Method for producing a starting formulation for a dermatological sunscreen preparation and for producing a dermatological sunscreen preparation

Abstract

Method for producing a starting formulation for a dermatological sun protection preparation, wherein the starting formulation comprises an oil phase and an aqueous phase and contains at least one UV-absorbing substance and at least one amphiphilic substance that forms lamellar structures, in which an oil phase is produced comprising at least one triglyceride and at least one UV-absorbing substance, and this oil phase is heated and homogenized in a first step to at least 80 °C, and at least one UV-absorbing inorganic substance is added in a second step at at least 70 °C; an aqueous phase is produced comprising at least one amphiphilic substance, and this aqueous phase is heated and homogenized to at least 70 °C; Both phases are combined and the combined product is homogenized.

Description

[0001] The present invention relates to a method for producing a starting formulation for a dermatological sun protection preparation according to claim 1, and a method for producing a dermatological sun protection preparation according to claim 15.

[0002] Various dermatological sun protection preparations and their manufacturing processes are known from the prior art. For example, in particular from DE 10 2006 045 388 A1, DE 10 2006 045 389 A1, DE 10 2010 037 961 A1, DE 693 18 912 T2, DE 60 2004 012 213 T2, DE 60 2004 013 358 T2 or also from DE 60 2005 001 028 T2.

[0003] Sunscreens, in general, are designed to protect the skin from excessive UV radiation. They are most commonly found in the form of sunscreen lotion. Sunscreen lotion is a liquid emulsion consisting of both oil and water. However, sunscreens are also available as creams, oils, or water-based gels. Sunscreens with a low water content are ointment-like, while those with a high water content are more like lotions.

[0004] Conventional dermatological sunscreens are generally based on a mixture of known and proven combinations of active ingredients and excipients. According to current medical knowledge, and especially from a consumer perspective, not all of these active ingredients and excipients are still desirable in cosmetics and skincare products. For many of these substances, their mode of action as individual components or as a mixture, their absorption in the body, their release rate, the site of release, and the site of action are often uncertain. While this may be tolerated in cosmetics for intact skin due to their high barrier and repair capacity, it can, particularly in sensitive or damaged skin, reverse the intended positive effect of the product.

[0005] Restrictive regulations regarding permissible active ingredients and excipients can be found in the European Cosmetics Regulation EC VO 1223 / 2009.

[0006] In sun protection preparations, chemical and physical filter substances are typically used as active ingredients to block UV radiation.

[0007] Chemical filters, for example in a preparation as described in DE 693 189 12 T2, are indeed extremely efficient, as their effect can last a particularly long time due to the absorption behavior of the skin. However, they are suspected of potentially triggering allergic reactions or cell damage.

[0008] Physical filters consist of very finely ground minerals, preferably metal oxides such as titanium dioxide, zinc oxide, or aluminum oxide, and their filtering effect is purely physical, achieved through scattering, reflection, and partial absorption of UV light with the accompanying energy conversion. Their advantage is that they are chemically inert and therefore neither decompose nor cause allergic reactions (with the exception of aluminum oxide, which is excluded for the purposes of this invention). However, a disadvantage is that the protective layer from the applied sunscreen can be easily washed off by water or perspiration. Unintentionally and often unnoticed, this can lead to skin damage from UV light, necessitating more frequent reapplication, which is detrimental to the user.

[0009] To improve user comfort and skin compatibility of sunscreens, it is desirable, for the reasons mentioned above, that sunscreens contain predominantly physical filters, offer long-lasting protection, and are also water-resistant. Furthermore, sunscreens should be manufactured efficiently and economically.

[0010] Therefore, a simple manufacturing process for a dermatological sun protection preparation would be desirable, in which the proportion of undesirable substances is significantly reduced, if not completely eliminated, in relation to the harmless excipients and active ingredients, in order to minimize undesirable effects.

[0011] Preparations based on lamellar layer systems, preferably so-called "hydrogenated liposomes," have proven to be particularly promising sun protection products. Such lamellar layer systems and their manufacturing processes are disclosed, for example, for cosmetic facial and lip care in DE 10 2006 045 388 A1 and DE 10 2006 045 389 A1.

[0012] However, known manufacturing methods have proven to be less than ideal in practice. Sunscreen preparations produced in this way, containing a liposomal phase and integrated chemical and physical filters, as described in particular in DE 10 2006 045 388 A1, are not stable; phase separation occurs. Furthermore, the manufacturing process is very complex, not readily scalable, and therefore neither efficient nor easy to handle.

[0013] It is therefore an object of the invention to provide a method for producing a starting formulation for a dermatological sun protection preparation which overcomes the aforementioned disadvantages of the prior art.

[0014] In accordance with the invention, the starting formulation comprises an oil phase and an aqueous phase, and contains at least one UV-absorbing substance and at least one amphiphilic substance that forms lamellar structures, preferably a system of lamellar structures. Lamellar structures form systems characterized by a regular, layered structure. In the human body, such structures are found as lipid bilayers in cell membranes.

[0015] Topical lamellar systems are generally based on natural models and use phosphatidylcholine, ceramides, sterols and fatty acids as structure-forming elements.

[0016] However, in accordance with the invention, lamellar systems can also be formed by many synthetic surfactants if they are present in a sufficiently high concentration and these amphiphilic substances allow a double-layer arrangement due to their molecular structure, i.e., a balanced ratio of hydrophilic and lipophilic molecular parts.

[0017] However, the formation of lamellar structures of hydrogenated lipids is not spontaneous, but requires a high energy input in the form of temperature and possibly mechanical energy (for example, homogenization under pressure) during production, especially during barrier constitution.

[0018] In accordance with the invention, the following is produced for the manufacture of a starting formulation for a dermatological sun protection preparation: - an oil phase comprising at least one emollient, preferably a triglyceride, and the essential content of UV-absorbing substances, and heating and homogenizing this oil phase in a first step to at least 80 °C, preferably at least 90 °C, preferably up to a maximum of 96 °C; and mixing in at least one UV-absorbing inorganic substance in a second step at at least 70 °C, preferably at least 75 °C, preferably up to a maximum of 82 °C; - an aqueous phase comprising the essential content of amphiphilic substance, and heats and homogenizes this aqueous phase to at least 70 °C, preferably at least 80 °C, preferably to a maximum of 86 °C; combines both phases, optionally with the addition of at least one further UV-absorbing substance, and homogenizes the combined product.

[0019] In preferred processes, the starting formulation contains an oil phase with a proportion of 30 to 50 wt%, preferably 25 to 40 wt%, or even 35 to 45 wt%, and a water phase with a proportion of 30 to 40 wt%, preferably 25 to 40 wt%, or even 35 to 45 wt%.

[0020] In a preferred embodiment of a method according to the invention, the starting formulation contains an oil phase and a water phase in a ratio of 1:4 to 4:1, preferably 1:3 to 3:1 and particularly preferably 1:2 to 2:1.

[0021] In a preferred embodiment of a method according to the invention, the initial formulation contains predominantly, preferably almost, and for special applications exclusively, an oil phase as well as a small proportion of less than 10% by weight, preferably less than 5% by weight, of a water phase.

[0022] In preferred processes, the oil phase contains at least one, preferably two, medium-chain triglycerides selected from esterification products of glycerol with capric acid and caprylic acid in a ratio of 1:3, preferably capryl triglycerides, and coco-triglycerides.

[0023] In the process according to the invention, the oil phase contains as a UV absorber a hexyl benzoate, preferably a 2-[4-(Diethylamino)-2-hydroxybenzoyl]-benzoic acid hexyl ester and / or a bemotrizinol, and / or a cyanurtriamide and / or an ethylhexyl triazone, and / or a, preferably coated, TiO2.

[0024] According to the invention, coated TiO2 is a TiO2 powder whose particles have been coated with a silicate layer. This has the advantage that the coating results in a higher UV absorption rate compared to uncoated TiO2, thus providing greater protection against UV radiation with the same amount of TiO2.

[0025] In preferred processes, the oil phase contains a proportion of phytosqualane of 0.5 to 6.5 percent by weight.

[0026] In preferred processes, the oil phase contains an alkyl benzoate content of 3.5 to 9.5 percent by weight.

[0027] In preferred processes, the oil phase contains a proportion, preferably coated, of TiO2 of 6.5 to 15.5 percent by weight as a physical filter material. Experiments have shown that TiO2, preferably coated, in the form of nanocrystalline powder with an average particle size of less than 30 nm to 25 nm, preferably less than 25 nm to 20 nm, more preferably less than 20 nm to 15 nm or less than 15 nm to 10 nm, and most preferably less than 10 nm to 5 nm, is particularly suitable.

[0028] In preferred processes, the aqueous phase contains an amphiphilic substance, preferably hydrogenated phosphatidylcholine, at a concentration of 0.5 to 5.5 percent by weight.

[0029] Hydrogenated phosphatidylcholine has a particularly suitable fatty acid composition, consisting of saturated C 18 - and C 16 -acids, which determine the planar structure of a bilayer.

[0030] In preferred methods, fractionated native phosphatidylcholine with a high linoleic acid content of 80 to 90 wt% in the fatty acid composition is preferably obtained from soy lecithin by column chromatography, which generates cellular bilayers. Such bilayers, also known as liposomes, enhance the penetration of active ingredients, especially physical filters.

[0031] In preferred methods, by adjusting suitable mixing ratios of the oil phase and / or water phase and / or the UV-absorbing and / or UV-absorbing inorganic substances and / or amphiphilic substances contained therein, a starting formulation with a high transport rate of active ingredients and a very low wash-out effect from the skin can be continuously adjusted.

[0032] In the process according to the invention, the aqueous phase contains glycerin and / or glycol, preferably pentylene glycol.

[0033] In preferred processes according to the invention, at least one polysaccharide, preferably an anionic mixed polysaccharide, is added to the aqueous phase.

[0034] In accordance with the invention, the addition of at least one gelling agent, preferably the aforementioned polysaccharide or a carbomer, serves to stabilize the lamellar structures or the lamellar system against changes in consistency or lysophosphatidylcholine formation (cleavage of fatty acid residues by hydrolysis).

[0035] In preferred processes, the oil phase is heated in the first step to a maximum temperature of 83 °C, preferably 88 °C, preferably 92 °C and particularly preferably 97 °C and / or in the second step to a maximum temperature of 76 °C, preferably 81 °C and particularly preferably 86 °C and / or the water phase to a maximum temperature of 72 °C, preferably 75 °C and particularly preferably 78 °C.

[0036] In preferred methods, the further UV-absorbing substance is a UV-A / UV-B absorber, preferably based on bisoctrizole.

[0037] In a process according to the invention for producing a dermatological sun protection formulation, a second aqueous phase is produced which contains at least one polyalcohol in addition to water; and the starting formulation according to the invention is mixed with the second aqueous phase at a temperature of at least 60 °C and the mixture is homogenized.

[0038] Preferably, the at least one polyalcohol of the second aqueous phase comprises a glycerol and / or a glycol, preferably pentylene glycol.

Claims

A process for producing a starting formulation for a dermatological sunscreen preparation, wherein the starting formulation comprises an oil phase and an aqueous phase and contains at least one UV-absorbing substance and at least one amphiphilic substance forming lamellar structures, in which an oil phase is produced comprising at least one triglyceride and the at least one UV-absorbing substance, and this oil phase is heated and homogenized in a first step to at least 80 °C, and at least one UV-absorbing inorganic substance is added in a second step at at least 70 °C; an aqueous phase is produced comprising the at least one amphiphilic substance, and this aqueous phase is heated and homogenized to at least 70 °C; both phases are combined, and the combined product is homogenized. The method of claim 1, wherein the two phases are combined by adding at least one further UV-absorbing substance and the combined product is homogenized. Method according to one of the preceding claims, wherein the oil phase contains at least one or two medium-chain triglycerides selected from caprylic triglycerides and coco-triglycerides. A method according to any of the preceding claims, wherein the oil phase contains as a UV absorber a. a hexyl benzoate, and / or b. a bemotrizinol, and / or c. an ethylhexyl triazone, and / or d. a TiO2, and / or e. a coated TiO2. Method according to one of the preceding claims, wherein the oil phase contains a proportion of phytosqualane of 1 to 6 percent by weight. Method according to one of the preceding claims, wherein the oil phase contains a proportion of alkyl benzoate of 3.5 to 6.5 percent by weight. Method according to one of the preceding claims, wherein the oil phase contains a proportion of TiO2 of 7 to 15 percent by weight. Method according to one of the preceding claims, wherein the UV-absorbing substances in the oil phase to the UV-absorbing inorganic substance is in a ratio of at least 1:1, or at least 1:2, or at least 1:1.5, or at least 1:3, and does not exceed a ratio of at most 1:

4. Method according to any of the preceding claims, wherein the aqueous phase contains an amphiphilic substance in a concentration of 0.5 to 5 percent by weight. Method according to any of the preceding claims, wherein the aqueous phase contains glycerin and / or glycol. Method according to one of the preceding claims, wherein the oil phase is heated in the first step to a maximum temperature of 83 °C, or of 88 °C, or of 92 °C or of 97 °C and / or in the second step to a maximum temperature of 76 °C, or of 81 °C or of 86 °C and / or the water phase is heated to a maximum temperature of 72 °C, or of 75 °C or of 78 °C. Method according to any of the preceding claims, wherein the further UV absorbing substance is a UV-A / UV-B absorber. Method according to claim 12, wherein the further UV absorbing substance is a bisoctrizole-based UV-A / UV-B absorber. Method for producing a dermatological sun protection formulation, in which a second aqueous phase is generated which contains at least one polyalcohol in addition to water; and the starting formulation according to claim 1 is mixed with the second aqueous phase at a temperature of at least 60 °C and the mixture is homogenized. Method according to claim 14, wherein the at least one polyalcohol of the second aqueous phase comprises a glycerol and / or glycol.