WO1997009027A1

WO1997009027A1 - Cosmetic composition of an alpha or beta-hydroxy acid and a polyvinylpyrrolidone complexing agent

Info

Publication number: WO1997009027A1
Application number: PCT/US1996/010781
Authority: WO
Inventors: John J. Merianos; Ratan K. Chaudhuri; Anna A. Gripp; Salvatore J. Guccione; Russell B. Biss
Original assignee: Isp Investments Inc.
Priority date: 1995-09-01
Filing date: 1996-06-24
Publication date: 1997-03-13
Also published as: AU6391996A

Abstract

What is described herein is a cosmetic composition of an alpha-hydroxy acid, such as lactic acid or glycolic acid, or a beta-hydroxy acid, such as salicylic acid, and a polyvinylpyrrolidone-complexing agent, or derivative thereof, in a suitable solvent, useful for the treatment of skin problems, with only minimal skin irritation for the user.

Description

COSMETIC COMPOSITION OF AN

ALPHA OR BETA-HYDROXY ACID AND A

POLYVINYLPYRROLIDONE COMPLEXING AGENT

BACKGROUND OF THE INVENTION

This invention relates to cosmetic compositions, and more particularly, to cosmetic compositions containing an alpha- or beta-hydroxy acid and an anti-irritant agent.

Cosmetic compositions having an alpha- or beta- hydroxy acid as the active ingredient are well known in the art. These compositions are useful for treatment of the skin, particularly for anti-aging, improvement in skin tone, reduction of fine line, enhancement of moisture, and development of a smooth skin. Application of these compositions generally results in a younger- looking skin as new cells replace the old. However, to achieve this improvement in skin condition, it is necessary for the user to tolerate the skin irritation caused by the acid present in the product. Accordingly, skin irritation is a major concern to formulators of compositions of alpha and beta-hydroxy acids, particularly as higher acid levels deliver faster and more effective skin peeling, even though more irritation is perceived by the user as being a more effective treatment.

SUMMARY OF THE INVENTION

In this invention, there is described a cosmetic composition including an alpha-hydroxy acid, such as lactic acid or glycolic acid, or a beta-hydroxy acid, such as salicylic acid, and a polyvinylpyrrolidone- complexing agent, or derivative thereof, in a suitable solvent. DETAILED DESCRIPTION OF THE INVENTION

The cosmetic composition of the invention comprises an alpha-hydroxy acid or a beta-hydroxy acid, and a polyvinylpyrrolidone-complexing agent for the acid. The presence of the PVP-complexing agent in the composition reduces the irritation effect of the acid without affecting its efficacy.

Suitable polyvinylpyrrolidone-co plexing agents for use herein include polyvinylpyrrolidone (PVP) , and derivatives thereof, such as an alkylated PVP. Preferably the PVP-complexing agent is water soluble. Generally the amount of the PVP-complexing agent in the composition is sufficient to effect a substantial or complete reduction in any skin irritation experienced by the user without affecting the desired improvement in skin condition. This effective amount of PVP may effect a partial or complete complexation of the acid.

The alpha-hydroxy acid of the invention suitably is selected from the group consisting of lactic acid and glycolic acid, and the beta-hydroxy acid is salicylic acid, both as the free acid or salt thereof, and mixtures thereof.

The cosmetic composition or concentrate of the invention may be in the form of a solution, powder, gel or emulsion. As a powder, the composition may contain up to about 10-20% of the acid, while in solution, gel or emulsion form, a lesser amount of the acid may be used, by dilution of the concentrate. In solution, about 1-10% by weight of the acid and 1-10% by weight of PVP is present.

The solvent for the cosmetic composition herein may be water or an organic solvent such as ethyl acetate or ethyl alcohol, and mixtures thereof. The acid itself may be commercially available in aqueous solution only. e.g. lactic acid is sold as an 88% aqueous solution, and it can be used directly in preparing the composition. An organic solvent then may be included during preparation of the composition.

A powder of the composition may be prepared by reacting substantially stoichiometric amounts of the acid and PVP-complexing agent, in a suitable solvent, precipitating the acid-PVP complex from the reaction mixture, and drying.

The invention will be described hereinafter with reference to the following working examples.

EXAMPLE A

A cosmetic composition was prepared from 12 g of an 88% by weight aqueous solution of lactic acid, 22 g of polyvinylpyrrolidone (PVP-K30) , a water soluble form available from International Specialty Products, as PVP- CI, and 300 ml of ethyl acetate. The composition was prepared by forming a suspension of the PVP-CI in ethyl acetate and adding the aqueous lactic acid solution slowly with stirring. The resultant concentrate contains 3.16% by weight lactic acid and 6.6% by weight of PVP. Efficacious skin care products are prepared from the concentrate, are formulated with only minimum skin irritation.

EXAMPLE B

A powder form of the composition of Example A was prepared by following the procedure of Example A, and, thereafter, precipitating a complex of the lactic acid and PVP, decanting the ethyl acetate, and drying the green precipitate at 50-60° under vacuum. 23.5 g of a white powder which included 17.4% lactic acid was obtained. The powder then is formulated into efficacious skin care products. EXAMPLE C

The procedures of Examples A and B were repeated using 15 g of salicylic acid in place of lactic acid, 85 g of PVP-CI and 250 ml ethyl acetate. 467 g of a powder which analyzed for 9.5% salicylic acid was obtained. The products also are useful as an efficacious skin care product with only minimum skin irritation.

In another form of the invention, there is provided a cosmetic composition for the treatment of skin problems with minimal skin irritation, in the form of a lotion, creme, solution or gel comprising an aqueous, alcoholic or aqueous-alcoholic solution of a hydroxy acid, and a vinylpyrrolidone-based polymer, copolymer, graft polymer or lightly crosslinked polymer, and mixtures thereof as anti-irritation and anti-erythema agent therefor, said solution having a pH of about 1.5 to about 5.0.

Accordingly, a cosmetic composition for rejuvenating the appearance of the skin, which composition includes a hydroxy acid, such as an alpha hydroxy acid (AHA) or a beta-hydroxy acid (BHA) and a defined vinyl pyrrolidone (VP)-based polymer, copolymer, graft polymer or lightly crosslinked polymer, and mixtures thereof as anti-irritant and anti-erythema agent thereof.

The general formulation is given below in Table 1: TABLE 1

Compositioη % bv Wt.

Essential Components Suitable Preferred

Hydroxy acid, e.g. AHA or BHA 0.5 to 15 1-10

PVP-Based Polymer,

Copolymer, Graft or Lightly Crosslinked Polymer, Anti-Irritant and Anti-Erythema Agent

Water

Optional Components

Emollient

Moisturizer

Emulsifier

Thickener

Neutralizer

Preservative pH

Ratio of PVP-Based Polymer/AHA or BHA 1:1 to 1:20 1:2 to 1:10

Hydroxy Acids

Suitable hydroxy acids for use herein are AHA and BHA compounds, such as lactic acid, glycolic acid, citric acid, tartaric acid, malic acid (AHA) or salicylic acid (BHA) .

Vinylpyrrolidone-Based Polymer

The vinylpyrrolidone-based is the effective anti-irritating and anti-erythema agent herein. Suitable vinylpyrrolidone-based agents include polyvinylpyrrolidone polymers; C₄-C₃₀ alkyl polyvinyl- pyrrolidones having a molecular weight (viscosity average) in the range from about 1500 to about 1,500,000, preferably from about 3000 to about 700,000, more preferably from about 5000 to about 100,000; or vinylpyrrolidone/vinyl acetate (VP-VA) copolymers. Among the examples of such vinylpyrrolidone-based polymers include polyvinylpyrrolidone (PVP) itself, butylated polyvinylpyrrolidone, and vinylpyrrolidone-vinyl acetate copolymer (molar ratio 60/40 to 95/5) . A preferred vinylpyrrolidone-based agent herein is polyvinyl¬ pyrrolidone made from recrystallized vinyl pyrrolidone (VP) , and polymerized with t-butylhydroperoxide initiator. Such PVP is substantially colorless because of the absence of residual vinyl pyrrolidone monomer or 2-pyrrolidone.

Other vinylpyrrolidone-based co plexing agents for use herein include C₄-C₁₈ alkyl or hydroxyalkyl pyrrolidones such as lauryl polyvinylpyrrolidone.

The lightly crosslinked strongly swellable polyvinylpyrrolidone (LXL-PVP) powder, described by Jenn Shih, in U.S. Pats. 5,073,614; 5,139,770; and 5,162,417, are particularly suitable for use herein. Such LXL-PVP polymer powders also provide a thickening function in the cosmetic compositions of the invention.

In general, suitable vinylpyrrolidone-based polymers for use herein thus include:

PVP K15, K30, K60, K90 (K value indicates viscosity grades) (ISP); P(VP-VA) S 630, W 735, E or I 535 grades (ISP); Ganex® 220, P904, 516, 660 (ISP); and Polectron® 430 (ISP) ; lightly crosslinked PVP (LXL-PVP) (ISP).

The vinylpyrrolidone-based polymer is present in the composition herein at a loading level of from about 0.1% to about 10%, preferably from about 1% to about 3%, by weight of the composition. The weight ratio of vinylpyrrolidone-based polymer agent to hydroxy acid, e.g. AHA or BHA, is in the range from about 1:1 to about 1:20, preferably from about 1:2 to about 1:10.

Emollient

Suitable emollients for use herein include, for example, optionally hydroxy-substituted C₈-C₅₀ unsaturated fatty acids and esters thereof, C₁-C ₄ esters of C₈-C₃₀ saturated fatty acids such as isopropyl myristate, cetyl pal itate and octyldodecylmyristate (Wickenol 142) , beeswax, saturated and unsaturated fatty alcohols such as behenyl alcohol and cetyl alcohol, hydrocarbons such as mineral oils, petrolatum and squalane, fatty sorbitan esters, lanolin and lanolin derivatives, such as lanolin alcohol ethoxylated, hydroxylated and acetylated lanolins, cholesterol and derivatives thereof, animal and vegetable triglycerides such as almond oil, peanut oil, wheat germ oil, linseed oil, jojoba oil, oil of apricot pits, walnuts, palm nuts, pistachio nuts, sesame seeds, rapeseed, cade oil, corn oil, peach pit oil, poppyseed oil, pine oil, castor oil, soybean oil, avocado oil, safflower oil, coconut oil, hazelnut oil, olive oil, grapeseed oil, and sunflower seed oil and C^C^ esters of di er and trimer acids such as diisopropyl dimerate, diisostearyl alate, diisostearyldi erate and triisostearyltrimerate.

Suitable emollients for use herein thus include isocetyl alcohol, octyl palmitate, isostearyl neopentanoate and isocetyl stearyl stearate, natural and synthetic oils selected from mineral, vegetable, and animal oils, fats and waxes, fatty acid esters, fatty alcohols, alkylene glycol and polyalkylene glycol ethers and esters, fatty acids and mixtures thereof. Preferred emollients are selected from hydrocarbons such as isohexadecane, mineral oils, petrolatum and squalane, lanolin alcohol, and stearyl alcohol. These emollients may be used independently or in mixtures and may be present in the composition of the present invention in an amount from about 1% to about 30% by weight, and preferably are present in an amount from about 5% to about 15% by weight of the total composition.

Emulsifier

Suitable emulsifiers for use herein include glyceryl stearate and laureth 23, PEG 20 stearate, and mink-a idopropyl dimethyl 2-hydroxyethylammonium chloride.

Moisturizer

Typical moisturizers are glycerin, petrolatum and maleated vegetable oil.

Thickener

The compositions of the invention can also contain a hydrophilic gelling agent at a level from about 0.01% to about 10%, preferably from about 0.02% to about 2%, and especially from about 0.02% to about 0.5%. The gelling agent preferably has a viscosity (1% aqueous solution, 20°C. , Brookfield RVT) of at least about 4000 Pa.s, more preferably at least about 10,000 Pa.s and especially at least 50,000 mPa.s.

Suitable hydrophilic gelling agents can generally be described as water-soluble or colloidally water-soluble polymers, and include cellulose ethers (e.g. hydroxyethyl cellulose, methyl cellulose, hydroxypropylmethyl cellulose) , polyvinylalcohol, polyquaternium-10, guar gum, hydroxypropyl guar gum and xanthan gum. Among suitable hydrophilic gelling agents are acrylic acid/ethyl acrylate copolymers and the carboxyvinyl polymers sold by the B.F. Goodrich Company under the trademark of Carbopol® resins. These resins consist essentially of a colloidally water-soluble polyalkenyl polyether crosslinked polymer of acrylic acid crosslinked with from 0.75% to 2.00% of a crosslinking agent such as for example polyallyl sucrose or polyallyl pentaerythritol. Examples include Carbopol 934, Carbopol 940, Carbopol 950, Carbopol 980, Carbopol 951 and Carbopol 981. Carbopol 934 is a water-soluble polymer of acrylic acid crosslinked with about 1% of a polyallyl ether of sucrose having an average of about 5.8 allyl groups for each sucrose molecule. Also suitable for use herein are hydrophobically-modified crosslinked polymers of acrylic acid having amphipathic properties available under the Trade Name Carbopol 1382, Carbopol 1342 and Pe ulen TR-1 (CTFA Designation: Acrylates/10-30 Alkyl Acrylate Crosspolymer) . A combination of the polyalkenyl polyether cross-linked acrylic acid polymer and the hydrophobically modified cross-linked acrylic acid polymer is also suitable for use herein. Other suitable gelling agents suitable for use herein are oleogels such as trihydroxystearin and aluminum magnesium hydroxy stearate.

Preferred thickeners for use herein include crosslinked aleic anhydride-alkyl ethylethers, and copolymers, sold as Stabileze® QM (International Specialty Products (ISP)). Also useful are Carbomer®, natural gums, highly crosslinked polymethacrylate copolymer such as Microsponges® 5647, which take the form of generally spherical particles of crosslinked hydrophobic polymer having a pore size of from about 0.01 to about 0.05 μm and a surface area of 200-300 m²/g. Again, it is preferably loaded with humectant in the levels described above. The lightly crosslinked, strongly swellable PVP provided by Shih (see above) can provide the desired anti-irritant and anti-erythema properties for the hydroxy acid, and, also, the desired thickener action for the composition.

Neutralizer

Neutralizing agents suitable for use in neutralizing acidic group containing hydrophilic gelling agents herein include sodium hydroxide, potassium hydroxide, ammonium hydroxide, monoethanolamine, diethanolamine and triethanolamine, and aminomethyl propanol.

Other Optional Components

Another optional but preferred component of the composition is one or more preservatives. The preservative concentration in the composition, based on the total weight of that composition, is in the range of between about 0.05% and about 1.0% by weight, preferably between abut 0.1% and about 0.4% by weight. Suitable preservatives for use herein include sodium benzoate and propyl paraben, and mixtures thereof.

The composition may also contain additional materials such as, for example, fragrances, fillers such as nylon, sun-screens, electrolytes such as sodium chloride, proteins, antioxidants and chelating agents as appropriate.

Another optional component is one or more ultraviolet absorbing agents. Ultraviolet absorbing agents, often described as sunscreening agents, can be present in a concentration in the range of between about 1% and about 12% by weight, based on the total weight of composition. Preferably, the UV absorbing agents constitute between about 2% and 8% by weight. More preferably, the UV absorbing agents can be present in the composition in a concentration range of between about 4% and about 6% by weight. Of the ultraviolet absorbing agents suitable for use herein, benzophenone-3, benzophenone-4, octyl dimethyl PABA (Padimate 0), octyl methoxy cinnamate, octyl salicylate, octocrylene, p-methylbenzylidene camphor, butyl methoxy dibenzoyl methane (Parsol 1789) and mixtures thereof are particularly preferred.

EXAMPLES 1-3 A skin creme composition containing Plasdone® K29/32 (ISP) and 10% glycolic acid was formulated as follows:

Base Composition

Water Phase

H₂0, deionized Stabileze® QM (ISP) Plasdone® K 29/32 (ISP) Suttocide® A (Sutton)

Alpha-Hydroxy Acid

Glycolic acid (70%) 10% solids (Aldrich) 14.29 14.29 14.29

Neutralizer

Sodium Hydroxide

(25% Aqueous solution)

Adjust pH to 4.0 15.00 15.00 15.00

Procedure

(1) Add Plasdone® K 29/32 to water-mix until totally dissolved.

(2) Add Stabileze® QM to water mix, then heat to 75°C. and mix until hydrolyzed.

(3) Cool to 60°C. add Suttocide® A.

(4) Add glycolic acid/NaOH.

(5) Add oil phase at 60° mix for 10 minutes.

(6) Homogenize 15 minutes.

(7) Cool to 40°, add preservative.

(8) Adjust for water loss.

EXAMPLE 4 A skin creme composition containing Plasdone® K-29/32 and 10% lactic acid was prepared as follows.

Water Phase Composition H₂0, deionized Plasdone® K 29/32 Stabileze® QM *(B₁₀/AC) Lactic acid

10% solids NaOH (25% aq) adjust pH to 4.0

* B₁₀/AC 28-35% lactic acid solids

Oil Phase

Ceraphyl® 65 1.0

Ceraphyl® 1CA 5.0

Ceraphyl® 368 5.0

Ceraphyl® 791 7.0

Cerasynt® 945 5.0

Cerasynt® 840 2.0

Germaben® 11 1.0

Procedure

Add Plasdone K 29/32 to water - mix until completely dissolved; then add Stabileze® QM mix well, heat to 75°C, forming a smooth, white mixture; cool to 60°C; add Suttocide® A and lactic acid, keeping temperature at 60°C; add oil phase at 60°C; mix for 10 minutes, homogenize 15 minutes, a thin water-like consistency; cool; add the neutralizer to bring pH to 4.0.

EXAMPLE 5 A skin care facial toner composition containing Plasdone® K 29/32 and 14% glycolic acid was prepared as described in Example 4 above. The compositions included:

% W/W Water, DI 68.64

Glycolic acid (70%) 14.29

Ceraphyl 60 0.5

Glycerine 5.0

Non-alcoholic witch hazel 10.0

Tetrasodium EDTA 0.05

FD & C Red (1.0% aq. sol.) 0.02

Germaben II 0.5

NaOH (10% solution)* * Adjust pH to 3.5

EXAMPLE 6 An after-sun gel composition containing a P(VP-VA) polymer and 3-5% lactic acid was prepared as follows:

Ingredients Water Phase %W/W

Water, deionized q.s. Propylene glycol and Diazolidinyl urea and methylparaben and propylparaben 1.00

Carbomer 980 2.00

P(VP-VA) S 630 1.00

Premix 3.80

Water deionized 3.0

Lactic Acid (88%) 3-5% Triethanolamine, 99% adjust pH to 4.0 OIL PHASE q.s.

Maleated soybean oil 27.0

Isocetyl alcohol 28.0

Dioctyl malate 28.5

Alpha-bisabolol 4.5

Microcrystalline wax 5.0 d-alpha tocopheryl acetate 3.5

Procedure

(1) At room temperature add ingredients of water phase in order listed. Mix until completely uniform between additions. Do not aerate.

(2) Add premix to water phase slowly. Do not aerate.

(3) Add lactic acid (88%) .

(4) At 85°C. add ingredients of the oil phase to separate vessel in order listed. Mix until uniform between additions.

(5) While in liquid form, add oil phase to water phase in desired design.

EXAMPLE 7 Facial Exfoliating Cream

Premix

Glycerin 3.00

Propylparaben 0.20

Methylparaben 0.20

Maleated soybean oil 3.00

Phenoxyethanol 0.50

Squalane 0.05

Fragrance 0.25

Jojoba wax (40/60) 3.00

Lactic Acid lo.oo

100.00%

Procedure

(1) Heat water to 85°C.

(2) Disperse hydroxyethylcellulose in water until clear and uniform. Add polymer.

(3) Add paraben premix.

(4) Heat oil phase to 85°C. and mix until uniform.

(5) Add oil phase to water phase. Mix well with sweep blade.

(6) Homogenize.

(7) Cool to 40°C. while mixing.

(8) Add remaining ingredients in order listed, mixing well between additions.

Acetamide ea and collagen a ino acids and silk amino acids and hydrolyzed elastin 0.10

Propylene glycol and kiwi fruit extract 0.25

Lecithin and superoxide dismutase 0.25

Aloe vera gel (10X concentration 0.02

Procedure

(1) Completely disperse Carbomer in water with heat to 85°C. Add PVP, then lactic acid.

(2) Add propylene glycol premix. Then TEA premix.

(3) Heat oil phase to 85°C. Mix until uniform.

(4) Add oil phase to water phase. Mix until uniform with a sweep blade.

(5) Homogenize.

(6) Cool to 45°C. while mixing with a sweep blade.

(7) Add imidazolidinyl urea premix. Mix until uniform.

(8) Add remaining ingredients in order listed. Mix well. Note: cream will become lustrous overnight.

(1) Heat Phase A with agitation to 85°C. , mix until uniform (40-45 minutes) .

(2) Lower temperature to 60°C. Add Phase B.

(3) Heat Phase C to 85°C, mix until uniform.

(4) Reduce heat to 60°C.

(5) Add Phase C to Phase A/B while homogenizing for approximately 5-10 minutes, being careful not to aerate the batch.

(6) Remove. Add Phase D using a sweep blade.

(7) Sweep to 25°C.

(8) Adjust pH to 3.5 with NaOH (10% aq.) EXAMPLE 10 Sunscreen Lotion with Escalol® Sunscreens INGREDIENTS

Phase A %w/W

Water, deionized 50.40

Xanthan Gum 1.00

Propylene glycol 6.00

PVP K-30 1.00

Lactic Acid (88%) 4-10%

Phase B

Glyceryl stearate and laureth-23 6.00

PEG-20 stearate 3.00

Cetyl lactate 3.00

C₁₂-C₁₅ alkyl lactate 1.00

Myristyl yristate 4.00

Octyl methoxycinnamate or octyl dimethyl PABA 7.50

Benzophenone-3 3.00

Octyl Salicylate 3.00

Premix

Titanium dioxide and aluminum hydroxide and stearic acid 5.00

Isocetyl stearoyl stearate 3.00

Maleated soybean oil 3.00

Phase C

Diazolidinyl urea and propylene glycol and methylparaben and propylparaben 1.00

Phase D

Fragrance (Pina Colada AL-60) 0.10 - 19 -

Procedure

(1) Prepare premix with roller mill.

(2) Disperse the gum cold and high speed mixing, then add propylene glycol and lactic acid. Heat to 75°C.

(3) Heat Phase B to 80°C. add premix.

(4) Add Phase B to Phase A, mix for approximately 10 minutes.

(5) Place under homogenizer and mix for approximately 15 minutes.

(6) Remove. Mix to 40°C. using sweep blade.

(7) Add Phase C, then add Phase D.

(8) Mix to 25°C. using sweep blade.

EXAMPLE 11 Body Lotion

INGREDIENTS Oil Phase % /W Glyceryl stearate 5.00 Octyl methoxycinnamate 7.50 Benzophenone-3 3.00 Octyl salicylate 3.00 Tridecyl neopentanoate 10.00 PEG-20 stearate 2.00

Water Phase Deionized water 56.00 Carbomer® 951 2.00 P(VP-VA) W 735 2.0% Lactic Acid 88% 3-15%

Preservative Premix 3.40 Propylene glycol 3.0 Methylparaben 0.2 Propylparaben 0.2 - 20 -

Triethanolamine Premix 3.30

Triethanolamine, 99% qs to pH 4.0 Deionized water 3.0

Imidazolidinyl urea premix 3.30

Imidazolidinyl urea 0.3

Deionized water 3.0

Lecithin and superoxide dismutase 0.05

Maleated soybean oil 3.00

Chamomile extract 0.05

Fragrance 0.20

Procedure

(1) Mix Carbomer and deionized water at 85°C. until uniform. Add lactic acid.

(2) Add preservative premix.

(3) Slowly add triethanolamine premix.

(4) In separate vessel mix oil phase until uniform at 85°C.

(5) Add oil phase to water phase slowly. Mix at 85°C. until uniform.

(6) Homogenize.

(7) Mix while cooling to 45°C.

(8) Add imidazolidinyl urea premix.

(9) Add remaining ingredients one at a time, stirring well between additions.

EXAMPLE 12 Example 7 was repeated except that glycolic acid was substituted for lactic acid.

EXAMPLE 13 Example 7 was repeated except that 1 g. of P(VP-VA)-630 was substituted for Ganex® P 904. EXAMPLE 14 Example 7 was repeated except that 5 g. of salicyclic acid was substituted for lactic acid.

EXAMPLE 15 Example 7 was repeated except that a mixture of 1 g. of PVP K-30 and 1 g. Ganex® P- 04 was used as the polymer.

EXAMPLE 16 Aqueous Gel Solution Composition Ingredients Wt. %

Water, deionized <I«s.

Lightly crosslinked PVP 0.50

Lactic acid (88%) 10

Glycerine 50

GERMALL® II (Sutton) 0.30

Procedure

1. Prepare a mixture of lightly crosslinked PVP in an aqueous solution with lactic acid (88%) with stirring for 10 minutes at 40-50°C. until thickening occurs.

2. Add glycerine slowly over 10 minutes with stirring. Stir until uniform gel is obtained.

3. Add remaining ingredients, mixing thoroughly after each addition.

EXAMPLE 17 Hydroalcoholic Gel Ingredients Ethanol

Water, deionized Lactic acid Glycerine

Lightly crosslinked PVP PVP K-30 Additives

Procedure

1. Prepare hydrogel by adding lightly crosslinked PVP in ethanol, water, glycerine, lactic acid, then heat to 40°-50°C. in suitable enclosed vessel with stirring for 15 minutes.

2. Start cooling.

3. Add remaining ingredients with stirring. Mix thoroughly after each addition, until uniform gel is obtained.

1. Prepare a spray gel by adding lightly crosslinked PVP in water, ethanol, lactic acid, and P(VP-VA) S-630 for 15 minutes, then heat to 45°C.-60°C. in suitable enclosed vessel with stirring for 30 minutes.

2. Start cooling.

3. Add remaining ingredients with stirring. Mix thoroughly after each addition, until uniform. Suggested Pump: - Cal ar Mistette, Mark II, 0.20 ml/stroke, yellow orifice (high viscosity) . EXAMPLE 19 Anti-Irritation Testing A comparative irritation test was conducted to determine the extent of reduction of irritation during use of a PVP-lactic acid composition. The results indicated that the addition of 3% PVP to 10% unneutralized lactic acid produced a significant reduction in irritation.

When applied to the face, a solution of unneutralized 10% lactic acid itself caused irritation of varying degrees in certain people while causing no discomfort in others. These sensitive individuals are used to compare the irritation caused by a 10% lactic acid solution to that caused by other test materials; in this case, a 10% lactic acid solution which contained 3% PVP.

In this study, a panel of 12 volunteers was selected from people who previously reported moderate stinging following application of the standard lactic acid solution. These people were asked to report their reactions to a control solution of lactic acid and to a test solution of 10% lactic acid with 3% PVP. Test materials were randomly applied with a cotton-tipped applicator to either the left or right naso-labial fold. Subjective reactions (on a scale of 0-3, with 0 being no irritation) were reported 10 seconds, 2 and a half minutes, and 5 minutes after application. Results are as follows:

Time after Application Number of persons responding 10 sec 2.5 in 5 min Lactic acid 7/12 9/12 8/12

Lactic acid and PVP K-30 3/12 4/12 2/12 Severity of response (sum of 1+, 2+ and 3+ reactions

Lactic acid 8 13 9

Lactic acid and PVP K-30 4 6 2

(total possible score 36) EXAMPLE 20 Example 19 was repeated except that P(VP-VA) S-630 (2%) was used. Similar results were obtained.

EXAMPLE 21 Example 19 was repeated except that Ganex® P-904 (3%) was used. Similar results were obtained.

EXAMPLE 22 ERYTHEMA REDUCTION TESTING A 10.0% glycolic acid (aq.) solution was tested against a solution of 10.0% glycolic with 1.0% Plasdone® K-29/32. Two drops of solutions were applied to the skin gently in a one-inch square area and allowed to air dry.

The readings were taken with a Dia-Stron Erythema Meter.

EXAMPLE 23 Example 22 was repeated except that Ganex P-904 (2%) was used. Similar results were obtained.

EXAMPLE 24 Example 22 was repeated except that lightly crosslinked PVP (0.5%) + PVP (1%) was used. Similar results were obtained.

Results:

SITE 2 SITE 3

Calculation: Before Treatment Minus After Treatment X 100%

Initial Reading

Conclusion: Polyvinylpyrrolidone acts as a counter-erythema agent in a low pH solution

EXAMPLE 25 Cell Renewal Studies

This study evaluated the disappearance of dansyl chloride (5-dimethylaminonaphalene-l-sulfonyl chloride) from the stratum corneum of treated and control sites. Such disappearance is accepted as a marker of the transit of cells through the horny layer, and thus a function of the rate of new cell production.

The composition comprised about 150 ml of each liquid, lotion, gel or cream.

The subjects consist of 26 females.

Method

The compositions and controls were tested on site areas on the outside of both upper arms which were thoroughly cleansed with 70% isopropyl alcohol. The number of test site areas were one greater than the number of test materials so that one site served as an untreated control site. The test sites were outlined with gentian violet surgical marker on Test Day One. Each test site measured 5 cm x 5 cm; a space of at least 2 cm being be left between test sites. The bottom of the lower test site was approximately 8 cm above the superior aspect of the elbow fold.

Approximately 0.8-1.0 g of the 5% dansyl chloride in petrolatum was spread evenly over a 2 cm x 2 cm area in the center of the previously outlined 5 cm x 5 cm test site. The number of dansyl chloride patched sites equaled one plus the number of test materials so that one site served as an untreated control site. The dansyl chloride patch site areas were kept dry and the patches in place for 24 hours. Then the patches were removed and excess dansyl chloride wiped off. The even penetration of the dansyl chloride was confirmed by examination for the even presence of fluorescence under ultraviolet illumination under a Wood's light (model SL- 3660 Long Wave Ultra Violet, Black Light Eastern Corp., Westbury, Long Island, New York) .

Each patch site area will be scored: Present (P) , Mottled (M) , or Absent (A) .

On a randomized basis, 50 ul of each test material was applied to a predesignated site. One site served as an untreated control site. The 50 ul of test material was dispensed within the 5 cm x 5 cm test site area and spread the product evenly within the test site area.

Test Materials Ratings for Appearance

A = Water Solution of PVP - Lactic Acid (1:10) 5 Uniform, very bright

B = Water Solution of Lactic Acid (10%) 4 Uniform, moderate brightness

C = Dansyl Chloride 5% (Control) 3 Faded, yet visible fluorescen

2 Faded, spotty appearance

1 Complete disappearance

EXAMPLE 26 Example 25 was repeated except that Ganex P-904 (2%) was used instead of PVP K-30. Similar results were obtained.

EXAMPLE 27 Example 25 was repeated except that P(VP-VA) S-630 (2%) was used instead of PVP K-30. Similar results were obtained.

In accordance with another feature of this invention, a process is provided for making a free- flowing powder of a complex of an alpha-hydroxy acid (AHA) and/or a beta-hydroxy acid (BHA) and a vinylpyrrolidone (PVP) polymer, copolymer or graft polymer, as the complexing agent, at high acid loadings, preferably 20-60% by weight. The presence of PVP in the complex reduces the skin irritation effect of the acid when applied to the skin of the user.

The process of the invention involves applying an aqueous solution or slurry of the acid to PVP, and, substantially immediately thereafter, evaporating the water to form a free-flowing powder of the complex of the acid and PVP.

A suitable alpha-hydroxy acid is lactic acid, glycolic acid, citric acid, tartaric acid, malic acid, pyruvic acid, azelaic acid and the like. Suitable beta- hydroxy acids include salicylic acid and the like.

Suitable vinylpyrrolidone-complexing agents include PVP itself, either in water-soluble form or in water-insoluble form (crosslinked) ; or copolymers thereof, e.g. with vinyl acetate or acrylic acid, or graft copolymers thereof, e.g. with C^Ca alkyl groups, e.g. butene, dodecene, hexadecene, etc. The process of the invention may be carried out in a fluid bed, by spray drying a solution or slurry, or by tray drying a slurry.

In accordance with one embodiment of the present invention, a fluidized bed containing a charge of PVP powders is reacted with an aqueous solution of concentrated AHA or BHA. The PVP polymer can be obtained from International Specialty Products in the form of a water-soluble or water-insoluble polymer, which has a molecular weight ranging from the K-15 to K-90 designations. These PVP polymers, which generally have a water content of about 5% by weight, or less, and a particle size of about 10 to 100 microns, may be used directly in the process of the invention, or pre-dried, if desired, to reduce its moisture content.

The AHA used herein usually contains about 20- 88% by weight acid.

The fluidized bed of PVP powders can be maintained in the fluidized condition by directing a current of dry air through the powders, by mechanical agitation of the powders, or by a combination of both techniques.

The fluidized bed is maintained at a suitable bed (reaction) temperature at which formation of the desired AHA-PVP complex product can occur readily without affecting the powdery state of the PVP polymer, and at which excess water from the acid solution can be quickly removed both from the product and the PVP bed itself. The selected bed temperature also will enhance the formation of a free-flowing powder rather than a gum. Such suitable reaction temperatures range from about ambient temperature to 90°C, preferably about 80°C.

The aqueous concentrated acid solution preferably is contacted with the PVP powders as finely divided droplets of liquid. Such desired droplets may be formed by pumping the aqueous solution through a spray nozzle and onto the PVP bed at a selected rate and for a predetermined period of time. Any spray nozzle capable of producing a fine dispersion of droplets may be used for this purpose. If necessary, however, a stream of air may be introduced into such nozzle with the solution to assist in atomizing the solution into finely divided droplets.

The spray solution of aqueous acid thus formed preferably is introduced into the fluidized bed of PVP powders at a selected rate such that excess water can be removed therein during formation of the complex without retaining free acid therein. A suitable feed rate for introduction of the acid solution is about 5-50 g/minute/kg PVP, preferably about 5-25 g/minute/kg PVP. Under these flow rate conditions, a free-flowing powder of the desired AHA-PVP complex is obtained containing about 20-60% by weight, preferably 25-50%, and about 2% or less water therein. The powder also may contain about 0.1-2% by weight of a flow enhancer, such as fumed silica, if desired.

In the preferred form of the process of the invention, the spray solution of acid is directed onto the PVP bed for a period sufficient to form a free- flowing powder having an acid content of about 25-50% by weight, which is indicative of a complex having a 1:1 molar ratio of PVP to acid. At this point in the process, the feed is discontinued to preclude excess water and/or free acid from forming on the free-flowing powder which can cause it to become gummy. The appearance of a gummy product is indicative of the presence of excess water and/or free acid in the product.

The spray solution of acid may be directed onto the fluidized bed as a vertical, horizontal or by downward flow of droplets. If a fluidizing air stream is used to create the fluid bed, it is usually directed upwardly against the PVP powders. Such air currents also can assist in carrying water away from the bed. The fluidized state of the bed also may be maintained using mechanical agitation, or a combination of both air and mechanical means.

The process of the invention can be carried out in one or two steps, i.e. removal of water from the product and bed can take place either (a) simultaneous with or after mixing of the reaction components in the same apparatus, or (b) in a downstream drying step, or (c) by a combination of both steps. The particular method of drying will depend upon the type of equipment used. For example, if a fluidized bed mixer is used, such as a plowshare, belt screw or paddle mixer, then the moist acid-PVP product can be dried further in a separate dryer. This sequence is characterized as a two-step process. Any suitable dryer can be used for this purpose, such as a vacuum, radiant heat or contact dryer.

Furthermore, if desired, application of the spray acid solution onto the PVP bed, followed by downstream drying, may be carried out in several stages in order to increase the acid content of the product towards the desired 3:1 to 1:1 molar ratio, and to reduce its water content.

Moreover, a fluid bed dryer may be used in the process which has the dual capabilities of providing both the fluidized bed and drying functions. Accordingly, drying of the product will begin and be completed during reaction between the PVP charge and the aqueous acid solution. Such a process may be considered as taking place in a one-step.

Preferably, reaction and dehydration are continued until the product reaches a desired acid content, suitably about 20-60% acid, and usually about 25-50%, with less than about 2.5% water, generally about 1%. However, it is essential that the product remain in the free-flowing state after completion of addition of the acid solution.

The size of the fluidized bed reactor, the rate of addition of the AHA or BHA solution, and the reaction times will vary with the particular equipment used, as well as the concentration of the acid solution and the reaction temperature, keeping in mind the purposes intended to be achieved with respect to each of these process parameters.

Alternatively, the process of the invention may be practiced by spray drying or tray drying, in the conventional manner known in the art.

However, it is believed that the following examples will illustrate the employment of these parameters to provide a process which can be used for the commercial production of the desired acid-PVP products. These examples, of course, are given by way of illustration only, and are not to be construed as limiting the invention.

EXAMPLE 28

An 88% aqueous solution of L-lactic acid was spray fed onto a UniGlatt fluid bed unit containing 300 g of PVP-CI (K-30 grade) supported on a 100-mesh dutch weave screen. A feed rate of about 1.1 cc/hr/g lactic acid was used at an inlet air temperature of 80°C. The product temperature was about 45°C. A 22% lactic acid loading was achieved in the complex, which was a free- flowing powder. The moisture level of the product was 1.85%. EXAMPLE 29

A crosslinked PVP (Polyplasdone XL) charge of 250 g and the concentrated (88%) lactic acid solution was used. A 28.8% loading at 1.2% moisture was achieved within 40 minutes of operation.

EXAMPLE 30

The procedure of Example 28 was repeated, however, after about 20 minutes, a fumed silica flow enhancer (Cabo-Sil) was added at about a 1% concentration. A 5 minutes dryout period achieved a 1.3% moisture with a final loading of 28.5% lactic acid.

EXAMPLE 31

The run was conducted with Ganex® P-904, a copolymer of 90 wt. % polyvinylpyrrolidone with 10% grafted butene. 150 g. of the graft polymer was charged to the unit. During the 50 minute run, the volume was reduced by about one-half of lactic acid feed. The copolymer loading of 32.5 wt. % was achieved.

EXAMPLE 32

A 50/50 blend of polyvinylpyrrolidone K-30 (PVP-CI) and crosslinked PVP (Polyplasdone® XL) was charged to the unit. A loading of 29.6% lactic acid was achieved. Then 1/2 of the product was withdrawn from the bowl and approximately 1/2% silica flow enhancer was added and the unit restarted. A final loading of 32.5% lactic acid was achieved after 55 minutes. EXAMPLE 33

Crosslinked PVP (Polyclar®) 50 g was added to a well-stirred solution of lactic acid (88%, 57 g) and water (135 ml) . After thorough mixing, the slurry was poured onto a tray and the slurry was dried under low vacuum at 50°C. The product was a free-flowing powder having a loading of 49.6% lactic acid.

EXAMPLE 34

Crosslinked PVP 20 g was added to a well- stirred solution of glycolic acid (70%, 29 g) and water (60 ml) After thorough mixing, the slurry was poured onto a tray and dried under low vacuum at 50°C. The product was a free-flowing powder with 48.6% glycolic acid.

EXAMPLE 35

Example 32 was repeated except the drying process was spray drying. Similar results were obtained.

EXAMPLE 36

Example 33 was repeated except the drying process was spray drying. Similar results were obtained.

EXAMPLE 37

Example 33 was repeated except that glycolic acid (70% aqueous solution, 29 g) was used. The product was a free-flowing powder having a loading of 48.6% glycolic acid.

Claims

WHAT IS CLAIMED IS:

1. A cosmetic composition comprising an alpha or beta-hydroxy acid, or mixtures thereof for treatment of skin problems with only minimal skin irritation for the user and a vinylpyrrolidone-co plexing agent.

2. A composition according to claim 1 which includes a solvent which is water or an organic compound, or mixtures thereof.

3. A composition according to claim 1 wherein the alpha-hydroxy acid is lactic acid or glycolic acid, and the beta-hydroxy acid is salicylic acid, or mixtures thereof.

4. A composition according to claim 1 wherein the vinylpyrrolidone-complexing agent is polyvinylpyrrolidone.

5. A composition according to claim 1 wherein the organic compound is ethyl acetate, and contains about 1-10% by weight acid and 1-10% by weight PVP.

6. A composition according to claim 1 in the form of a powder.

7. A cosmetic composition for rejuvenating the appearance of skin with substantially no skin irritation, in the form of a lotion, creme, solution or gel, comprising an aqueous, alcoholic or aqueous-alcoholic solution of a hydroxy acid, and a substantially colorless vinylpyrrolidone-based polymer, copolymer, graft polymer or lightly crosslinked polymer, and mixtures thereof, as anti-irritation, and anti-erythema agent therefor, said composition having a pH of about 1.5 to about 5.0, the weight ratio of polymer to hydroxy acid being about 1:1 to about 1:20.

8. A cosmetic composition according to claim 7 which contains about 0.5-10% by weight vinylpyrrolidone- based polymer, copolymer, graft polymer or lightly crosslinked polymer.

9. A process for the production of alpha or beta-hydroxy acid-vinylpyrrolidone (PVP) polymer, copolymer or graft polymer complexes in the form of free- flowing powders which comprises applying an aqueous solution or slurry of said acid to said PVP polymer, copolymer or graft polymer, substantially immediately thereafter, evaporating the water to form a free-flowing powder of the complex of the acid and said PVP polymer, copolymer or graft polymer.

10. A process according to claim 9 which comprises reacting a fluidized bed of PVP maintained at a reaction temperature of about ambient temperature to about 95°C. with finely divided droplets of a 20% to 88% by weight aqueous solution of said acid, and drying the product.

11. A process according to claim 10 wherein the acid feed rate is about 5-50 g/min/kg PVP.