Abstract:
The present invention relates in general to products for topical application to the skin, and more particularly to improved stable emulsions for containing water soluble active ingredients, such as Vitamin C, glycolic acid, etc., which may nonetheless be packaged with gelatin capsules, and which have demonstrated improved stability. 
     In particular, the invention relates to a novel polyethylene glycol-in-oil emulsion that is compatible with gelatin capsules.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates in general to products for topical application to the skin, and more particularly to improved, stable emulsions for carrying active ingredients, such as for example, Vitamin C, glycolic acid, etc., the combination of which may be packaged in gelatin capsules, preferably soft gelatin capsules, as well as other packaging structures. In particular, the invention in its broad embodiments relates to a novel polyethylene glycol (PEG) in oil emulsion. These emulsions are in the preferred mode of packaging compatible with gelatin capsules. 
     Vitamin C, i.e., ascorbic acid, is known as being suitable for preventing or treating a variety of skin pathologies or diseases. Vitamin C is described as being protective of damage caused by UV-A and UV-B radiation. Among the diseases that can be treated or prevented with Vitamin C therapy, i.e., antioxidant therapy, are UV-B radiation-induced erythema, photoaging of the skin, skin cancer, etc. 
     It is known in the art that unmodified gelatin capsules are incompatible with water. Accordingly, typical emulsions (Oil-in-Water or Water-In-Oil) will degrade a capsule shell made of gelatin. The present novel methods and combination of ingredients permit the formation of cosmetically acceptable emulsions that will be tolerated by gelatin capsules. One additional advantage of these PEG-in-oil emulsions, in combination with gelatin capsules, is the capacity for use of an increased percentage of water soluble actives that can be encapsulated versus typical anhydrous bases which cannot tolerate water soluble actives. For example, ingredients such as vitamin C, which would have a low solubility in an anhydrous base, can be incorporated at higher levels using the emulsion systems of the present invention. 
     However, the use of PEG as the primary solubilizer for water soluble actives in gelatin capsules is not without additional problems in need of solving. In fact, from a cosmetic aesthetic perspective, the resultant emulsion carrier would in many applications be unacceptable, as PEG has a poor feel on the skin. 
     Thus, one difficulty overcome in developing such an emulsion system has been the modification of a predominately PEG-based product to create a better skin feel, so that it would (a) be aesthetically acceptable to the consumer, and (b) be encapsulatable in commonly used gelatin capsules. 
     Accordingly, one substantial advantage of the present invention is that water soluble actives can be dissolved into PEG, emulsified into an oil base with the resultant end product having a cosmetically acceptable feel, and still be compatible in ordinary gelatin capsules. 
     Some of the contemplated commercial uses for the present invention would be in the area of skin treatment cosmetics. Such inventive emulsions could, for example, be used for face or body products requiring certain designated water soluble actives which would be incompatible in an anhydrous base. 
     Other uses, advantages and objects of the improved emulsion systems of the present invention will become known to those skilled in the art upon review of the more detailed description of the present invention set forth hereinbelow. 
     SUMMARY OF THE INVENTION 
     The improved emulsions for topical application of the present invention are especially adapted for carrying a desired water soluble active ingredient which is insoluble or substantially insoluble in an anhydrous base. 
     In its broad parameters, the emulsions of the present invention for topical application include first and second emulsion phases, along with a dispersing agent(s) to create an emulsion therebetween. 
     The first emulsion phase includes polyethylene glycol (PEG) as a solvent, into which is dissolved a water soluble or substantially water soluble active ingredient, i.e., vitamin C or ascorbic acid, which is insoluble or substantially insoluble in an anhydrous base. 
     The second emulsion phase includes an oil, preferably selected from at least one silicone oil fluid, paraffin oils, vegetable oils, and mixtures thereof. 
     The invention also provides emulsions for topical administration comprising first and second emulsion phases and a dispersing agent(s). In this aspect, the first emulsion comprises PEG and a water soluble active ingredient which is insoluble or substantially insoluble in an anhydrous base. The second emulsion in this aspect comprises at least one silicone oil fluid. 
     Testing has shown that the improved topical application emulsions of the invention are suitable for forming stable vitamin C and other topical application products, which may be formulated with or without up to approximately 10% water, and which prove to have an acceptable stability. 
     The improved topical application emulsions of the present invention may be preferably applied to the skin of an individual in a gelatin capsule, which surrounds and encloses the emulsion, and which may be packaged therein according to known encapsulation methods. Particularly preferred gelatin capsules for use in the invention are &#34;twist-off&#34; gelatin capsules. 
     The invention further encompasses compositions and methods for treating and/or preventing skin damage caused by exposure to ultraviolet-A (UV-A) and ultraviolet-B (UV-B) radiation, including solar radiation. The inventive compositions include vitamin C dissolved or suspended in the topical emulsions of the invention. Further, such compositions are preferably administered to an individual or patient by way of a soft gelatin &#34;twist-off&#34; capsule. A gelatin capsule is a particularly preferred means for administering the vitamin C topical emulsion since the gelatin capsule prevents or decreases the oxidation of vitamin C by oxygen in the environment. Thus, the invention provides methods for antioxidant skin therapy, and specifically methods for treating or preventing UV-B radiation-induced erythema, photoaging of the skin, skin cancer, etc. 
     Further details and the substantial advantages of the improved topical application emulsions of the present invention will become more readily apparent to those skilled in the art upon review of the following detailed description of preferred embodiment, brief description of the drawing, the examples thereof and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a graph showing stability of vitamin C in vitamin C containing emulsions after 3 months at various temperatures, and comparing formulations made with no water versus 5% water. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The improved emulsions for topical application of the present invention are especially adapted for carrying at least one desired water soluble active ingredient that is insoluble or substantially insoluble in an anhydrous base. 
     Preferred embodiments of the emulsions of the present invention for topical application include first and second emulsion phases, along with a dispersing agent(s) to create an emulsion therebetween, utilizing procedures which are described in greater detail in the Examples set forth below. 
     In a particularly preferred embodiment, the first emulsion phase hereof includes polyethylene glycol as a solvent, and ascorbic acid (vitamin C) which is insoluble or substantially insoluble in an anhydrous base, and which may be preferably dissolved into the polyethylene glycol solvent. 
     The second emulsion phase comprises an oil or mixtures of oils. Suitable oils include silicone-derivative silicone oil fluids, paraffin oils, vegetable oils and mixtures thereof. A preferred second emulsion phase comprises at least one silicone-derivative silicone oil fluid, and an oil selected from the group consisting of paraffin oils, vegetable oils and mixtures thereof, some selected examples of which are set forth hereinafter. 
     In another preferred embodiment, the first emulsion phase includes polyethylene glycol, a water soluble active ingredient which is insoluble or substantially insoluble in an anhydrous base, and which may be preferably dissolved into the polyethylene glycol. In this embodiment, the second emulsion phase comprises a silicone-derivative silicone oil fluid. 
     The first emulsion phases of the invention may be solutions, suspensions, or dispersions of the active ingredient in the polyethylene glycol. Thus, the active ingredient may be substantially insoluble in the polyethylene glycol phase, i.e., the first emulsion phase. 
     As used herein, the term &#34;gelatin compatibility&#34; means no adverse interaction of the fill material with the gelatin capsule. 
     Actual testing by the inventors of the present invention has shown that the applicants&#39; improved topical application emulsions are suitable for forming stable vitamin C topical application products, which may be formulated with or without up to approximately 10% water, and which prove to have an acceptable stability. Other active ingredients have similarly been formulated into stable and useful emulsions according to the principles and teaching of the present invention. 
     By &#34;stable vitamin C topical emulsion application product&#34; and &#34;stable topical application emulsion&#34; are meant topical application emulsions that do not exhibit creaming, sedimentation, or phase separation. 
     It has been discovered that there is surprisingly little decomposition of vitamin C in the inventive topical application emulsions. 
     In one preferred embodiment, for example, the quantity of vitamin C which may be formulated for use in the improved emulsions of the present invention may comprise from about 0.1 to 10, more preferably from about 1.5 to 5, and most preferably about 1.5, weight percent of the total emulsion. 
     In some preferred embodiments, the first emulsion phase of the improved topical application emulsions invention may further include glycerin, and may also include water up to approximately 10 weight percent by total. However, water, and especially at elevated temperature levels, adversely effects the integrity of gelatin capsules since gelatin is water soluble. Accordingly, when the topical application emulsions are intended for encapsulation in gelatin capsules, the use of substantial amounts of water in the emulsions of the present invention must be closely monitored. The first emulsion phase may also include sodium chloride, and other ingredients, as described in the Examples hereof. 
     The second emulsion phase may, in addition to including at least one silicone-derivative silicone oil fluid, also contain a paraffin oil such as, for example, mineral oil and/or a vegetable oil. 
     The polyethylene glycol of the first phase of the improved topical application emulsions of the present invention may be included in amounts of approximately 20-80, and preferably 20-50, weight percent in preferred embodiments. 
     Suitable polyethylene glycols for use in the topical application emulsions have molecular weights of from about 200 to 6000, and preferably from 400 to 1000. 
     In addition to vitamin C, other representative water soluble active ingredients include, for example, glycolic acid, MFA fruit complex, other active ingredients, and mixtures thereof, in amounts of up to about 20 weight percent. 
     One dispersing agent suitable for use in the improved topical application emulsions of the present invention is a polysorbate. Representative polysorbates include Tween 20, a product of ICI Corporation described as a Polysorbate 20, and Tween 80, described as a Polysorbate 80. 
     The silicone-derivative silicone oil of the second phase of the present invention may comprise approximately 0-50, and preferably 0-40, weight percent of the final topical emulsion. As used herein the term &#34;silicone derivative silicone oil&#34; refers to one or more ingredients of the kind generally known to those skilled in the art as &#34;silicon oil.&#34; Examples without limitation include: 
     
         ______________________________________Silicone Fluids       Cyclomethicone244, 245, 344, 345Silicone Fluid       Laurylmethicone CopolyolQ2-5200Silicone Fluid       Cyclomethicone and Dimethicone Copolyol3225CAbil WE09   Polyglyceryl-4 Isostearate and Cetyl       Dimethicone Copolyol and Hexyl LaurateDow Corning 200       Dimethicone(various viscosities)Dow Corning 1401       Cyclomethicone and DimethiconolFluidDow Corning 1403       Dimethicone and DimethiconolFluid______________________________________ 
    
     The improved topical application emulsions of the present invention are set forth in the following Examples. 
     Preparation of Emulsions 
     The emulsions are made according to techniques known to those skilled in the art. Preservative and fragrance may optionally be added to the resulting emulsion formulations. 
     Once the appropriate emulsion is formulated, it can be encapsulated into conventional soft gelatin capsules in accordance with the rotary die process. Alternatively, the emulsions can be appropriately encapsulated in hard shell gelatin capsules as well as soft gelatin capsules. 
     Unless noted otherwise, the components listed for each of the formulations described in the following examples are indicated in parts by weight. 
     EXAMPLES 1, 2, AND 
     
         ______________________________________    Example 1 Example 2    (RDO95-51-2)              (RDO95-50-1A)                          Example 3______________________________________Phase IPEG-400    68.25       63.24       64.75Vitamin C- 1.50        1.50        1.50Ascorbic AcidGlycerin-USP      5.00        5.00        5.00Water      --          5.00        5.00Sodium Chloride      --          0.25        0.25Phase IISilicone Fluid      15.00       15.00       15.00245Silicone Fluid      9.00        9.00        9.003225CTween-20   1.50        1.50        1.505-Freeze Thaw      Acceptable  Acceptable  AcceptableCycles40° C. Oven      Acceptable  Acceptable  AcceptableStabilityRoom tempera-      Acceptable  Acceptable  Acceptableture StabilityGelatin capsule      Acceptable  Acceptable  Acceptablecompatibility______________________________________ 
    
     The emulsions of Examples 1, 2 and 3 were made according to blending methods and procedures known to those skilled in the art. 
     The stability of vitamin C in the Example 1 and Example 2 formulations in terms of the percent by weight of active vitamin C remaining in the formulation after exposure to various temperatures for 90 days is shown in FIG. 1. 
     EXAMPLES 4 and 
     
         ______________________________________            Example 4                    Example 5______________________________________Phase IPEG-400            58.75     36.00Vitamin C-Ascorbic Acid      1.50      1.50Glycerin-USP       --        5.00Ethoxylated-26     --        13.25GlycerinWater              8.00      8.80Sodium Chloride    0.25      0.25Pfaffia extract    --        0.28Pycnogenol         --        0.14Ecchnesia Extract  --        0.28Phase IIMineral oil        --        25.00Dow Corning Fluid 244              15.00     2.00ABIL WE 09         --        5.00Tween-20           2.50      --Dow Corning        9.00      --Fluid 3225CBorage Oil         --        1.00Vit-E Linoleate    --        0.50Vit-A Palmitate    --        0.50Crodoram Rhatania &#34;O&#34;              --        0.33Crodoram Nut &#34;O&#34;   --        0.16Caroplex           --        0.015-Freeze Thaw Cycles              Acceptable                        Acceptable40° C. oven Stability              Acceptable                        AcceptableRoom temperature stability              Acceptable                        AcceptableGelatin capsule    Acceptable                        Acceptablecompatibility______________________________________ 
    
     
         ______________________________________Stable PEG/Silicone Cream Formulations            Example 6Ingredient       (RDO91-118-2)______________________________________Phase 1:Transcutol       18.95PEG-1000         15.10PEG-400          15.20Glycerin-USP     5.00Water            2.00Glycolic Acid    1.00MFA Fruit Acid   3.00Germal 115       0.30Phase 2:Synchrowax HR-C  3.00D/C Silicone 345 20.55D/C Silicone 3225C            11.50D/C Silicone 556 2.00Tween-20         2.00Liquipar Oil     0.10Fragrance F94-238            0.305-Freeze Thaw Cycles            Acceptable40° C. Oven Stability            AcceptableRoom temperature AcceptablestabilityGelatin capsule  Acceptablecompatibility______________________________________ 
    
     
         ______________________________________Mineral Oil/PEG Emulsions           Example 7   Example 8Ingredient      (RDO95-31-1)                       (RDO95-40)______________________________________Phase I:PEG-400         53.55       36.00Ethoxylated-7 Glycerin           --          13.25Glycerin-USP    5.00        5.00Water           7.70        8.00Sodium Chloride 0.25        0.25Vitamin-C (Ascorbic Acid)           1.50        1.50Pfaffia/Ecchenesia/           --          1.25PycnogenolPhase II:Mineral Oil     25.00       25.00D/C Fluid 244   2.00        2.00Abil WE09       5.00        5.00Borage Oil      --          1.00Vit-E Linoleate --          0.50Vit-A Palmitate --          0.50Rhatania extract           --          0.50Crodoram Nut &#34;O&#34;           --          0.255-Freeze Thaw Cycles           Acceptable  Acceptable40° C. Oven Stability           Acceptable  AcceptableRoom temperature           Acceptable  AcceptableStabilityGelatin capsule Acceptable  Acceptablecompatibility______________________________________ 
    
     
         ______________________________________Vegetable Oil/Silicone Emulsions          Example 9   Example 10Ingredient     (RDO95-39-1)                      (RDO95-39-2)______________________________________Phase I:PEG-400        53.55       36.00Ethoxylated-7 Glycerin          --          13.25Vitamin-C (Ascorbic Acid)          1.50        1.50Glycerin       5.00        5.00Water          7.70        8.00Sodium Chloride          0.25        0.25Phase II:Olive Oil      25.00       25.00Silicone Fluid 244          2.00        2.00Abil WE09      5.00        5.00Borage Oil     --          2.005-Freeze Thaw Cycles          Acceptable  Acceptable40° C. Oven Stability          Acceptable  AcceptableRoom temperature          Acceptable  AcceptableStabilityGelatin capsule          Acceptable  Acceptablecompatibility______________________________________ 
    
     The following table lists the source and generic name of various materials employed or suitable for use in the compositions of the invention. 
     
         ______________________________________Ingredient  Source       Generic Name______________________________________PEG-400, PEG-600,       Union Carbide                    Polyethylene GlycolPEG-1000Silicone Fluids       Dow-Corning  Cyclomethicone244, 245, 344, 345Silicone Fluid       Dow-Corning  Cyclomethicone and3225C                    Dimethicone CopolyolTween-20    ICI Americas Polysorbate-20Protochem GL-7,       Protameen    Ethoxylated-7GL-26       Chemical     Glycerin and                    Ethoxylated-26                    GlycerinABIL WE-09  Goldschemidt Polyglyceryl-4                    Isostearate and cetyl                    Dimethicone Copolyol                    and Hexyl LaurateDown-Corning       Dow-Corning  DimethiconeFluid 200Dow-Corning Dow-Corning  Cyclomethicone andFluid 1401               DimethiconolDow-Corning Dow-Corning  Dimethicone andFluid 1403               DimethiconolCeraphyl 31 ISP-Vandyk   Lauryl LactateScheremol DIA       Scher and Co.                    Diisopropyl AdipateMFA-Complex Barnett and Co.                    Alpha hydroxy Acid                    ComplexDry-Flow PC National Starch                    Aluminum Starch                    OctylsuccinateSyncrowax HR-C       Croda        Glyceryl BehenateCrodoram Rhatania       Croda        Rhatania Root Extract&#34;O&#34;Crodoram Nut &#34;O&#34;       &#34;            Walnut ExtractCaroplex    Quest        Caroteen MixturePfaffia     NAT-TROP     Pfaffia extractEchenesia extract       East Earth herb                    Coneflower extractPycnogenol  TAAG and Co. Martime Pine extractBorage Oil  Cannamino and                    Borage Oil       Co.Vitamin E Linoleate       Hoffman-LaRoche                    Tocopheryl linoleateVitamin A Palmitate       Hoffman-LaRoche                    Retinyl palmitate______________________________________ 
    
     The basic and novel characteristics of the improved methods, compositions of matter, and combination of ingredients of the present invention will be readily understood from the foregoing disclosure by those skilled in the art. It will become readily apparent that various changes and modifications may be made in the form, construction and arrangement of the improved formulations of the present invention, and in the steps of the inventive methods hereof, which various respective inventions are as set forth hereinabove without departing from the spirit and scope of such inventions. Accordingly, the preferred and alternative embodiments of the present invention set forth hereinabove are not intended to limit such spirit and scope in any way.