Dicarboxylic acid concentrate

Abstract

A substantially anhydrous dermatological concentrate comprising (a) a long-chain alkyldicarboxylic acid having 6 to 12 carbon atoms and low solubility in water, selected from the group consisting of adipic acid, azelaic acid, sebacic acid, and dodecanediic acid; and (b) an amidoamine. The substantially anhydrous dermatological concentrate may contain salicylic acid.

Description

Background Art

[0001] Background of the Invention Azelaic acid is a dicarboxylic acid found in whole grains such as wheat, rye, and barley, and is produced by Malassezia furfur, a commensal yeast that is part of the human skin microbiome.

[0002] Azelaic acid has been reported in the scientific literature to exhibit antibacterial, keratolytic, acne-improving, and antioxidant effects. It inhibits protein synthesis in microbial cells and reduces the thickness of the stratum corneum.

[0003] For the treatment of acne vulgaris and inflammatory papules and pustules of mild to moderate rosacea, two dosage forms with different prescription strengths are available, namely a cream with 20% active ingredient (AZELEX®) and a gel or foam with 15% active ingredient (FINACEA®). A low-concentration "over-the-counter" formulation with 10% active ingredient is sold with a cosmetic indication as a brightener that improves dullness, color unevenness, and skin texture roughness.

[0004] Other reported dermatological benefits of using azelaic acid include suppression of sebum production in sebaceous glands and reduction of hair loss or thinning hair, such as by functioning as a competitive inhibitor of the reduction of testosterone to dihydrotestosterone.

[0005] Representative over-the-counter skin care products containing azelaic acid are THE ORDINARY® 10% Azelaic Acid Suspension and PAULA’S CHOICE® 10% Azelaic Acid Booster (also containing 0.5% salicylic acid).

[0006] U.S. Patent No. 6,734,210 (expired) describes the difficulty in solubilizing azelaic acid. Water only "slightly dissolves" azelaic acid to a maximum of 0.24% by weight (w / w), a concentration that is "unlikely" to be clinically effective. Isopropanol is considered a "good" solvent, but is deemed "unsatisfactory" because it can cause drying. Ethanol destabilizes azelaic acid at "room temperature," resulting in a "completely ineffective composition."

[0007] U.S. Patents 4,713,394 and 4,885,282 similarly characterize the instability of azelaic acid when dissolved in ethyl alcohol.

[0008] In July 2020, Azeco Cosmeceuticals published a "Technical Information File" providing guidelines for formulations using azelaic acid and a general solution to the limited solubility of azelaic acid in aqueous systems (i.e., incorporating azelaic acid into the final formulation using a "pre-mixture"). According to Azeco, the "simplest" "pre-mixture" is formed by dissolving azelaic acid in ethanol or isopropanol. However, Azeco notes that since these alcohols are undesirable in many dermatological formulations, diols, namely propanediol (e.g., available as Zemea® from DuPont Tate & Lyle Bio Products Company, LLC, Wilimington, Delaware), 1,3-butylene glycol, and pentylene glycol (e.g., available as Pentiol Green+ from Minasolve SAS, Beuvry-La-Foret, France), are used instead. Azeco's formulation guidelines also comment that "glycerin and glycerin / water mixtures are suitable solvent systems; [however] the maximum concentration of water in this solvent mixture is not adequately specified and has not been reported in the literature." [Overview of the project] [Problems that the invention aims to solve]

[0009] There has been a continuous demand for concentrates of azelaic acid (and other long-chain alkyl dicarboxylic acids with 6 to 12 carbon atoms that have low solubility in water) that can be incorporated into topical formulations containing a hydrophilic carrier (water, or a combination of water and a water-miscible component (e.g., water / glycol or water / alcohol mixture), or a mixture of alcohols and / or glycols) without forming visible precipitates.

[0010] Concentrates containing both azelaic acid (or other long-chain alkyldicarboxylic acids with 6 to 12 carbon atoms that have low water solubility) and salicylic acid have been continuously in demand to date. These needs are met by the substantially anhydrous dermatological concentrate disclosed in this invention. [Means for solving the problem]

[0011] Summary of the Invention A first aspect of the disclosure of the present invention is a substantially anhydrous dermatological concentrate, (a) A long-chain alkyldicarboxylic acid, preferably azelaic acid, selected from the group consisting of adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid, which has low solubility in water and has 6 to 12 carbon atoms; (b) an amidoamine, preferably an alkylamidoalkylamine, more preferably a fatty acid amidopropyldimethylamine, most preferably cocamidopropyldimethylamine; This relates to substantially anhydrous dermatological concentrates that essentially consist of (or comprise) of.

[0012] A second aspect of the disclosure of the present invention further relates to a substantially anhydrous dermatological concentrate consisting of and derived from a substantially anhydrous dermatological concentrate according to the first aspect of the present disclosure of the present invention, which consists of (or comprises) salicylic acid.

[0013] When a substantially anhydrous dermatological concentrate according to the first or second aspect of the disclosure of the present invention is added to a hydrophilic carrier (e.g., water), neither the long-chain alkyl dicarboxylic acid nor / or salicylic acid produces any visible precipitate. [Brief explanation of the drawing]

[0014] Brief explanation of the drawing [Figure 1] The following shows comparative results of enzyme-linked immunosorbent assay (ELISA) for tumor necrosis factor α (TNF-α) after application of the substantially anhydrous dermatological concentrate of the present invention. [Figure 2] The following shows comparative results of enzyme-linked immunosorbent assay (ELISA) for tumor necrosis factor α (TNF-α) after application of the substantially anhydrous dermatological concentrate of the present invention. [Figure 3] The following shows comparative ELISA results for caspase-1 (CASP-1) after application of the substantially anhydrous dermatological concentrate of the present invention. [Modes for carrying out the invention]

[0015] Detailed description of the invention In the disclosure of this invention, "low solubility in water" means less than 30 g / L in water at 25°C. See Fiume, MM et al, “Final Report of the Cosmetic Ingredient Review Expert Panel on the Safety Assessment of Dicarboxylic Acids, Salts, and Esters” International Journal of Toxicology 31(Supplement 1)5S-76S(2012)(DOI:10.1177 / 1091581812447203).

[0016] In the description of the concentrate of the disclosure of the present invention, "substantially anhydrous" is understood to mean that no water other than the water of hydration contained in the components of the substantially anhydrous dermatological concentrate of the disclosure of the present invention is added to the concentrate. Typically, the water content of the concentrate is less than 1.0% by weight, preferably less than 0.5% by weight, and more preferably less than 0.1% by weight.

[0017] The term "dermatological" is understood to be suitable for topical application to the skin, hair, or scalp of mammals.

[0018] The first essential component of the substantially anhydrous dermatological concentrate of the disclosure of the present invention is a dicarboxylic acid with low solubility in water. These acids are straight-chain alkyl chains with functionalized ends, where the carboxylic acid functional groups are separated by 4 to 10 carbon atoms.

[0019] Preferred dicarboxylic acids with low solubility in water, suitable for inclusion in the substantially anhydrous dermatological concentrate of the present invention, are selected from the following: Adipic acid: HOOC(CH2)4COOH, with a 4-carbon atom spacing. Azelaic acid: HOOC(CH2)7COOH, with a 7-carbon atom spacing. Sebacic acid: HOOC(CH2)8COOH, with an 8-carbon atom spacing. Dodecanedioic acid: HOOC(CH2) 10 COOH, with a 10-carbon atom spacing.

[0020] The second essential component of the substantially anhydrous dermatological concentrate of the disclosure of the present invention is an amidoamine, preferably fatty acid amide propyldimethylamine, which is generally produced by amidating a fatty acid with 3,3-dimethylaminopropylamine (DMAPA) under alkaline or acidic conditions in the presence of a catalyst. The resulting component has a similar fatty acid amide core structure and two major functional groups separated by a propyl chain, namely a secondary amide and a tertiary amine.

[0021] A first group of preferred fatty acid amidopropyldimethylamines suitable for inclusion in the substantially anhydrous dermatological concentrate of the present invention includes DMAPA and Prunus Dulcis (almond) oil; Persea Gratissima (avocado) oil; Orbignya Oleifera (babassu) oil; Brassica Campestris (rapeseed) seed oil; Cocos Nucifera (coconut) oil; Avena Sativa (oat) kernel oil; Olea Europaea (olive) oil; Sesamum Indicum (sesame) oil; Glycine Soja (soybean) oil; Helianthus Annus (soybean) oil. It is produced by the reaction of Annuus (sunflower) seed oil; Triticum vulgare (wheat) germ oil; or fatty acids derived from animal fat.

[0022] A second group of fatty acid amidopropyldimethylamines suitable for inclusion in substantially anhydrous dermatological concentrates of the present invention can be produced by the reaction of DMAPA with behenic acid, isostearic acid, lauric acid, linoleic acid, myristic acid, oleic acid, palmitic acid, ricinoleic acid, and stearic acid.

[0023] Another fatty acid amidopropyldimethylamine suitable for inclusion in the substantially anhydrous dermatological concentrate of the present invention includes a condensation product of dilinoleic acid and aminopropyldimethylamine.

[0024] Tallamidopropyldimethylamine, a substituted amine produced by the reaction of DMAPA with fatty acids derived from tall oil, can also be used in the substantially anhydrous dermatological concentrate of the present invention.

[0025] The pH of a topical product produced by adding a substantially anhydrous dermatological concentrate according to the first aspect of the present invention may be alkaline (preferably less than 9), preferably less than 7, and more preferably less than 5.

[0026] The pH of the topical product produced by adding a substantially anhydrous dermatological concentrate according to a second aspect disclosed in the present invention is less than 6, preferably less than 5.

[0027] The substantially anhydrous dermatological concentrates of the present invention may include one or more “functional” or “active” ingredients in concentrations that provide one or more skin benefits, namely, therapeutic agents for inflammatory skin conditions including acne, psoriasis, or rosacea; antibacterial and antifungal agents; antipruritic agents; topical anesthetics; emollients and sedatives; nonsteroidal anti-inflammatory agents; hydrating and moisturizing agents including hyaluronic acid and its derivatives; ingredients that reduce transepidermal water loss and / or improve skin barrier function; antioxidants and agents that reduce the appearance of fine lines and wrinkles, including vitamins, proteins, and peptides; skin bleaching and whitening agents; and plant-derived ingredients including extracts and oils. The amount of these ingredients used may be at least 0.01%, at least 0.1%, at least 0.5%, or at least 1.0% on a weight / weight basis based on the weight of the concentrate.

[0028] Preferred but non-limiting examples of "functional" or "active" ingredients include jojoba seed oils, waxes, esters (including hydrolyzed esters), and mixtures thereof, which are marketed by Vantage Specialty Ingredients, Inc. (Vantage Specialty Ingredients, Inc. Warren, NJ “(Vantage)” under the trademark names LIPONATE® Jojoba NATFILM®).

[0029] The surfactants that can be added to the substantially anhydrous dermatological concentrates disclosed in this invention may be cationic, anionic, nonionic, or amphoteric. Non-limiting examples of surfactants include sodium cocoyl methyl taurate (METAUPON® KMT); magnesium cocoyl methyl taurate; sodium oleoyl methyl taurate (METAUPON® OMT); cocamidopropyl betaine; sodium isethionate (METAUPON® SI); sodium cocoyl isethionate; sodium lauroyl sarcosinate; sodium cocoyl glycine; disodium cocoyl glutamate; disodium laureth sulfosuccinate; and cocamidopropyl hydroxysultaine. METAUPON® surfactants are available from Vantage.

[0030] In certain preferred embodiments, two or more surfactants (surfactant blends) are combined with a hydrophilic carrier and a substantially anhydrous dermatological concentrate of the disclosure of the present invention in the form of, for example, an emulsion or thickening gel (aqueous, water / glycol, or water / alcoholic) or a facial foam, body wash, or shampoo. Preferably, the main surfactant is a taurine salt, preferably Metaupon® KMT or OMT.

[0031] Sodium cocoyl methyl taurate is preferably present at a concentration of about 6% to about 10%, preferably at least about 7.5%, and more preferably at least about 9%, based on the active ingredient.

[0032] Sodium oleoylmethyl taurate is preferably present in the cleaning composition at a concentration of about 1% to about 4%, preferably at least 2%, based on the active ingredient.

[0033] Non-exclusive examples of auxiliary surfactants include cocamidopropyl betaine; sodium cocoyl isethionate; sodium lauroyl sarcosinate; sodium cocoyl glycine; disodium cocoyl glutamate; disodium laureth sulfosuccinate; and cocamidopropyl hydroxysultaine.

[0034] Certain embodiments include a multifunctional jojoba-derived functional enhancer that provides a film-forming agent, preferably a softening, moisturizing, supple, and conditioning effect, which essentially consists of, or comprises, (i) about 75 to about 85 parts hydrolyzed jojoba ester (formed by reacting jojoba oil with alkali metal hydroxide in water), (ii) about 8 to about 15 parts jojoba ester, and (iii) about 7 to about 10 parts water. This is commercially available from Vantage under the trademark name LIPONATE® Jojoba NATFILM®.

[0035] The multifunctional jojoba-derived functional property enhancer is preferably present in a concentration of about 0.1% to about 5% by weight, preferably about 0.5% to about 3% by weight, based on the total weight of the finished formulation.

[0036] Examples of emulsifiers that can be added to specific embodiments include, but are not limited to, oil-in-water emulsifiers (e.g., ceteareth-20); silicone-in-water emulsifiers (e.g., PEG-12 dimethicone); water-in-oil emulsifiers (e.g., polyglyceryl-4 oleate); and water-in-silicone emulsifiers (e.g., PEG / PPG-30 / 10 dimethicone or lauryl PEG / PPG-18 / 18 methicone).

[0037] As will be understood by those skilled in the art, the viscosity of the finished formulation can be adjusted by the selection of a thickening agent, also known in the art as a rheological modifier. Preferred but non-limiting examples of thickening agents suitable for inclusion in the formulations of substantially anhydrous dermatological concentrates of the present invention include gums, pegylated alkyl glycerides, pegylated fatty acid esters, fatty alcohols (preferably those having fatty chains of 16 or more carbon atoms), and ethoxylated fatty alcohols. [Examples]

[0038] Examples The following examples illustrate formulations prepared using the concentrate of the present invention, which contains up to 44% azelaic acid by active ingredient. It will be apparent to those skilled in the art that modifications can be made without departing from the spirit and scope of the present invention, and such modifications can be easily made. The appended claims are not limited to these examples.

[0039] [Table 1]

[0040] Procedure for Example 1 1. In the main container, the components of phase A are mixed by medium-speed propeller mixing without heating. 2. Add the components of phase B and mix until completely dispersed. 3. Add the components of phase C one by one and mix until uniform. 4. Adjust the pH to 5.00 using the components of phase D.

[0041] [Table 2]

[0042] Procedure for Example 2 1. Mix the components of Phase A until hydrated. 2. Mix the components of phase B beforehand. 3. Heat phases A and B to 70-75°C. 4. Pour phase B into phase A. Add the components of phase C at 5.45°C. Add the components of phase D at 6.35°C. 7. Adjust the pH to 4.5-5.5 using the components of Phase E.

[0043] [Table 3]

[0044] Procedure for Example 3 1. Mix the components of phase B beforehand, and then add them to phase A. 2. Heat phase A (the main phase) to 70-75°C. Cool to 3.45°C. 4. Add the components of phase C and phase D. Add the components of phase E at 5.35℃.

[0045] [Table 4]

[0046] Components A to D are miscible with water and with each other. To prepare the facial cleanser of Example 4, heating and specifying the order of addition (to water) are not necessary.

[0047] [Table 5]

[0048] A sterilized stainless steel jacketed container equipped with a propeller mixer is used as the main container. Water is added to the main container and heating is started to 65°C. Phase 2 is pre-mixed in a separate container. The pre-mixed Phase 2 is added to Phase 1. The components of Phase 3 are pre-mixed in a separate container. The pre-mixed Phase 3 is added to the Phase 1-2 mixture at 65°C. The mixture is cooled to below 50°C, Phase 4 is added, and it is mixed until homogeneous.

[0049] [Table 6]

[0050] Ingredients marked with an asterisk are available from Vantage under the following brand names: * -METAUPON (trademark) EZ AMIBIO; ** -LIPONATE (registered trademark) Jojoba NATFILM (registered trademark); *** -CURAZAELIC(TM) 44; Vantage Specialty Ingredients, Inc. (Warren, NJ).

[0051] Add the components of Phase 1 to the main container and mix until uniform. Begin heating to 40°C. Premix LIPONATE® Jojoba NATFILM® with CURAZAELIC® 44. Add the components of Phase 2 to the main container one at a time in the order listed. Adjust the pH to 5.5-6.0 using Phase 3. Add the components of Phase 4 to the main container one at a time. Premix the components of Phase 5. Add the premixed Phase 5 to the main container and mix at a slow to medium speed until completely hydrated. Cool the batch.

[0052] [Table 7]

[0053] Ingredients marked with an asterisk are available from Vantage under the following brand names: **** -CURCYLIC (registered trademark)

[0054] Example 8 - ELISA immunoassay of tumor necrosis factor α (TNF-α) and caspase-1 (CASP-1) EpiDermFT (EFT-400, MatTek Europe, Bratislava Slovak Republic) is a multilayer reconstructed model of the human dermis and epidermis formed by culturing normal human epidermal keratinocytes (NHEK) and normal human dermal fibroblasts (NHFB). The epidermal portion of EpiDermFT is similar to the keratinized epidermis of living organisms, having basal cells expressing keratin 5 and a stratum spinosum and stratum granulosum expressing involucrin and keratin 10. The dermal portion consists of a collagen matrix containing viable normal human dermal fibroblasts (NHDF). Both the epidermal and dermal layers of EpiDermFT have mitotic and metabolic activity and exhibit morphological and proliferative characteristics similar to those of living organisms.

[0055] The EpiDermFT test was performed in 12-well plates filled with antibiotic-free culture medium at 37°C, 5% CO2, and saturated humidity (90% RH). Inoculum (6 μL of lipid mixture (olive oil and neutral triacylglycerol mixed in a 1:1 ratio) and C. acnes ATCC11827 (10 7 ~10 8 60 μL of CFU / mL was inoculated into EpiDerm tissue for 48 hours. (Concentration was determined by optical density at 450 nm using a spectrophotometer.) Excess inoculum was removed, and 5 μL of one of the three test products was inoculated into the tissue for a 24-hour treatment period. • Test group 1: 1% and 2% salicylic acid • Test Group 2: Concentrate of the present invention (containing 10% azelaic acid by active ingredient standard) • Test group 3: Combinations of 1% and 2% salicylic acid with 5% and 10% azelaic acid

[0056] At the end of the treatment period, the culture medium was collected and stored at -20°C. It was then analyzed by ELISA immunoassays for two inflammatory markers, TNF-α and CASP-1, using commercially available test kits (Quanikin® ELISA human caspase-1 / ICE immunoassay and human TNF-α immunoassay, both from R&D Systems, Inc. (Minneapolis, MN), catalog numbers DCA100 and DTA00D, respectively).

[0057] Group 1 showed an increased inflammatory response compared to the C. acnes treatment control group. Group 2 did not show an increase in TNF-α expression compared to the control group. Group 3 showed a measurable decrease in the expression of both TNF-α and CASP-1 compared to Group 1. All results were statistically increased compared to the negative control. See Figures 1-3.

[0058] ELISA also demonstrated that the concentrate of the present invention is less inflammatory than conventional suspensions containing azelaic acid at the concentration of the active ingredient.

[0059] Example 9 - In vivo treatment of post-inflammatory hyperpigmentation (PIH) PIH is a common acquired skin disorder that develops after inflammation or injury of the skin, and is more common and severe in people with darker skin tones whose Fitzpatrick skin phototype ("FST") is III-VI. (Fitzpatrick's skin phototype system classifies skin types based on the amount of skin pigment and the skin's response to sun exposure. Fitzpatrick, TB. Soleil et peau. J Med Esthet. 1975;2:33-34). PIH is caused by excessive melanin production or irregular dispersion of pigment after skin inflammation. Grimes PE. Semin Cutan Med Surg. 2009;28:77-85. In the epidermis, melanin production and its transfer to surrounding keratinocytes are increased. This increased melanocyte activity is associated with inflammatory mediators, including TNF-α. Davis EC and VD Callender, J Clin Aesthet Dermatol. 2010;3(7):20.

[0060] Sixty subjects (30 FST V and 30 FST VI) will be divided into three groups, each consisting of 10 FST V subjects and 10 FST VI subjects. Two of the groups will be treated for 8 weeks with two test products, namely placebo cream or a cream containing the concentrate of the present invention. A third, untreated group will serve as the control group. Subjects will be administered the test product (or placebo) once daily for 8 weeks. The primary endpoint, the degree of pigmentation, will be objectively measured using the "brown mode" of the RBX® technology of the VISIA® skin tone analysis system (Canfield Scientific, Parsippany, NJ, USA). RBX® technology converts a standard digital image, consisting of red (R), green (G), and blue (B) channels, into the RBX color space. The red and brown channels represent the distribution of hemoglobin and melanin, respectively. Secondary endpoints evaluated included the number of inflammatory and non-inflammatory acne lesions assessed by a dermatologist; skin moisture content (hydration level) using CORNEOMETER® (Courage+Khazaka electronic GmbH (“C+K”), Cologne, Germany); barrier function (transepidermal water loss) using TEWAMETER® (C+K); and porphyrin count under UV fluorescence using VISIA®. Measurements were taken at baseline, week 4, and week 8.

[0061] Participants also answered satisfaction questionnaires (0-10) evaluating their experience and skin tolerance, including burning, itching, and redness. The results of this study showed that formulations containing the concentrate of the present invention were able to statistically reduce post-inflammatory hyperpigmentation to a significantly better level than placebo or an untreated control group.

Claims

1. (a) Long-chain alkyldicarboxylic acids selected from the group consisting of adipic acid, azelaic acid, sebacic acid, and dodecanediic acid, which have low solubility in water and have 6 to 12 carbon atoms; and (b) Amidoamine; A substantially anhydrous dermatological concentrate consisting essentially of two components, When the ratio of a:b is 1:9 to 1:1, and the substantially anhydrous dermatological concentrate is added to water or a hydrophilic carrier, a clear solution is formed with a pH of less than 7 and in which no long-chain alkyldicarboxylic acid precipitates are visible to the naked eye. A virtually anhydrous dermatological concentrate.

2. The substantially anhydrous dermatological concentrate according to claim 2, wherein the ratio of a:b is 1:4 to 2:

3.

3. The substantially anhydrous dermatological concentrate according to claim 2, wherein the amidoamine is fatty acid amidopropyldimethylamine.

4. The substantially anhydrous dermatological concentrate according to claim 3, wherein the fatty acid amidopropyldimethylamine is cocamidopropyldimethylamine.

5. The substantially anhydrous dermatological concentrate according to any one of claims 1 to 4, wherein the long-chain alkyldicarboxylic acid is azelaic acid.

6. A method for producing a topical product comprising adding a substantially anhydrous dermatological concentrate according to any one of claims 1 to 5 to a hydrophilic carrier, wherein the long-chain alkyldicarboxylic acid is present in a concentration of at least 0.5% by weight based on the total weight of the topical product.

7. The method according to claim 6, wherein the topical product contains a long-chain alkyldicarboxylic acid in a concentration of at least 1% by weight.

8. The method according to claim 7, wherein the topical product contains a long-chain alkyldicarboxylic acid in a concentration of at least 5% by weight.

9. (a) A long-chain alkyldicarboxylic acid selected from the group consisting of adipic acid, azelaic acid, sebacic acid, and dodecanediic acid, which has low solubility in water and has 6 to 12 carbon atoms; (b) with salicylic acid; (c) with amidoamine; A substantially anhydrous dermatological concentrate essentially derived from, (i) a and b are present in a total amount up to 60% by weight of the substantially anhydrous dermatological concentrate; (ii) The ratio of b:c is 3:7 to 3:2; (iii) When the substantially anhydrous dermatological concentrate is added to water or a hydrophilic carrier, a clear solution is formed having a pH of less than 6 and in which (x) long-chain alkyl dicarboxylic acid precipitates and (y) salicylic acid precipitates are not visible to the naked eye; A virtually anhydrous dermatological concentrate.

10. The substantially anhydrous dermatological concentrate according to claim 9, wherein the amidoamine is fatty acid amidopropyldimethylamine.

11. The substantially anhydrous dermatological concentrate according to claim 10, wherein the fatty acid amidopropyldimethylamine is cocamidopropyldimethylamine.

12. A substantially anhydrous dermatological concentrate according to any one of claims 9 to 11, wherein the ratio of b:c is 2:3 to 11:

9.

13. The substantially anhydrous dermatological concentrate according to claim 12, wherein the alkylamide alkylamine is fatty acid amidopropyldimethylamine.

14. The substantially anhydrous dermatological concentrate according to claim 13, wherein the fatty acid amidopropyldimethylamine is cocamidopropyldimethylamine.

15. The substantially anhydrous dermatological concentrate according to any one of claims 9 to 14, wherein the long-chain alkyldicarboxylic acid is azelaic acid.

16. A method for producing a topical product containing a long-chain alkyldicarboxylic acid and salicylic acid, comprising the step of adding a substantially anhydrous dermatological concentrate according to any one of claims 9 to 15 to a hydrophilic carrier, wherein the topical product contains salicylic acid at a concentration of up to 5% based on the total weight of the topical product.

17. The method according to claim 16, wherein the topical product is used for the treatment of acne and contains salicylic acid at a concentration of 0.5% to 2.0% based on the total weight of the topical product.

18. The method according to claim 16, wherein the topical product is applied to the scalp and contains salicylic acid at a concentration of 1.8% to 3.0% based on the total weight of the topical product.

19. A topical product comprising a substantially anhydrous dermatological concentrate according to any one of claims 1 to 5 or 9 to 15, a hydrophilic carrier, and one or more surfactants.

20. The topical product according to claim 19, which does not contain sulfates.

21. The topical product according to claim 20, further comprising at least one taurine-based surfactant, preferably sodium methyl cocoyl taurate or sodium methyl oleoyl taurate.

22. The topical product according to claim 21, further comprising a secondary surfactant selected from the group consisting of cocamidopropyl betaine, sodium isethionate, sodium cocoyl isethionate, sodium lauroyl sarcosinate, sodium cocoyl glycine, disodium cocoyl glutamate, disodium laureth sulfosuccinate, and cocamidopropyl hydroxysultaine.

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