprise between about 0.1% and 5%, by weight, of such gelling agents. 
     The compositions of the present invention can also be formulated into a solid formulation, e.g., a wax-based stick, soap bar composition, powder, or a wipe containing powder. 
     The compositions of the invention may contain, in addition to the aforementioned components, a wide variety of additional oil-soluble materials and/or water-soluble materials conventionally used in compositions for use on skin, hair, and nails at their art-established levels. 
     The compositions may be applied one or more times a day, for example twice a day. The amount used will vary with the age and physical condition of the end user, the duration of the treatment, the specific compound, product, or composition employed, the particular cosmetically-acceptable carrier utilized, and like factors. Several examples are described below. The invention should not be construed to be limited to the details thereof. 
     EXAMPLE 1 
     Scratching Against Compound 48/80 
     Albino male CD-1 mice, 7-9 weeks old, were used. Testing was based on known methods (See Liebel et al., Arch Dermatol Res. 298:191-199, 2006.) Test agents were prepared at concentrations noted in Table 1 in 100% ethanol and 50 μL was applied topically to the shaved dorsal skin 30 minutes prior to induction of scratching (8 mice per treatment group). Compound 48/80 (50 μg/50 μL: w/v) was then injected inter-dermal to the dorsal area and scratches were then counted for 30 minutes. The results are shown in Table 1. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Topical Dose, 
                 % Inhibition of 
               
               
                 Treatment 
                 as % w/v 
                 Scratching* 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Tetrahydroxypropyl 
                 1 
                 9.39 
               
               
                 ethylenediamine 
               
               
                 Potassium Ion (delivered 
                 0.206 
                 −8.84 
               
               
                 as 1% Potassium Lactate) 
               
               
                 Potassium Ion (delivered 
                 0.206 + 1 
                 61.18 
               
               
                 as 1% Potassium 
               
               
                 Lactate) + Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                   
               
               
                 % Inhibition = ((Untreated Group Number of Scratches − Treatment Group 
               
               
                 Number of Scratches)/Untreated Group Number of Scratches) × 100 
               
            
           
         
       
     
     The combination of potassium lactate and tetrahydroxypropyl ethylenediamine was highly effective in this model. In comparison, equal levels of potassium ion or tetrahydroxypropyl ethylenediamine alone exhibited very weak to no inhibition. These results demonstrate that the combination of appropriate amounts of potassium ion, as delivered by potassium lactate, and tetrahydroxypropyl ethylenediamine synergistically produced an analgesic effect in reducing scratching, and would therefore be expected to prevent and/or treat itch, pain, sting and/or burning sensations. 
     EXAMPLE 2 
     Neurosensory inflammation, also referred to as neurogenic inflammation, is a type of inflammation triggered by sensory nerve activation in skin. Certain natural substances that act on vanilloid receptors cause sensory nerves (C-fibers) to release inflammatory neuropeptides. In mouse skin, an edema response occurs rapidly upon application of a vanilloid receptor activator, such as capsaicin or resiniferatoxin (RTX). Compounds that inhibit the response to neurosensory stimulation could be useful as topical analgesics, itch or sting inhibitors or soothing agents for irritated skin. 
     Albino male CD-1 mice, 7-9 weeks old, were used. Induction of neurogenic inflammation in the mouse ear was based on known methods (See Liebel et al., Arch Dermatol Res. 298:191-199, 2006.). A 20-μL volume of Resiniferatoxin (0.05%) prepared in acetone was applied to the left ears (7 mice per treatment group). The right ear was not treated. Test agents were prepared in a 70% ethanol/30% propylene glycol vehicle and applied to the left ear (20 μL) immediately after resiniferatoxin challenge. The percent inhibition was calculated by comparing treatments to resiniferatoxin alone. Anti-neurogenic inflammation effects of compounds are evident as an inhibition of the increase in ear weight. The results are shown in Table 2. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Topical Dose, 
                 % Inhibition of the 
               
               
                 Treatment 
                 as % w/v 
                 Ear Edema* 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Lidocaine 
                 0.5 
                 28.7 
               
               
                 Tetrahydroxypropyl 
                 1 
                 4.04 
               
               
                 ethylenediamine 
               
               
                 Tris[2-(isopropylamino) 
                 0.5 
                 13.62 
               
               
                 ethylamine 
               
               
                 Potassium Ion (delivered 
                 0.206 
                 13.52 
               
               
                 as 1% Potassium Lactate) 
               
               
                 Potassium Ion (delivered 
                 0.206 + 1   
                 43.83 
               
               
                 as 1% Potassium Lactate) + 
               
               
                 Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Potassium Ion (delivered 
                 0.206 + 0.5 
                 48.83 
               
               
                 as 1% Potassium Lactate) + 
               
               
                 Tris[2- 
               
               
                 (isopropylamino) 
               
               
                 ethyl]amine 
               
               
                   
               
               
                 *% Inhibition = ((Untreated Biopsy Weight − Treatment Biopsy Weight)/Untreated Biopsy Weight) × 100 
               
            
           
         
       
     
     The use of potassium lactate, or tetrahydroxypropyl ethylenediamine or Tris[2-(isopropylamino)ethyl]amine, each one by itself, failed to significantly inhibit the neurogenic inflammatory response to resiniferatoxin. However, the combination of potassium lactate and tetrahydroxypropyl ethylenediamine or Tris[2-(isopropylamino)ethyl]amine significantly inhibited the neurogenic inflammatory response to resiniferatoxin. The combination of potassium lactate and tetrahydroxypropyl ethylenediamine or Tris[2-(isopropylamino)ethyl]amine was highly effective in this model. In comparison, while lidocaine, a known anesthetic compound (Morgan M and Russell W J. Br J Anaesth. 1975 47:586-591, 1975), was also active, the combination of the present invention was significantly more effective than 0.5% lidocaine alone. Together these results demonstrate that the combination of potassium ion, as delivered by potassium lactate in the specific example, and tetrahydroxypropyl ethylenediamine or Tris[2-(isopropylamino)ethyl]amine produced an analgesic effect in reducing neurogenic inflammation, and would therefore be expected to prevent and/or treat itch, pain, sting and/or burning sensations. 
     EXAMPLE 3 
     Different ions of chloride were evaluated in the resiniferatoxin neurogenic inflammation model in mice as described in Example 2. The results are shown in Table 3. 
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 % Inhibition  
               
               
                   
                 Topical Dose, 
                 of the 
               
               
                 Treatment 
                 as % w/v 
                 Ear Edema* 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Potassium Ion (delivered 
                 0.524 
                 9.98 
               
               
                 as 1% Potassium 
               
               
                 Chloride) 
               
               
                 Potassium Ion (delivered 
                 0.524 + 1    
                 45.89 
               
               
                 as 1% Potassium 
               
               
                 Chloride) + Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Sodium Chloride 
                 1 
                 7.06 
               
               
                 Sodium Chloride + Tetrahydroxypropyl 
                 1 + 1 
                 6.01 
               
               
                 ethylenediamine 
               
               
                 Calcium Chloride 
                 1 
                 −3.24 
               
               
                 Calcium Chloride + Tetrahydroxypropyl 
                 1 + 1 
                 15.17 
               
               
                 ethylenediamine 
               
               
                   
               
               
                 *% Inhibition = ((Untreated Biopsy Weight − Treatment Biopsy Weight)/Untreated Biopsy Weight) × 100 
               
            
           
         
       
     
     The combination of potassium chloride and tetrahydroxypropyl ethylenediamine was highly effective in this model. In comparison, sodium chloride and calcium chloride in combination with tetrahydroxypropyl ethylenediamine exhibited very weak inhibition of the neurogenic inflammation. 
     EXAMPLE 4 
     Different potassium salts were studied in the Resiniferatoxin neurogenic inflammation model in mice as described in Example 2. The results are shown in Table 4. 
     
       
         
           
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                 % Inhibition 
               
               
                   
                 Topical Dose, 
                 of the 
               
               
                 Treatment 
                 as % w/v 
                 Ear Edema* 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Potassium Ion (delivered 
                 0.398 
                 −2.89 
               
               
                 as 1% Potassium Acetate) 
               
               
                 Potassium Ion (delivered 
                 0.398 + 1 
                 33.30 
               
               
                 as 1% Potassium Acetate) + 
               
               
                 Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Potassium Ion (delivered 
                 0.283 
                 4.52 
               
               
                 as 1% Potassium 
               
               
                 Carbonate) 
               
               
                 Potassium Carbonate + 
                 0.283 + 1 
                 33.55 
               
               
                 Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Potassium Ion (delivered 
                 0.524 
                 9.98 
               
               
                 as 1% Potassium 
               
               
                 Chloride) 
               
               
                 Potassium Ion (delivered 
                 0.524 + 1 
                 45.89 
               
               
                 as 1% Potassium 
               
               
                 Chloride) + Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Potassium Lactate 
                 0.206 
                 13.52 
               
               
                 Potassium Lactate + Tetrahydroxypropyl 
                 0.206 + 1 
                 43.83 
               
               
                 ethylenediamine 
               
               
                   
               
               
                 *% Inhibition = ((Untreated Biopsy Weight − Treatment Biopsy Weight)/Untreated Biopsy Weight) × 100 
               
            
           
         
       
     
     The combination of tetrahydroxypropyl ethylenediamine with any of the potassium salts tested provided an inhibition against induced neurogenic inflammation. The potassium salts alone had very weak to no activity against the neurogenic inflammation. Together, these results demonstrate that various potassium salts in combination with tetrahydroxypropyl ethylenediamine produced an analgesic effect in reducing neurogenic inflammation, and would therefore be expected to prevent and/or treat itch, pain, sting and/or burning sensations. 
     EXAMPLE 5 
     A topical formulation containing potassium lactate and tetrahydroxypropyl ethylenediamine was created for testing following the ingredient list of Table 5. 
     
       
         
           
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Ingredient Trade Name 
                 Formula % Weight 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Purified Water 
                 68.5 
               
               
                 EleFac I-205 
                 6 
               
               
                 DMS Concentrate Probiol N03031 (Kuhs Gmbh) 
                 3.8 
               
               
                 Glycerin 
                 3 
               
               
                 DC 9566 Silicone Elastomer 
                 3 
               
               
                 Hexylene Glycol 
                 2.5 
               
               
                 D-Panthenol, USP 
                 2 
               
               
                 Oliwax 
                 2 
               
               
                 Betafin BP-20 
                 1.5 
               
               
                 Advanced Moisture Complex 
                 1.5 
               
               
                 PURASAL HiPure P (Potassium Lactate) 
                 1 
               
               
                 DC 200 Fluid 50 cst 
                 1 
               
               
                 Crodacol C-95 
                 1 
               
               
                 Tetrahydroxypropyl ethylenediamine (Neutrol TE) 
                 1 
               
               
                 Carbopol Ultrez 10 
                 0.75 
               
               
                 Sodium Hydroxide, 20% 
                 0.7 
               
               
                 Nipagin M 
                 0.3 
               
               
                 Versene NA 
                 0.2 
               
               
                 Keltrol 1000 
                 0.15 
               
               
                 Nipasol M 
                 0.1 
               
               
                   
                 100 
               
               
                   
               
            
           
         
       
     
     EXAMPLE 6 
     The formulation prepared in Example 5 was tested in the Resiniferatoxin neurogenic inflammation model in mice as described in Example 2. The results are shown in Table 6. 
     
       
         
           
               
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                   
                 Topical Dose, 
                 % Inhibition of the 
               
               
                 Treatment 
                 as % w/v 
                 Ear Edema* 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Placebo Formulation 
                 0 
                 1.22 
               
               
                 Potassium Ion (delivered 
                 0.206 + 1 
                 30.18 
               
               
                 as 1% Potassium Lactate) + 
               
               
                 Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Formulation 
               
               
                   
               
               
                 *% Inhibition = ((Untreated Biopsy Weight − Treatment Biopsy Weight)/Untreated Biopsy Weight) × 100 
               
            
           
         
       
     
     These results demonstrate that potassium lactate in combination with tetrahydroxypropyl ethylenediamine produced an analgesic effect in reducing neurogenic inflammation, and would therefore be expected to prevent and/or treat itch, pain, sting and/or burning sensations. 
     EXAMPLE 7 
     A blinded controlled clinical usage trial to evaluate the tolerance and efficacy of a formulation containing potassium lactate and tetrahydroxypropyl ethylenediamine was used on 30 healthy adult human subjects having mild to moderate atopic dermatitis as determined by the Hanifin and Rajka criteria. The subjects also suffered from itch associated with their atopic dermatitis. A clinical and subject self-assessment of the itch sensation was taken at baseline, one hour after application and 24 hours after a single application. The results are shown in Table 7. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 7 
               
               
                   
               
               
                   
                   
                 Clinical 
                 Self- 
               
               
                   
                   
                 Assessment 
                 Assessment 
               
               
                 Treatment 
                 Time Point* 
                 Score** 
                 Score*** 
               
               
                   
               
             
            
               
                 Potassium Ion (delivered 
                 Baseline 
                 1.94 
                 3.75 
               
               
                 as 1% Potassium Lactate) + 
               
               
                 Tetrahydroxypropyl 
               
               
                 ethylenediamine 
               
               
                 Formulation 
               
               
                   
                  1 hour after 
                 0.00 
                 — 
               
               
                   
                 24 hours after 
                 0.39 
                 6.18 
               
               
                   
               
               
                 *time after a single application of the formulation 
               
               
                 **(0 = No itch, 1 = Mild itch, 2 = Moderate itch, 3 = Severe Itch) 
               
               
                 ***(10 point scale 1 = very itchy, 10 = does not itch at all) 
               
            
           
         
       
     
     A single application of a formulation containing potassium lactate and tetrahydroxypropyl ethylenediamine was able to deliver a prolonged reduction in the itch sensation in subjects with itchy skin due to atopic dermatitis. These results demonstrate that potassium lactate and tetrahydroxypropyl ethylenediamine produced an analgesic effect in reducing itch, and would therefore be expected to prevent and/or treat itch, pain, sting and/or burning sensations. 
     EXAMPLE 8 
     Potassium Channel Agonists Against Scratching by Compound 48/80 
     Albino male CD-1 mice, 7-9 weeks old, were used. Testing was based on known methods (See Liebel et al., Arch Dermatol Res. 298:191-199, 2006.) Test agents were prepared in 100% ethanol and 50 uL was applied topically to the shaved dorsal skin 30 minutes prior to induction of scratching (8 mice per treatment group). Compound 48/80 (50 ug/50 uL w/v) was then injected inter-dermal to the dorsal area and scratches were then counted for 30 minutes. 
     
       
         
           
               
               
               
             
               
                 TABLE 8 
               
               
                   
               
               
                   
                 Topical Dose, 
                 % Inhibition of 
               
               
                 Treatment 
                 as % w/v 
                 Scratching* 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Tetrahydroxypropyl 
                 1 
                 9.39 
               
               
                 ethylenediamine 
               
               
                 Minoxidil 
                 1 
                 8.42 
               
               
                 Minoxidil + Tetrahydroxypropyl 
                 1 + 1 
                 51.74 
               
               
                 ethylenediamine 
               
               
                 Minoxidil + Tetrahydroxypropyl 
                 0.5 + 1   
                 46.05 
               
               
                 ethylenediamine 
               
               
                 Minoxidil + Tetrahydroxypropyl 
                 0.25 + 1   
                 1.80 
               
               
                 ethylenediamine 
               
               
                 Pinacidil 
                 1 
                 17.03 
               
               
                 Pinacidil + Tetrahydroxypropyl 
                 1 + 1 
                 80.44 
               
               
                 ethylenediamine 
               
               
                 Pinacidil + Tetrahydroxypropyl 
                 0.25 + 1   
                 28.53 
               
               
                 ethylenediamine 
               
               
                   
               
               
                 *% Inhibition = ((Untreated Group Number of Scratches − Treatment Group 
               
               
                 Number of Scratches)/Untreated Group Number of Scratches) × 100 
               
            
           
         
       
     
     These results demonstrate that potassium channel agonists in combination with tetrahydroxypropyl ethylenediamine produced a synergistic analgesic effect in reducing scratching, and would therefore be expected to prevent and/or treat itch, pain, sting and/or burning sensations.