Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2000-02-25
2001-08-28
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
Reexamination Certificate
active
06280753
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cosmetic and/or therapeutic products. In particular, the invention relates to wax-based products containing water in the formulation.
BACKGROUND OF THE INVENTION
In recent years, lipstick has gone beyond the point of serving the sole function of coloring the lips. Consumers are no longer satisfied with a product which serves a simple cosmetic purpose; rather, the demand is now for a product which, in addition to providing an attractive appearance, goes on smoothly, lasts all day, and also moisturizes and improves the condition of the lips. The goals of moisturizing and conditioning have proven particularly difficult when using standard lipstick formulations.
Traditional lipsticks have primarily been anhydrous, i.e., they have been composed principally of hydrophobic waxes and oils. Such products have relied on the formation of a thick occlusive film on the lips to prevent moisture loss. While to a large extent very effective in preventing water loss, such anhydrous systems are unable to achieve the more desirable end of actively reconstituting the lips' lipid barrier or attracting and binding water to the lip surface. This is largely because the low polarity and high viscosity which characterize the typical waxy components, act as a barrier to active product diffusion. Moreover, these viscous materials frequently result in a product that leaves an undesirable greasy or waxy feeling on the lips.
Notwithstanding the problems which arise with their use, the hydrophobic waxes and oils are an essential part of virtually any lipstick, in that they confer the solid physical structure required for ease of application. It has been recognized that the availability of a water-containing lip product would obviate many of the problems associated with the anhydrous systems. For example, many of the therapeutic or conditioning actives which would be useful in barrier repair or moisture attraction are water soluble. ideally, the use of a water-in-oil emulsion system would provide the combination of features which would both confer both occlusive film-forming properties and structural integrity to the stick while still permitting delivery of the water soluble and/or water attracting actives to the lips. Nonetheless, the cosmetics industry has, to date, produced few such systems. In part, the difficulty arises in the inherent incompatibility of water with the low polarity waxes and oils; however, there are also serious problems with loss of water from the stick during storage, and the lack of stability of the water soluble actives in such a system. Generally speaking, the available systems rely entirely on the use of emulsifiers (see e.g., U.S. Pat. No. 5,342,134) to stabilize the contained actives. Since the trend in cosmetics is away from the use of emulsifiers, however, it would be preferable to design a water-in-oil emulsion system which does not rely solely on standard emulsifiers for stability of actives contained therein.
Therefore, there continues to be a need for a water-containing lip product which can moisturize and protect the lips, deliver stable water soluble actives without the use of large amounts of standard emulsifiers or surfactants, and which is not susceptible to rapid loss of water from the mass. The present invention provides such a product, and solves many of the problems encountered with other water-containing lip products.
SUMMARY OF THE INVENTION
The present invention relates to a wax-based composition comprising at least about 0.5-30% water in a water-in-oil emulsion, wherein water is encapsulated in a lamellar lipid vesicle capable of withstanding the temperatures encountered in a hot-pour process, i.e., wax or wax-like materials' melting point temperatures. By “wax-based” is meant a product which contains over 5% by weight, more preferably over 10%, of wax or a wax-like product in the formulation. The vesicle preferably has walls comprising at least one high melting point polyoxyethylene fatty acid ether, which confers the high temperature stability required for pouring lipstick or other wax-based products. The products so prepared lose water at a slower rate than other water-containing lip products, and are capable of maintaining the stability of water soluble actives contained within the vesicle. In a preferred embodiment, the wax base is designed to contain several products with a relatively moderate to high level of polarity, so as to enhance compatibility with the water-containing vesicle.
DETAILED DESCRIPTION OF THE INVENTION
The use of lamellar vesicles to encapsulate and deliver both cosmetic and pharmaceutical actives has now long been established. In brief, these vesicles comprise one or more lipid layers, each surrounding a small aqueous volume. Such vesicles and methods of making same have been described in, for example, U.S. Pat. Nos. 4,895,452, 4,855,090, 4,911,928, 4,917,951, 4,942,038, 5,000,960, 5,013,497, 5,023,086, 5,032,457, 5,104,736, 5,147,723, 5,160,669, 5,213,805, 5,219,538, 5,234,767, 5,256,422, 5,260,065, 5,405,615, 5,439,967, and 5,474,848. The contents of each of these is incorporated by reference in its entirety. This type of vesicle is widely recognized as facilitating delivery of a number of different types of actives to a desired target site. A particularly useful type of lamellar vesicle for the present purpose is one which is primarily non-phospholipid in nature. Such vesicles can be made from a wide variety of different components, as can be readily discerned from the cited references. A typical example of the components of an appropriate vesicle are, for example, a sterol, such as cholesterol; one or more surfactants (for example, fatty acids, fatty alcohols, and ethoxylated derivatives thereof, or sorbitan derivatives), and other oils or lipids. However, such vesicles have not previously been used in lipsticks, as the most commonly used components of the vesicle wall typically have a temperature stability maximum of about 50° C.; therefore, the vesicles cannot withstand the high temperature required in the preparation of lipsticks, or other hot-pour products.
It has now been determined that the use of an polyoxyethylene fatty ethers having a melting point greater than that of the waxes being used is adequate to stabilize the other more heat labile components of the vesicle. Preferably, the combined wall materials, including the ether, overall have a melting point at least 2° C. above that of the waxes or wax-type products being used in the hot-pour. Using a lipstick as an exemplary wax-based product, the melting point of the ether is preferably at least about 80° C., preferably at least about 90° C., and more preferably at least about 100° C. The ether is present in an amount of from about 0.01-8%, preferably from about 0.1-5%, and more preferably form about 0.5-4%. Preferred compounds of this type include long chain (i.e., at least C20) polyethylene glycol ethers of a mixture of fatty alcohols with an average of at least 3 moles of ethylene oxide. Particularly preferred are such alcohols having a chain length of at least C40, and an average of 3 moles of ethylene oxide, for example, C40-C60 pareth-3.
The remaining components of the vesicle can be any of those which are standard in the art, as noted above. In particular, vesicle components are described in detail in the U.S. Patent documents listed above, which are incorporated by reference herein. In a preferred embodiment, the lipid layer of the vesicle comprises, in addition to the high melting point ether, a least one other standard polyoxyethylene fatty acid ether, for example polyoxyethylene (n) cetyl, stearyl, oleyl, or linoleyl ethers, wherein the average n value can be from 2-10. Other standard surfactants can also be incorporated into the lipid portion. Preferably, the lipid portion also comprises a sorbitan derivative surfactant, for example, polyoxyethylene sorbitan fatty acid esters(TWEEN, ICI). The lipid layer will also comprise a steroid component. This is preferably a sterol, for example cholester
Chung Kenny
Keeler Tracy N.
Tan Manuel L.
E-L Management Corporation
Howard S.
Page Thurman K.
Pennie & Edmonds L
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