Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2000-12-06
2004-08-10
Mruk, Brian P. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S130000, C510S157000, C510S158000, C510S159000, C510S404000, C510S434000, C510S477000, C424S070160, C424S070170
Reexamination Certificate
active
06774100
ABSTRACT:
BACKGROUND
1. Technical Field
This disclosure relates generally to substantially anhydrous compositions, such as anhydrous creams, lotions and gels useful in the cosmetic or pharmaceutical industries. More particularly, this disclosure relates to substantially anhydrous compositions containing a polar solvent, a thickening agent and, preferably a beneficial agent, especially a beneficial agent that is unstable in aqueous media.
2. Background of Related Art
Creams, lotions and gels are frequently used as topical treatments in the pharmaceutical and cosmetic industries to deliver beneficial agents to the skin of a user. Whether used to deliver a drug or a skin softener, the consistency and feel of the composition is important to the commercial success of the product. Stability of the beneficial agent in the composition is another important consideration in formulating such products.
Thickeners which have been previously used in formulating creams, lotions and gels include several commercially available acrylic acid polymers and polyacrylamides. However, the manufacturers of these thickeners consistently recommend that to provide a desired viscosity the thickener should be dispersed in water and then neutralized. Acrylic acid polymers and polyacrylamides have thus been found quite useful where an aqueous formulation is acceptable. However, some very important beneficial agents are unstable over time in aqueous systems. Included among the beneficial agents which are unstable over time in aqueous systems are several antibiotics and vitamins. Such beneficial agents are preferably delivered via anhydrous formulations. Acrylic acid polymers and polyacrylamides, which are promoted with literature that recommends dispersion in water to provide viscosity, are not known to be useful for imparting viscosity to anhydrous formulations.
SUMMARY
It has now been found that substantially anhydrous compositions having a viscosity greater than 1000 centipoise can be prepared by combining a polar solvent with a thickening agent selected from the group consisting of acrylic acid polymers and polyacrylamides. These compositions are particularly suited for topical use to deliver beneficial agents to the skin of a user. Preferred polar solvents are polyhydric alcohols. The thickening agent is added to the polar solvent in an amount sufficient to provide a desired thickness. Being anhydrous, the compositions are particularly well suited to effectuate the delivery of beneficial agents that are unstable over time in aqueous systems.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The compositions described herein are substantially anhydrous and contain a polar solvent, a thickening agent and, in particularly useful embodiments, a beneficial agent.
The compositions have a viscosity greater than about 1000 centipoise (cps) when measured using a Brookfield viscometer (model LVT) at room temperature using spindle number 3 or 4 at 30 to 0.3 rpm. It should be understood that all viscosities referred to herein are measured in this manner. Preferably, the composition has a viscosity greater than 5,000 cps. In particularly useful embodiments, the composition has a viscosity in the range of from about 1000 to about two million centipoise. Most preferably, the compositions have a viscosity in the range of about 10,000 cps to about 1,000,000 cps.
The compositions are also substantially anhydrous. That is, other than water of hydration contained in the various components used to formulate the product, no free water is added to the composition. Typically, the water content of the composition will be less than 5% by weight. Preferably the water content of the composition is less than 3% and most preferably less than about 1% by weight of the composition.
Polar solvents useful in the present compositions include polyols. A polyol is a compound with at least two hydroxyl groups per molecule, i.e., a compound having multiple hydroxyl groups as part of its molecular structure. Among the useful polyols are polyhydric alcohols. Propylene glycol, dipropylene glycol, polyethylene glycol and glycerine are particularly preferred polar solvents for use in the present compositions.
The thickening agent used in the present compositions is selected from the group consisting of acrylic acid polymers and polyacrylamides. The thickening agent are used in an amount sufficient to obtain a composition of viscosity in the desired range.
Useful acrylic acid polymers include copolymers of (meth)acrylic acid and of monomers containing at least one fatty chain; these monomers are chosen from hydrophobic monomers with a fatty chain, amphiphilic monomers containing a hydrophobic part with a fatty chain and a hydrophilic part, or alternatively their mixtures. Suitable materials include, for example, copolymers of C
10-30
alkyl acrylates with one or more monomers of acrylic acid, methacrylic acid, or one of their short chain (i.e., C
1-4
alcohol) esters, wherein the crosslinking agent is an allyl ether of sucrose or pentaerythritol. These copolymers are commonly referred to as acrylates/C
10-30
alkyl acrylate crosspolymers and are commercially available under the tradename CARBOPOL® from B.F. Goodrich, Cleveland, Ohio U.S.A. Other polymers useful in the preparation of the present compositions are polymers of polyacrylic acid crosslinked with from about 0.75% to about 2.0% of polyalkyl sucrose or polyalkyl pentaerythritol often with molecular weights of 4 to 5 million or more that are commercially available, for example, under the trade designation CARBOPOL® 934, 940 and 941 from B.F. Goodrich, Cleveland, Ohio U.S.A. Anionic amphiphilic polymers which comprise 95% to 60% by weight of acrylic recurring structural units, 4% to 40% by weight of acrylate recurring structural units and 0. 1% to 6% by weight of crosslinking monomer, or (ii) which comprise 98% to 96% by weight of acrylic recurring structural units, 1% to 4% by weight of acrylate recurring structural units and 0. 1% to 0.6% by weight of crosslinking monomer are also useful as the thickening agent in the present compositions. Such polymers include, for example, those hydrophobically-modified cross-linked polymers of acrylic acid having amphipathic properties marketed by B.F. Goodrich under the trademarks CARBOPOL 1342 and CARBOPOL 1382. Also useful is ULTREZ® 10 (available from B.F. Goodrich), an oil in water emulsion of a modified acrylic copolymer comprising of a major portion of a monoolefinically unsaturated carboxylic acid monomer or its anhydride having a length of from about 3 to 6 carbon atoms and a minor portion of a C
8-30
chain acrylate or methacrylate ester monomer wherein the carboxylic acid or its anhydride is from about 80 to about 99% by weight and the C
8-30
chain acrylate or methacrylate ester monomer is from about 1% to about 20% by weight. The polymer is described in U.S. Pat. No. 5,004,598, hereby incorporated by reference in its entirety.
When used, these acrylic acid polymers are present at a level from about 0.05% to about 20%, preferably from about 0.5% to 10% and most preferably from about 1% to about 10%.
The compositions can alternatively contain polyacrylamide polymers as the thickening agent, especially nonionic polyacrylamide polymers. The non-ionic polymers useful in the present compositions are polyacrylamides and substituted polyacrylamides, branched or unbranched. These polymers are non-ionic polymers which can be formed from a variety of monomers including acrylamide and methacrylamide which are unsubstituted or substituted with one or two alkyl groups (preferably C
1-5
). Preferred acrylate amides and methacrylate amides in which the amide nitrogen is unsubstituted, or substituted with one or two C
1-5
alkyl groups (preferably: methyl, ethyl or propyl), for example, acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N,N-dimethylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide and N,N-dimethylacrylamide. These monomers are generally disclosed in U.S. Pat. No. 4,963,348 which is incorporated by reference herein in i
Carter DeLuca Farrell & Schmidt LLP
Imaginative Research Associates Inc.
Mruk Brian P.
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