AP789A - Skin care compositions containing retinoids and liposomes. - Google Patents

Abstract

The invention relates to a skin care composition comprising B. nan—phospholipid liposome and a retinoid selected from the group consisting of retinal, retinal, retinyl acetate, retinyl paImitate and mixtures thereof, the composition further comprising. a stabilizing system selected from the group consisting of : a) an oil soluble antioxidant; and b) a chelating agent and at least one oil—soluble antioxidant; wherein the composition has a pH from at least about 5 to about 10, and the composition retains at least SOX of said retinoids after 13 weeks' storage at 50'C. The composition is useful in treating various skin problems such as photoaging and sun damage,

Description

SKIN CARE COMPOSITIONS CONTAINING RETINOIDS AND LIPOSOMES

HELD OF THE INVENTION

This invention relates to skin care compositions containing retinoids wnich generally imorove the auaiity ot the skin, oanicuiarlv human facial skin. More particularly, me present invention relates to cnemically stable skin care compositions containing a non-pnosonoiiDib liDOSome formulation ano certain retinoics.

BACKGROUND OP THE INVENTION

Skin care compositions containing retinoids have become the focus of 10 πγβατ inTeresT m recem vears. Retinnir ^r-iri -Ivn Unnwn Vitamin Δ aniH

acne and prooucts containing retinoic acio are commercially available in various forms. Sucn prooucts, for example, include Retin A* creams, an oil-in-water emulsion of retinoic acid containing an oii-solubie antioxidant, 15 butylated hyaroxytoiuene (BHT); Retin A* liquid, commercially available from Ortho Pharmaceutical Corporation of Raritan, New Jersey, which is a solution of retinoic acid in a poiyetnvlene glycol/ethanoi solvent employing EHT as an antioxidant; and Retin A* gel, which comprises retinoic acid in a gei vehicle comprising ethyl alcohol as the solvent, 20 hydroxypropyi cellulose as the thickener or geiiing agent and BHT as an antioxidant.

_Ap 00789

- 2 These retinoic acid containing products have Droven stable ana capable of providing acrive ingredients after extenaea periods of storage. More recently, however, wider use of retinoids has been suggested for treatments other than acne such as, for exampie, the treatment of skin against photoaging ano sun damage. Many individuals who have had a good deai of sun exposure in childhood will show the following gross cutaneous alterations in later adult life; wrinkling, ieatheriness, yellowing, looseness, rouanness. dryness, mottling (hyperpigmentation) and various premaiianant growths (often subclinical). These changes are most prominent in light-SKinnea persons who burn easily and tan poorly. These cumulative effects of sunlight are often referred to as photoaging. Althougn the anatomical degradation of the skin is most advanced in the elderly, the destructive effects of excessive sun exposure are already evident by the second decade. Serious microscopic alterations of the epidermis and dermis occur decades before these become ciinicaily visible. Wrinkling, yellowing, ieatheriness and loss of elasticity are very late changes.

U.S. Patent No. 4,603,146 suggests the use of Vitamin A acid in an emollient vehicle es a treatment for ameliorating the effects of photocamage. Further, U.S. Patent No. 4,877,805, suggests that a numoer of retinoids are useful for restoring and reversing sun damage of human skin.

Certain retinoids sucn as, for exampie. retinol (Vitamin A alcohol), retina (Vitamin A aldehvoel and retinyl esters such as retinyi acetate and ratiny palmitate may be preferaole to use in skin care compositions as opposes to retinoic acid. Retinoi is an endogenous comoound r-.sturail' occurring in tne human body and essential for good growth

Ap .00789 λ / rs differentiation of epithelial tissues ana reoroauction. Retinoi is also preferred because it is safer ano less irritating to the skin than other retinoids, suer, as retinoic acio. Additionally, excess retinol is stored in the human booy largely in an inactive ester form, e.g. retinyi paimitate and, to some extent, retinyi acetate. The aldehyde, retinal, also a preferred

C form, is an active metaooiite of retinol and is needed for visual function. _v r

C

Accordingly, attention has turned toward formulating skin care compositions wnicn contain tnese oreferrea, naturally occurring retinoids h 10 which have simiiar Drooerties to existing retinoic acid formulations, i.e., providing a comoosition wnicn .is aestneticaily pteasina ana which can deliver active inareaients after a suostannal shelf life.

Typically, existing formulations containing retinoids are oil-in-water 15 emulsions in which the retinoic acid is carried within the oil phase and is protected from oxidation by employing an oil-soluble antioxidant. OII-inwater emulsions are generally considerea preferable to water-in-oil emulsions oecause they are nonocciusive, non-greasy, compatible with other sucn emulsion proaucts. easy to remove from the skin and are regarded as more aestneticallv pleasing as weii as being more economical to manufacture. Generally, the cnemicai stability of the active retinoic acid ingreaient is auite good in that the oil phase protects the retinoic acid, especially when an oit-sotubte antioxidant is present. Thus, for examoie, the aforementionea Retin A* cream is an oii-in-water emulsion containing retinoic acid and BHT, an oii-soiubie antioxidant. In U.S. Patent 3.205,108 tnere is cisclosea an oil-in-water emulsion of retinoic acid wnicn may induce an oil-soluble antioxidant such as BHT or di-o-tocopneroi ano a cr. a. at. ng agen^-

e.g.ethvieneaiammetetraacetic acid (EDTA). In U.S. Patent 4,466.805,

AP. 0 0 7 8 9

- 4 a tanning comoosition is descnbea which may include,among other ingredients Vitamin A in an oii-in-water emuision containing Vitamin E and citric acid.. In U.S. Patent 4.247,247 still another form of a retinoic acid containing comoosition, namely a gel, is disclosed and is protected by an antioxidant selected from the group consisting of butylated hydroxytoiuene. butylated hydroxyanisote (BHA) , ascorbic acid (Vitamin C) , proDyi gallate, and κ-tocoonerol (Vitamin Ei.

A number of skin care proaucts have appeared in the marketplace incorporating otner retinoios. including, for examoie, retinol, retinal and *r retinyl esters sucn as retinyl acetate and retinyl palmitate. Unsurprisingly, these comoositions emulate the formulas of commercial retinoic acid compositions: they are oii-in-water emulsions protected by oii-soiubie antioxidants. However, for reasons not yet clearly 15 understood, the retinoids other tnan retinoic acid in such compositions quickly lose their activity and either oxidize or isomerize to non-efficacious chemical forms with the result that the amount of retinoid actually available to provide the peneficiai effects of the product is reduced, in an unacceotaniy snort perioa of time, to an ineffective quantity and eventually 20 only to trace Quantities.

Generally tnen, products containing retinoids have been limited to oii-inwater emulsions and. with respect to those other than retinoic acid, have suffered from chemical instability. In a few instances, however, products and/or suggestions for products have been made wherein retinoids such as retinol, retinyi acetate and retinyl paimitate are formulatc-p in water-in-oii emulsions.

Λ Π/DV Q 7 ftp . 0 0 7 8 9

- 5 Thus, for example,. in U.S. Patent 4,82B.S2B aescribes a stable comoosition ccmorisina retinol, retinyi acetate and retinyi palmitate may consist of retinol in a water-in-oii emulsion wherein the emulsion further include two oii-soiuble antioxidants, EHT and BHA.

Further, Avon Proaucts, Inc., the assignee of U.S. 4,825,828, seiis two skin care proaucts called Bioaavance and Bioaavance 2000. Each of these products is supplied in two Potties, portions of which are mixed together just prior to use. The first dottle contains what is caiied a skin lotion, while the second bottle contains what is caiiea a fortifier. The skin lotion” is a water-in-oii emulsion having a number of ingredients which inctude water, emulsifiers, silicone and vegetable oils, preservatives.

• emollients and butylated hydroxytoluene (BHT) The fortifier is a nonaqueous solution which contains a number of ingredients including cyciomethicone (a siiicone oil), denatured ethanol, an emulsifier (Polysorbate 20), retinol, retinyi acetate, retinyi palmitate, BHT and BHA. When a specifiea portion of tne fortifier is added to a specified portion of the skin lotion ana mixeo, there results a water-in-oii emulsion which comprises retinol, retinvt acetate, retinyi palmitate. BHT and BHA, the latter being oii-soiubie antioxidants. The outer package in which Bioaavance is supplied carries a statement which says Because BIOADVANCE begins to lose effectiveness after one month, for maximum benefits, use a fresh supply each montn. It would appear from this statement that the chemical staoility of the retinoids in the mixture of the skin lotion and the fortifier is quite limitea. The fact that in .both the BIO ADVANCE and BIOADVANCE 2000 products the fortifier ingredients must be mixed with the skin lotion ingredients immeciateiy prior to use indicates that the resulting water-in-oii emulsion which is applieo to the skin also has p/p/ 9 7/01101

AP.00789

- 6 limited chemicai staoiiity of one or more of the above-mentionea retinol, retiny! acetate ana retinyi palmitate.

Furtner still, U.S. 4,720.353 to Sell describes water-in-oil emulsion carriers for various meaicaments and drugs intenaed for topical application to the skin. Water soluble, miscible or dispersible drugs may be incorporated into the aqueous phase of the emulsion. Oil-sotubie. miscible or dispersible drugs may be mcorporateb into the oil phase. Drugs which may be incorporated into tne emulsion include derivatives of retinoic acid. Ingredients which may ODtionaily be added to the emulsion .include a c preservative such as metnyi paracen, propyl paraben or imidazoiidinyl urea or an antioxioant sucn as Putytated hyaroxyamsoie and a water or- oil £ soluble vitamin such as vitamin C, tocopheroi iinoieate and the like.

• r c

Still further, EF 0 343 44-4 A2 . to Sterner et al discloses cosmetic preparations based on retinyi palmitate. Example 3 discloses a night cream in the form of an water-in-oii type emulsion comprising retinyi paimitate and butytatea hyaroxyamsoie (BHA). Example 4 discloses a water-in-oii emulsion comprising retinyi acetate ano a-Tocopneroi (Vitamin Ei.

I iii

Still funner, EP 0 330 496 A2 to Batt is directed to skin treatment compositions comorising a topically acceptable base and an effective amount of at least one ester of retinol, said compositions being useful in the treatment of pnotoagea skin. Example 6 discloses a water-in-oil emulsion comprising Vitamin A propionate and BHT, an oil soluble antioxidant.

Unfortunately, none of these Drior attempts to emulate tne stability cf the retinoic acid containing comDositions nave been successful for retinoids

AP .00789 other man retinoic acia ana in eacr. case result in substantial and unacceotaDie enemies! instaDiiity of the retinoi, retinal or retinoic esters empiovea therein. Accordingly, mere is a need for a composition in which sucn non-rennoic acid retinoids may be provided in a chemically stable form.

Jonas C.T. Wang, et.al in pending application USSN 719,754 filled Novemoer 15, 1993 disclose the stabilization of retinoi in a water-in-oil emulsion, in wnich retinol was dispersed and protected in oii phase. However, oii-in-water emulsions are mucn more preferred than water-in-oil emulsions Dasea on tne cosmetic performance. This is due to the fact that oii-in-water emulsions, in general, are less occlusive, less greasy, compatible with maxe-uD and easy to be removed from the skin leading to a more aesthetically pleasing feel. In addition, oii-in-water formulations are less costly considering the ingredient composition and the manufacturing process.

at

It is tnerefore aesiraoie to aeveiop efficacious ana also cosmeticaiiy elegant skin care proaucts containing retinoias including retinoic acid, retinal, retinoi, and retinyi esters to ennance the Droaa usage of retinol for skin treatment.

It is another object of this invention to provide skin care compositions containing retinoids wnich have acceDtaole shelf-lives.

It is yet anotner ooiect of this invention to pTovide a skir. care comnosition containing retinoids, which permits the controlled release of active ingreaients to the sxin over time.

AP.00789

- 8 Anotner object of this invention is to proviae a metnoa for making a stable skin care ccmoosition containing retinoios, which retains its activity over a long time ceriod.

it is yet anotner object of this invention to provide skin care compositions which are relatively non-irritating and yet efficacious in delivering active ingredient to the skin.

Other objects of this invention will become clear throughout the aescription

TO provided, below.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph depicting'the effect of pH on stability of retinol in nan15 phaspnoidid liposome formulations.

Figure 2 is a grapn depicting the amount of retinol released from the formulation of Example 8C comoareo with that of a water-in-oil formulation.

Figure 3 is a grapn depicting tne amount of active ingredient which permeates tne eDidermis ano dermis from the formulations of Examples 8C and 6 in comparison with that of a water-in-oii formulation.

Figure a is a graph depicting the sensory perceptions of certain formulations of this invention in comparison with otner skin care comoositions.

- 9 SUMMARY OF THE INVENTION

In accordance with The present invention, it has now been discovered Thai, unexpectebiv, certain retinoids may be successfully stabiiizeo against chemical degradation by incorporating them into- non-phosphoiipid liposomes using a specifically defined stabilizing system and process. The retinoids which can be stabiiizea against chemical degradation in accordance with the principles cf the present invention include retinol (Vitamin A alcohol) , retinal (Vitamin A aldehyae), retinyl acetate, retinyl

TO palmitate ana mixtures thereof. c

X

X

As used herein, the chemical stability or stability of a retinoid is _c defined in terms of the percentaoe of the specified retinoid which is h

retained in its original chemical form after the composition has been stored for a specified period of time at a specified temperature. Thus, if the original concentration of ail-trans retinol in an absolute ethanol solution were 0.20% by weight and. after two (2) weeks storage at room *· temperature (2VC = 1*0, the concentration of all-trans retinol were 0.18% by weight, then the original solution of all-trans retinol in absolute ethanol would be characterized as having a chemical stability of retinol of 90% after two weeks storage at room temperature. In the same fashion, if an non-phospholipid liposome formulation comprising all-trans retinol had an initial concentration of 0.30% by weight and after storage for 13 weeks at 50*C had a concentration of all trans-retinol of 0.24% by weight, then 25 the original emulsion would be characterized as having a chemical stability of retinol of 80% after 13 weeks storage -at 50*C.

For the specific retinoids wnich are the subject of this invention the nonphospnoiiDid liposome form, in comoination with the selection of a stability

AP.00789

- 10 · system from those aescnbea herein, wiil produce compositions having a chemical stability of 80% atter 13 weexs' storage at 50 *C. The present invention also provides a system for stabilizing retinoids, unexpectedly, without the presence of a water-soluble antioxidant.

Accordingly there is provided, in accordance with the teachings of the present invention, a skin care composition comprising a non-phospholipid liposome and a retinoid selected from the group consisting of retinoi, retinal, retinyi acetate, retinyi palmitate and mixtures thereof, said comoosition furtner comorising a stabilizing system selected from the grouo consisting of:

a) an oii-soiuble antioxidant; and

b) a chelating agent and at least one oii-soiuble antioxidant;

wherein said composition has a pH from at least about 5 to about 10, said composition retaining at least about 80% of said retinoids after 13 weeks storage at 50' C.

it was also discovereo unexpectedly tnatthe compositions of this invention can be endowed with material changes resulting in a controiied-reiease oi active agent from the iiposome carrier. The compositions of this inventior may also be moderated in order to ennance or diminish penetration of the active ingredient into the skin.

Surprisingly, compositions of the present invention cont.T^rny a reiativel' high levei of surfactants (e.g., > 8%) exhibit irritation at the same level a that experienced bv individuals exooseo to a water-in-υιι cream cc; tainin 2% surfactant.

AP.00789

- π DETAILED DESCRIPTION OF THE INVENTION

As describea sb.ove. me comDosition of the invention is in tne form of a particular type cf lioosome, namely, a non-pnospnotioio liposome.

Most commercial skin care comoositions such as the ones containing retinoic acid are oii-in-water emulsion systems. In such oil-in-water emulsion systems, certain retinoia compounds, in particular, retinol, retinal, and the retinyi esters tend to be chemically unstable, i.e. they degrade, _T either by way of oxidation or isomerization, and are, therefore, not ^c

V availabte to perform in their desirea manner. While this is not clearty understood, it is oelieved that this degradation occurs as a result of the £ rapid diffusion of oxygen through the external water phase to the internal oil phase containing the retinoid. The oxygen is readily available to degrade c the retinoid. Because the diffusion of oxygen is greater in a water phase £ than an oil phase, an oii-in-water system is more prone to such£i degradation.

The compositions of the present invention overcome these difficulties and instead, provide a non-phosohoiipid liposome comDosition containing at least one retinoid comoound wherein ooth the physical stability of the liposome ana the cnemical stability of the active ingredients are maintained at high levels.

Liposomes are spnerical, self-closea structures composed of curved lipid biiayers which entrap pan of the solvent, in wnicn the·,· ueeiy float, into their interior. They may consist of one or severai concentric membranes. Liposomes are maae predominantly from amphipniles. ό special class of surface active moiecuies. which are cnaracterizea by having a hydrophilic

AP . Ο Ο 7 8 9

-12ana a hyaroonooic grouD on the same moiecuie. These molecules are nor soluble in water: ana, rawer than forming solutions, they form colloidal disoersions.

Until recently, liposome technology has been concerned mostly with vesicles composea of phospholipid. Phospnotipids are labile and expensive to purify or synthesize. In addition, manufacture of phospholipid liposome is difficult and costly to scale up. For these reasons there has been wr increasing interest in non-pnosonolipid liposomes. Certain double-chain c «Γ synthetic surfactants with non-ionic polar heaas and single-chain surfactants in mixture with cnotesteroi can form non-ionic liposome. They c have increased cnemicat stability over natural phospholipid and are easy to ¹ r make in large, commercial quantities. , i

Because of their solubility properties the structure of these aggregates j invotves the ordering of lipid molecules: the hydrophilic part tends to be in ' contact with water while the hydropnobic hydrocarbon chains prefer to be hidden from water in the interior of the structures. One of the most frequently encountered aggregate structures is a lipid bilayer. On the surface of either side are poiar heaos which snieid non-poiar tails in the interior of the ismeila from water. At higher lipid concentrations these bilayers from lamellar crystalline phases where two-dimensional planar lipid bilayers alternate with water layers. Upon dilution, these iipid bilayers form liposomes. These liposomes can entrap nyaropniiic materials in the aqueous compartments ano lipophilic materials in the biiayers. Molecules that are entrapped in the bilayers are sometimes referred to as cargo molecules. Lipophilic entrapment is severely limited by the ability of the bilayer to entrap the cargo moiecuie.

A Ρ .00789

- 13 Liposomes can ce large or smail and may be comDosea of from one to several hunareo concentric bilayers. With respect to the size and the number of lamellae, they are distinguished as large multilameiiar vesicles (MLV's) and large and small uniiameilar vesicles (LUV's and SUV's respectively). Most of the researcn to date have centered on above mentioned type of vesicles.

Recently, Donaid F.H Wallacn (U.S. Patent number 4,911,228) described another type of lipid vesicies, the paucitameilar lipid vesicies (PLV). The c invention describes the PLV's consisting of 2 to 8 peripheral bilayer surrounding a large unstructured central cavity which can be filled wholly or in part with an aooiar oil or wax. The multiple lipid bilayer and an apolar core of the PLV'S provide PLV'S with the capacity to transport a greater amount of lipopnilic materials.

Still further, U.S. 5,147,723 to Donaid F. H. Wallacn describes the nonphospholipid surfactants which can form pauciiameiiar lipid vesicies. The surfactant can ce selected from a group consisting of polyoxyethylene fatty esters having the formula R.,-COO(C,H_aO)_nH wnere R, is a radical of lauric. myristic. cetyl, stearic or oteic acid ana n is an integer from 2 to 10; polyoxyetnylene fatty acid etners. having the formuia Rj-COlC^HtQlJH where R_:is a radical of lauric, myristic, or cetyl acids, single or double unstaurateo octadecyi acids, or double unsaturated eicodienic acids and m is an integer from 2 to 4; polyoxyethylene (20) sorbitan mono- or trioleate; and polyoxyethylene glyceryl monostearate with from 1 to 10 poiyoxyetnyiene grouos.

All these structures have many interesting physic- cod chemical properties, sues as osmotic activity, permeaoility of their memcranes to

ΔΡ/Ρ/ Q 7 / n

AP.00789

- 14 different soiutes, solubilizing power, interaction with various hydrophobic and hydrooniiic soiutes. or aggregation benavior which can depend on temperature, chemical composition and surface characteristics of the membrane, and presence of various agents.

The oii-soiuble antioxidants which are useful in the compositions of the present invention include butylated hydroxytoluene (BHT), ascorbyi palmitate, butylated hyoroxyanisole (BHA), a-tocopheroi, phenyia-naphthylamine, hydroquinone, propyl gallate, nordihydroguiaretic acid, and mixtures thereof as well as any other known oil-sotubie _c antioxidant comoatible with the otner components of the compositions. ⁵ c

The oil-soluble antioxidants useful in the compositions of this invention · should be utilized in· a stabilizing effective amount and may range ^f in total from about 0.001 to.· about 5% based on the weight of the total composition, preferaoly from about 0.01 to about 1%. The* amount of antioxidants utilizeo in the compositions of the present t invention is dependent in part on the specific antioxidants selected, the amount of and specific retinoid being protected and the processing conditions. For example, a retinol formulation should include BHT in the amount of from about 0.01% to about 1% by weight. A retinal formulation should include BHT in the amount of from about 0.01% to about 1% by weight.

In certain aspects of this invention, the compositions may include a chelating agent during the scaie-up process to ir.'Uimize metal ion contamination. The retinoid compounds of this invention are sensitive to metal ions and in particular to bi- and tn-vaiem cations and in certain instances, appear aegraae rapidly in their presence. The

AP.00789

- 15 chelating agent forms a comDiex with the metai ions thereby inactivating mem ano preventing mem from affecting the retinoid comoounas. Cheiating agents wnicn are useful in tne compositions of the present invention mciuae ethYieneaiamine tetraacetic acid (EDTA) and derivatives ana saits tnereof, dihyaroxyetnyl glycine, citric acid, tartaric acid, ano mixtures tnereof. The cneiatina agents should be utilized in a staDiiizina effective amount and may range from about 0.01 to about 2% based on me weight of the total composition, preferaDly from about 0.05 to about 1 %.

t—

The retinoid comoounas wnicn are useful in me compositions of the . T— present invention consist of Vitamin A aicohol (retinol) , Vitamin A ,aldehyae (retinai) and Vitamin A esters (retinyl acetate and retinyi palmitate!. These retinoids are utilized in the compositions of the present invention in a therapeutically effective amount that may range from about cr 0.001 to about 5% by weight of the total compositions, preferably from about 0.001 co about 1 %.

The skin care comoosmons of the present invention comprising a non20 phosDnoiioio can be in the format of cream or lotion formulations, as desired, by varying the relative quantities of the lipid and water phases of the emuision. The pH of the compositions should be in the range of from at ieast aoout 5 to aooux 9, ana preferaoly from about 5 to about 7.

Any of the many formulations or compositions of the cream or lotion type currently utilizea in skin care preoarations can be employed provided that it is in a non-phosDnoliDid ana is chemically compatible with the retinoid comoounas. The ratio of the oii pnase of the mn-phospnoiipid liDosome to the waxer onase can ds from aoout 5:95 to about 40:60. The actual ratio

AP . 0 0 7 8 9

- 16 of the two onsses wiil deoeno on tne desired final product.

The advantages of the invention ano specific emoodiments of the skin care compositions prepared in accordance with the present invention, as weil as comparisons with compositions outside the scope of the claimed invention are illustrated by tne following examples. It will be understood, however, that the invention is not confinea to the SDecific limitations set forth in the inoividual examples, but rather to the scope of the appended claims. <

COMPARISON EXAMPLE 1 , Three oii-in-water emulsions of retinol (Vitamin A alcohol) were prepared t _ _ having the % w/w compositions set forth in Table 1. In Table 1, the appellation o/w indicates an oihin-water composition. These emulsions were prepared according to the following procedure. The ingredients shown under the heading Aqueous Phase ingredients were added to a first glass container eauippea with a stainless steel stirrer and heated with stirring to 75 ~ C-35 0 unaer an argon gas blanket. The ingredients shown under the heaoing Oil Phase Ingredients were added to a second glass container eauippea with a stainless steel stirrer and heated with stirring to about from 85*0 to 20 *C under an argon gas blanket. The ingredients shown under tne heading Retinoid Mixture were added to a third glass container equippea with a stainless steel stirrer and stirred at room temperature under a blanket of argon gas. Stirring was continued in ail instances until uniformity was achieved. The Aqueous P^asa ingredients at 75 * C-35 C were then added to the Oil Phase Ingredients. During this addition step, the Oil Phase Ingreoients were maintained at 55'5-30*0 with stirring unaer an argon gas blanket. The mixture of tne Aqueous

AP.00789

- 17 Phase Ingredients and Oil Phase Ingredients was stirred, at a temperature in the range of SO’ C and under tne argon gas blanket until a uniform oil-inwater emulsion was obtainea. After the resulting emuision was cooled to about 5O’C-53’C, the Retinoid Mixture was added with stirring. The emulsion was blanketed under argon gas and the temperature was maintained at about 50’0-53’C during the addition of the Retinoid Mixture. After tne addition ot the Retinoid Mixture was completed, the emulsion was gradually cooled, with stirring and under an argon blanket, to room temperature (approximately 21 ”Ck The finishea emulsion was

TO then transferred unoer argon gas blanketing to blind end aluminum tubes (2 ounce size) whicn were oromptiy crimoed and tightly capped. The closed tubes were tnen set aside for determination of retinol stability after storage for various time periods at various temperatures. Retinol degrades under the influence of UV light. Accordingly, care must be taken at all stages of the emulsion preparation process to protect the retinol from exposure to UV light. This can be accomplished by turning out the lights in the processing area or by conducting the various handling and processing steps under yellow light.

TABLE 1

Sampie Designation A B C

AP/P/ 9 7/01 101

Water, o.s 100%	—		- I
Propylene Glvcoi	4.00	4.GO	4.00
Carbomer 934	0.50	0.50	0.50

AP. Ο Ο 7 8 9

Qfl Phase Ingredients

	Mixture A I	8.75	8.75	8.75 j
	PoivsorbatB 61 (Tween 611	1.20	1.20	1.25 I
5	Dlmetniccne	1.00	1.00	1.00 I
	Soroitan Stearate	O.SO	0.80	0.80

Ffatingid Mixture

10 L	Ascorbic Acid	0.00	o.oo |	o.io
I	EDTA '	o.oo I	0.10	0.10
	Benrvl Alcohol	0.30 I	0.30	0.30
	50% NaOH. u.s. oM A.7	—	—	—
	Methvl Paraoen	0.15	0.15	0.15
15	Praovl Paraoen	0.10	0.10	Q.10
	Butyl Paraoen	| 0.05	o.os	Q.05
	BHT	0.02	1 0.02	ί α.02
	Fragrance	I 0.25	1 0.25	1 0.25
	| Retinol (all tran3l. USP	1.00	0.85	1 0.26
20	I Emulsion Type	1 O/w	) o/w	1 o/w

v

C ·>«, r>

a &

£

In the eaove Table 1, the ingredient in tne Uil Phase ingredients designated □a Mixture A consisted of 1.50 Q mvnstyt myristate; 1.25 g oleic acid (Emersol 2231; 1,25g glyceryl stearate IEmerest 24001; 1.25 g stearic acid (Emersot 1321; 1.00 g isoorooyi palmitate: 1.00 stearcxYtnmethylsilana (Dow Corning 520 Waxl; 0.50 synthetic beeswax: 0.50 g sTearvt aicahot: and 0.50 c cstvi aiconol. Mixture A was oreoared by mixing tne indicated ingredients in s glass container, stirring witn heat unvi <nl inurements were ?! tp:

J . ι U ι L

JL2

AP.00789

- 13 liquefied ana uniformly mixea; pouring me nauefiea mixture into shallow containers; ana allowing the mixture to cooi to amoient temperature.

Concentrations of all-trans retinol in oii-in-water samples A, B and C in Table 1 were determinea after storage for various time periods at various temperatures. Concentrations of retinol ana other retinoids such as retinal (vitamin A aldehyde), retinyi acetate and retinyi paimitate can be determinea by any suitable analytical procedure. As reported herein, we determined retinoid concentrations by a stability indicating high performance liquid chromatography (HPLC) procedure in which the chromatocraDn was eauippea with a reversed phase 5 micron C-8 column (25 cm in lenctn x 4.6 mm in diameteri anc a UV detector at 340nm. The sample to be anaiyzea was diluted with a solution of 50% by weight methanol and 50% by weight ethyl acetate to a concentration of 18 micragrams/'mi and the retinoid was detected at 340nm. The gradient mobile phase consisted of an organic portion composed of 5 percent tetrahydrofuran in acetonitrile and an aqueous portion consisting of 0.05N ammonium acetate. The solvent program has an initial composition of 70% organic/20% aaueous which increases linearly to 80% organic/20% aqueous at 1 3 manures, then again increases linearly to 100% organic at 15 minutes, where it stays until 19 minutes. After injecting 15 microliters of sample solution into the chromatograph, the analytical conditions were run at a flow rate of 2 mi/min and thermostatically reguiatea at 40*C. The retention time of retinol (Vitamin A alcohol) is about 6.4 minutes. The retention times of reTinal (Vitamin A atdehyae). 'etinyi acetate, and retinyi palmitate are uooui 7.5 mins., 10.1 mins, ana 18.7 mins. , respectively. The HPLC results were a:

AP. Ο Ο 7 8 9

- 20 · fauna to oe 'eproaucibie to better tnan s 3% range of standard deviation.

The resuits were ss follows:

For Samoie A: After twenty-six (26) weeks aging at room temperature (21 * C = 10*0, only 39% of the original amount of alltrans retinoi was found in the emulsion. After twenty-six (26) weeks , aging at ao*C, oniv three percent (3%) of the original amount of ⁽ all-trans retinoi was ‘ouna in the emuision.lt is concluded that an oii-in-water emulsion comprising retinoi and butylatea hyaroxytciuene (EHT), an oil-soluble antioxidant, does not have acceptable retinol chemical stability.

For Samoie B: After thirteen (13) weeks aging at room temperature, 87% of the original amount of all-trans retinol was found in the emulsion. After thirteen (13) weeks aging at 40'C, just four percent (4%) of the original amount of all-trans retinoi was found in the emulsion. After tnirteen (13) weexs aging at 50*C, no amount of all20 trans-retinoic acid was detected in Sample B. After twenty-six (25) weeks aging at room temperature, fifty-seven percent (57,%) of the original amount of all-trans retinol was found in the emulsion. It is concluded that chemical stability of all-trans retinol in an oil-in-water

AP.00789

- 21 emuision comorising aii-frans retinoi, EHT ana aisooium EDTA (a cheiating agent) does not nave acceotaole cnemicai stability.

For Samoie C: After tnirteen (13) weeks aging at room temperature, sixty 5 percent (60%) of the initial amount of all-trans retinoi was found in the emulsion, while after tnirteen (13) weeks aging at 40’C, twenty-three percent (23%) all-trans retinol was detected. No amount of all transretinol was cetectea after Sample C was stored for thirteen (13) weeks at

5O*C.

After twenty-six (25) weexs aging at room temperature, forty-two percent (42%) of the initial amount of all-trans retinol was found in Sample C; after fifty-two (52) weeks aging at room temperature, thirty-one percent (31%) of the initial concentration of ail-trans retinoi remained in Sample C.

¹⁵

From the foregoing aging results, it is concluded that the chemicai stability of all-trans retinol in an ou-in-water emulsion comprising all-trans retinoi, an oii-soiubie antioxidant (BHT) , a water-soluble antioxidant (ascorbicacid) and a cheiating agent (ethyieneoiaminetetraacetic acid) is chemically 20 unacceptable.

COMPARISON EXAMPLE 2

A phosonoiioid liposomal formulation of retinol (Vitamin A alcohol) was 25 prepared having the % wzw composition set forth in Tabie 2 at C1LAG AG,

After four weeks aging at 50*C, only 64.87% of the original amount of retinoi was founo in the formulation which does not meet the stability criteria.

ΆΡΙΡΙ 9 7/01 101

AP.00789

- 22 Table 2;

Ingredients	% \Nl\N
Water puritiea	81.44
Lecithin purifiea soya	7.50
Cholesterol	1 .00 |
Ethanoi	8.00 |
BHT	0.01 |
Metnyiparaoen	0.14
Propylparaben ·	0.01
Edetate Disoaium Dihydrate	0.10
Citric Acid Mononyarate	0.23
Sodium Hydroxide	| 0.44
Carbomer 934P	0.80
Retinol (45%)	0.33

o

Px.

CO (j!

COMPARISON EXAMPLE 3

A phoscnolipid liposomal formulation of retinol (Vitamin A alcohol) was prepared by BioZone according to U.S Patents Nos. 4,485.054 ana 4,751,23B. After four weeks aging at 50*C. only 64.61 % of the original amount of

AP.00789

- 23 retinoi was founa in me formulation which does not meet the stability criteria.

COMPARISON EXAMPLE 4

A non-phospnoiiDid liposomal formulation of retinol (Vitamin A alcohol) was prepared by Micro Vesicular Systems, inc. of New Jersey according to U.S. Patent No. 4,911,928. After 1 2 weeks aging at 5O*C, 40’C and room temperature only 58.1% , 79.4% and 89.3% respectively of the ^c oriainai amouni of rexinoi was found in The formulaxion which does nox _ meet the staoiiity criteria. C >

- The results c:eariy demonstrated that retinoi was more stable in both σ phospholipid and non-phosoholipid liposome type formulation than in the q oii-in-water emulsion. Although retinoi was partially stabilized by Q formulation type change from o/w to non-phosphoiipid liposome, the shelflife at ambient temperature was only 12 weeks, that is still chemically unacceptable.

EXAMPLE 5 and 6:

Retinol was encaosulateo in me non-phosoholipid liposome formulation with the following comoosition in accordance with the procedure set forth beiow. The pH of the final formulation was about 5.5.

AP.00789

- 24 Example 5 Example 6

	Oil Phase:	%W/W	%W/W
	Capryiic Caoric Triglyceride	10.00%	10.00%
5	Cholesterol	5.55%	6.80%
	Glyceryl Distearate	4.33%	5.30%
	Stearyl Aiconoi	3.90%	4.75%
	Stearetn-10	3.28%	4.00%
	Glyceryl Monostearate	2.08%	2.55%
TO	Polysoroate SO	1.00%	1.05%
	Tocooneroi Acetate	0.1 5%	0.34%
15	Butyiateo Hydroxy Toluene Water Phase:	0.05%	0.05%
	Deionized Water	68.14%	63.20%
	Citric Acid	0.13%	0.12%
	Sodium Hyaroxioe	0.03%	0.07%
	Metdyi Paraoen	0.20%	0.20%
20	Propyl Paraoen Active Inareoient:	0.03%	0.03%
	Retinoi (45% W/W)	1.12%	0.34%

Under a yellow light ano inside an argon blanker, wnicn served to aiminisf the amount of oxygen in tne formulation, the oil phase components wen mixeo togetner ano heated to a temperature of aboui 35°O. The ware

AP.00759

- 25 phase components were tnen mixed togetner and heatea to a Temperature of about 85°C ana Then cooiea to 60°C before phasing, the water phase was Then purgeo. with argon to remove oxygen. A Novosome* liposome maker, commercially available from Micro Vesicular Systems of New Jersey 5 and describea in U.S Patent Numoer 4,825,452) was 'eauiiibrated to a temperature of aoout 6O°C by pumping the water phase through the equipment. 1.13% of retinol (45% active was added to the oii phase. Both the water phase and the oii phase were pumped through the Novosome’ maker and the product was collected in a stainless steel 10 jacketed kettle imanufacturea by frymai wnich had been blanketed with argon. The Kettle was eauippea with a scraoer-stirrer, toothed colloid mill, dissolver ana vacuum deaeration system. The product was vacuumed until the pressure tn the kettle dropped to 0.8 mBar. The products were dispensed into proper packages under the argon blanket. Proper packages 15 may be selected from aiuminumrtubes, cans, pumps and/or sprays.

The stability results shown tn Table 3 ana 4 clearly illustrate that retinoi is more stable in example 5 and 6 than m example 4 and also meet the stability criteria 80% remaining at 50°C after 13 weeks of storage. There is no significant difference on tne staoiiity of retinoi as its concentration is changed from 0.153% to 0.504%.

KB V 0 / L ϋ /d/dV

AP . 0 0 7 8 9

- 25 Table 3. Retinol Stabilities in Example 5 at Various Temperatures.

5		% Retinol	% initial	pH j
	Initial j	0.5059	WO	5.53
	3 weeks	0.4498	88.91	5.32
	5OC
	8 weeks			I
TO	40 *C	0.4704	92.28	5.36
	50*C	0.4635	91.64	5.32
	1 3 weeks
	30'C	0.4884	97.0	5.37
	40 * C	0.4555	90.69	5.33
15	50*C	0.4355	86.5	5.22
	25 weeks
	30 V	0.4754	93.97	5.43
	40 C	0.4454	88.04	5.28

AP/P/ 9 7/01101

AP.00789

- 27 .

Table 4. Retinol Stabilities in Example 6 at Various Temperatures.

		% Retinoi	% Initiai	PH
	Initial	0.153	100	5.64
	4 weeks
	40* C	0.143	93.46	5.65
	5O*C	0.142	92.81	5.61
	8 weeks			|
	40 *C	0.1375	89.87	5.60
	5O'C	0.1355	88.56	5.56
	13 weeks
	4O*C	0.1335 .	87.25	5.55
	5O*C	0.1275	83.33	5.55
	20 weeks
	30*C	0.1375	89.87	5.69
	40* C	0.1 2Ξ5	84.64	5.62
	50*C _	0.1220	79.74	5.56

AP/P/ 9 7/01 101

AP.ο υ 7 8 δ

- 2S EXAMPLE 7:

To further improve tne formulations of this invention, a formulation with a water soluble antioxidant ascorbic acid ano a cnelating agent disodium EDTA was prepared in dark room without an Argon blanket set forth below..

The data summarized in Table 5 suggest that the stability of retinol in Example 7 was corriDaraale to Example 5 wnich was prepared without ^c ascoroic acic ano oisooium EDTA but under yellow light and Argon blanket.

The results also suggest tnat tne addition of ascorbic acid/disooium EDTA C might ennance tne cnemicai stability of retinoi in Novasome liposomes without the need for using an argon blanket. Thus, water-soluble σ antioxidants may also be utilized in the compositions of this invention such -n as ascorbic acid, sodium sulfite,· sodium metabisulfite, sodium bisulfite, £> sodium thiosulfite, sodium formaldehyde sulfoxylate, isoascorbic acid, thiogiyceroi, thiosoroitoi, thiourea, thiogiycoiic acid, cysteine hydrochloride. 1~4-diazobicycio-{2,2,2ioctane ana mixtures thereof.

AP.uu789 % W/W

	Glycerai Distearate	2.80%
	Choiesteroi	1.00%
	POE-IO Stearyl Alcohol	1.40%
5	Stearyl Alcohol ana Cetearetn-20	1.50%
	Cetearyi Alconol and Ceteareth-20	1.00%
	Cetyl Acetate ana Acetyiatea Lanoiin Alconoi	1.00%
	Dow Corning 344- Fluid Silicone Oil	5.00%
	Tocopheroi	0.15%
10	Butylated Hyaroxy Toluene	0.05%
	Glycerine	10.00%
	Methyl ParaDen	0.20%
	Propyi ParaDen	0.03%
	Sodium Chloride	0.10%
15	Polysorbate 80	0.75%
	Ascorbic Acid	0.10%
	Disooium EDTA	0.10%
	Butylene Giycoi	10.00%
	Cl 2-1 5 Alkyl Benzoate	6.70%
20	Retinol (45% W/W)	1.12%
	10 mM Citric Acid Buffer	57.00%

AP/P/ 9 7/01 101

AP . 0 0 7 8 9

- 30 Table 5. Retinol Stabilixv in Example 7.

	% RETINOL	% INITIAL	pH
INITIAL	0.491	100	5.56
5OC
3 weeks	0.459	93.48	5.56
7 weeks	0.449	91 .45	5.47
1 2 weeks	0.407	82.S9	5.60

AP/P/ 9 7/01 101

AP . 0 0 7 8 9

EXAMPLE 8:

To improve the cosmetic elegance of the retinol formula, the non5 phospholipid liDOsomai formulation of retinol (Example 8A ) was physically mixed with various proportions of 80% w/w cyclomethicone loaded nonphospnolioid liposome (Examole 8E). The stability results are summarized in

Tables 6 througn 8.

AP/P/ 9 7/01 101

AP . θ Ο 7 8 9

Example 8A

Water

Capryiic Capric Trigiycenae

Glycerin 96%

Butylene Glycol Cholesterol Glyceryl Distearate Stearyl Alconol

TO Stearetn-IO

TocoDneroi Acetate Glyceryl Monostearate Poiysoroate SO Retinoi (45% W/W)

Citric Acid

Sodium Hydroxide Methyl ParaDen Disooium EDTA Butylated Hyoroxy Toluene

Ascorbic Acid Propyi Paraoen % W/W

54.95%

6.00%

10.00%

10.00%

3.95%

3.15%

2.85%

2.50%

2.00%

1.55%

1.00%

0.75%

0.50%

0.25%

0.20%

0.10%

0.10%

0.10%

0.03%

AP/P/ 9 7/01 101

AP.00789

Λ »·>

- UU> Example 8B (30% w/w Cvclomethicong Loaded Non-phospholipid Liposome) % W/W

Water	40.10%
Cyciometnicone	30.00%
Glyceryl Distearate	7.95%
Glycerin 95%	7.00%
1,3-Butyiene Giycci	7.00%
Steareth-10	3.98%
Cholesterol	1.97%
Sodium Citrate	0.95%
Polysordate 80	0.52%
Citric Acid	0.16%
Methyl Paraoen	0.14%
Tocopherol Acetate	0.11%
Ascorbic Acid	0.07%
Disooium EDTA	0.07%
Propyl Paraoen	0.02%

AP/P/ 9 7/01 101

AP.00789

Table 6. Example 8C [50% Example 8A St 50% Example 8B)

		% Retinal	% Initial	pH
5	Initial	0.1735	100	5.56
	4 weeks			5.54
	40*0	0.1705	98.27	5.54
	5O*C	0.1690	97.41
	1 8 weeKs
10	40*0	0.1 620	97.41	5.53
	50*0	0.1 670	96.25	5.56
	1 3 weeks
	30*0	0.1660	. 95.68	5.52
	40*C	0.1 650	95.10	5.58
15	5O*C	0.1580	j 91.07	5.57
	20 weeks
	30*0	0.1715	98.84	5.61
	40*0	0.1655	95.32	5.60
	5O*C	0.1550	83.34	5.60

AP/P/ 9 7/01 101

AP.00789

- 35 Table 7. Example 8D (60% Example 8A and 40% Example 8B)

r	% Retmol	% Initial	—————————..... pH
	Initial	0.1900 j	100	5.62
	4 weeks
	4O*C	0.1869	98.37	5.57
	5O*C	0.1831	96.37	5.57
	8 weeKs
	3O'C	0.1 896	99.77	5.57
	40*C	0.1858	97.78	5.64
	5O*C	0.1816	95.59	5.62
	13 weeks		1
	3O'C	0.1867	98.25	5.65
	40'C	0.1809	95.21	5.64
	5O’C	0.1750	92.11	5.64

PIP/ 9 7/01 101 £P 0 0 7 8 9

- 36 Table 8. Examoie 8E !70% Examoie 8A ana 30% Example 8B1

	| % Retinol	% Initial	pH J
	Initial |	0.2235	100 |	5.64
	4 weens
	4O’2	0.2201	9S.5O	5.64
	50’C | I	0.2161	96.70	5.62
	8 weens
	30*2	0.2213	9S.0A	5.62
	4O'2	0.2181	97.58	5.67
	50*2	0.2138	95.67	5.66	j
	1 3 weens	1	1	||
	30*2	0.2205	98.65	5.66
	40*2	0.2146	96.02	5.66	j
	50*2	| 0.2075	22.84	5.67	I

AP/P/ 9 7/01 101

The aata'suggest that mere are no significant cnanges in stability of a nan20 phosonotipid lioosomai retinol formulation wnen it is mixea with 30-50% af 30% cyciometnicone loaaeo non-pnospnoiicia tioosome formulation to render cosmetic elegance to the primary formula. This was of great significance because the eiegance cnaracteristic is of orotouno imconance for customs; comeiiance.

AP.00789

- 37 Example 9:

The Effect ef pH on Stability cf Retinol in a Non-Phospholipid Liposon

Formulation.

To aefine the pH range most useful for retinot-containing compositions of this invention, the pH of Example 8D was adjusted to pH's ranging from 3.6 to 7.4 with dilute hydrochloric acid or dilute sodium hydroxide. The samples were stored at different temperatures (4'C, 3O*C. 40'C and 50*0. Samotes were taken oerioaicaily for both pnysicai and chemical evaluation.

o

The results in Figure 1 cleariy snowed that ootimai pH range for retinol r— cream at 50*0 was aoove 5 .

EXAMPLE 5:

In-vitro Bioavaiiabiiity of Liposome Formulations cr>

Skin bioavaiiabiiity, wnicn is defineo by tne availability of drug released from the formulation as weil as the extent of skin penetration after application, usually serves as a good indicator for drug efficacy. The in-vitro bioavaiiabiiity of retinol was determined by standard in-vitro release and skin penetration tests using FRANZ diffusion cells. For the release study, a weighed amount of cream was applied on a synthetic membrane mounted on each of the FRANZ diffusion cells. The synthetic membrane functioned as a cream supporter and did not cause significant resistance to the drug release. Samoies were taken from the receptor chamoer at predetermined intervals. The amount of retinol released from the formulation to the receptor solution was determined by High Pressure Liauid Chromatography

AP.00789

- 38 (HPLC). The results in Figure 2 cleariv showed that the release of retinol from non-pnosDnolioid iiDosome ExamDie 8C is mucn faster than that from RoC s.a (water-in-oii, 0.15% retinoi) formulation, a stable retinoi water-in-oil cream proouced'accoraina to Wang, et.al. pending patent on the market.

At the end of 7 hours, approximately 1 0% and 5% of retinol were released from non-pnospnoiioid liposome and RoC s.a respectively.

The in-vitro skin penetration study was conducted using a similar protocol as the release study except that human cadaver skin was used instead of a

0 synthetic membrane. At the end of 48 hrs of experiment, the skin surface was C thoroughly cleaned and the amount of retinol penetrated was analyzed by , HPLC. It was found that non-phospholipid liposome formulations can be engineered to provide a wide range of bioavailabilitv. For example. Example _t 8C (which is a 50:50 mixture of 0.34% retinoi loaded non-phospholipid ‘ liposome and 30% cyclomethicone loaded non-phospholipid) yielded much | higher retinol skin penetration compared to the RoC s.a product. On the other hand. Example 6 (0.15% reunol loaded non-pnospnolipid) provided similar skin penetration to RoC s.a product (Figure 3).

EXAMPLE 10:

Dermal Irritation Test:

Retinol-containing non-phospholipid liposome formulations were evaluated for 25 dermal irritation and were also compared with' a water-in-oii retinoi formulation.

Ά 0 0 7 8 9

Scope and Procedure

The modified Draize Rabbit Primary Dermal Irritation Test is a procedure for predicting the ability of test articles to elicit inflammatory responses upon prolonged occluded contact with intact and intentionailv-abraded New Zealand white rabbit skin. Following a timed exposure period, the test articles are removed and the application sites were evaluated. From this data, a Primary Dermai Irritation (PDI) Index is calculated for each test article and a classification is assigned. ° vThe test article was applied with 0.25-0.30g to 25mm Hilltop Chambers ^ο

X.

containing non-woven Webrii pads., The chambers were then applied to the appropriate test sites and held in place with strips of Dermicel tape. The trunk ^σ' of the animals were wrapped to occlude the sites and to keep the test articles £* f£ in place. After the 4 hours of exposure, the test articles were removed and readings were taken after one hour in order to allow the skin to equilibrate. After the equilibration period, the sites were examined and then again reexamined after 72 hours of application for signs of dermai irritation and were graded using a scale as follows:

PDIIndex

0.0

0.1 - 2.0

2.1 - 5.0

5.1 - 8.0

Classification

Non-irritant Mild Irritant Moderate imtcnt Severe imtant

AP.00789

- 40 Table 9:

		| PDI	Classification
5		Formulation	0.9	Mild irritant
		6(0.15% Retinol)
	Study I	Placebo (negative	0.7	Mild Irritant
		control)
		w/o-1 (0.15% j	1.7	Mild Irritant
		Retinol	0.5	Mild Irritant
		Placebo (negative
		control)
		Formulation SC	3.0	Moderate Irritant
		(0.15% Retinoi)
10	Study Π	Placebo (negative	2.2	Moderate Irritant
		control)
		w/o-II (0.15%'	2.4	1 Moderate Irritant
		Retinol)
		Placebo (negative	1.2	Mild Irritant
		control)

110 1

D'CD

a.

A i<U«·

AP.00789

P/ 9 7 / 0 1 10 1

- 41 In general, the irritancy of topical formulation arises from both the active and the surfactants. The results in Table 9 show that 0.15% retinoi w/o formulations, which contain approximately 2% surfactants, exhibit mild or marginally moderate irritancy. Surprisingly, 0.15% retinol non-phospholipid 5 liposome formulations, which contain more than 8% surfactants, show similar irritancy as that of w/o formulation tested. The resuits suggest that nonphospholipid liposome formulations may have a potential to reduce the irritancy from the ingredients of the formulations.

EXAMPLE 11:

Evaluation of Cosmetic Performance:

Three non-pnospnolioid liposomal formulations and a water-in-oii emulsion (a 'Tf stable retinol product marketed by RoC s.a,) containing 0.15% retinoi were *^v<* evaluated for quantitative descriptive analysis (QDA). The commercial product Night of Olav⁵ from Procter &. Gamble was used as a control. The objective of this evaluation was to determine the overall cosmetic attributes of the retinol creams. The evaluation was performed by a trained panel of scientists. The parameters which were evaluated were appearance in cup, feel between fingers, feel during application and skin feci after application.

The results for the various elements after application are shown in Figure 4 along with the same for Night of Olay for easy comparison. The results suggest that retinoi liposome formulations were preferred over retinol in water-in-oil. The results also suggest that greasiness which is a big drawback for water-in-oii

AP.00789

- 42 emulsion can be controlled with slight modification of the liposomal formulation without compromising the stability of retinol. The results of comparisons of the formulations of Examples 6. S and two commercial compositions are set forth in Fig. 4.

According to above observations. the products of this invention unexpectedly provide chemical stability enhancement, bioavailabilitv programmability of retinoids to the skin, as well as improvement of the cosmetic elegance of the vehicle, which can ail be achieved in a single non-phospholipid liposome formulation.

Claims (15)

1. WHAT IS CLAIMED IS:

   1'. A composition for stein core comprising a non-phospholipid liposome and a retinoid selected from the group consisting of retinoi. retinal, retinvl acetate, retinyi palmitate and mixtures thereof, said composition further comprising a stabilizing system selected from the group consisting of:

   a) an cil-sciuble antioxidant: and

   b) a chelating agent and at least one oii-soiuble antioxidant:

   wherein said composition has a pH from at least about 5 to about 10, said composition retaining at least S0% of satd retinoids after 13 weeks’ storage at 50c C.
2. 2. A composition according to claim 1 wherein said retinoid is Vitamin A alcohol.

   A composition according to ciaim 1 wherein said retinoid is retinyl acetate or retinyl· palmitate.
3. 4. A composition according to ciaim 1 wherein said retinoid is Vitamin A aldehyde.
4. 5. A composition according to claim 1 wherein said oii-soiuble antioxidant is selected from the arouo consisting of butvlated hvdroxvxoiuenc.

   AP 00789

   - 44 ascorbvi palmitate. butylated hvdroxyanisoie. α-tocopherol. phenyi-anaphthyiamine and mixtures thereof.
5. 6. A composition according to claim 1 wherein said chelating agent is

   5 selected from the group consisting of ethvlenediamine tetraacetic acid and derivatives and salts thereof, dihydroxyethvl giycine. citric acid, tartaric acid, and mixtures thereof.
6. 7. A composition according to claim 6 wherein said chelating agent is * XT

   10 selected form the group consisting of ethvlenediamine tetraacetic acid c and derivatives and saits thereof.·

   T

   C
7. 8. A composition according to claim 1 wherein the pH of said composition is from about 5 to about 7. <

   15 f
8. 9. A skin care composition comprising a non-phospholipid liposome and a retinoid selected from the group consisting of retinol, retinal, retinyl acetate, retinvi palmitate and mixtures thereof, said composition further comprising a stabilizing system comprising an oil-soluble antioxidant.

   20 wherein said composition has a pH from at least about 5 to about 10, said composition retaining at least 80% of said retinoids after 13 weeks’ storage at 500C.
9. 10. A composition according to ciaim 9 wherein said uh· soluble antioxidant

   25 is selected from the group consisting of butylated hydroxvtoluene.

   AP . 0 0 7 8 9

   - 45 ascorbyl paimitate. butyiated hydroxvanisole. o-tocopheroi, phenyl-anaDhthviamine and mixtures thereof.

   ll. A skin care composition comprising a non-phospholipid liposome and a retinoid selected from the group consisting of retinol, retinal, retinyi acetate, retinyi palmitate and mixtures thereof, said composition further comprising a stabilizing system comprising at least one oil-soiuble antioxidant and a chelating agent, wherein said composition has a pH from at least about 5 to about 10, said composition retaining at least 80% of said retinoids after 13 weeks’ storage at 50OC.
10. 12. A composition according to claim 11 wherein said oil-soluble antioxidant is selected from the group consisting ‘ of butyiated hydroxytoiuene, ascorbyl palmitate, butyiated hydroxvanisole, a-tocopherol, phenyl-anapnthvlamine and mixtures thereof.

    o r* cx
11. 13. A composidon according to claim 1 1 wherein said chelating agent is selected form the group consisting of ethyienediaminc tetraacctic acid and derivatives and salts thereof, dinydroxyethvl glycine, citric arid, tartaric acid, and mixtures thereof.
12. 14. A composition according to claim 9 wherein said retinoid is Vitamin A aicohol.

    25'
13. 15. A composition according to claim 11 wherein said retinoid is Vitamin

    A aicohol.

    AP. u υ 7 8 9

    - 46
14. 16. A composition according to claim 9 wherein the pH is from about 5 to about 7.
15. 17. A composition according to claim 11 wherein the pH is from about 5 to

    5 about 7.