Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-07-25
2002-04-02
Woodward, Ana (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S500000, C524S503000, C524S504000, C524S514000, C524S538000, C524S539000, C524S542000
Reexamination Certificate
active
06365664
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of stable, irreversible, hydrophilic gels and more particularly to blends of poly(amide, amine or alcohol) and hydrophilic poly(aldehyde) which can be used in dressings for a variety of applications including cosmetic applications.
It has been known that polyvinyl-pyrrolidone (PVP) complexes with polyurethanes to yield hydrophilic blends which can be used as wound dressings or in cosmetic preparations. For example, U.S. Pat. No. 5,156,601 discloses a dressing which includes a tacky gel of polyurethane and a poly(N-vinyl lactam) such as PVP with a degree of ring opened pyrrolidone groups. U.S. Pat. No. 5,420,197 describes hydrophilic gels formed by poly(N-vinyl lactams) such as PVP with a degree of ring-opened pyrrolidone groups, and chitosans. Other references of general background interest include U.S. Pat. Nos. 5,135,755 and 5,206,322.
Although some of the hydrophilic gels described in the art can be used for wound dressings and other dermatologically compatible applications, many hydrophilic gels known in the art are reversible and have a tendency to cold flow. Accordingly, there is still a need in the art of dressings, implants and dermatological compositions for gels which are irreversible and do not exhibit cold flow.
It is therefore an object of the invention to provide dressing compositions and dermatologically-compatible compositions which include gels having hydrophilic and absorbent properties and which do not exhibit cold flow.
It is a further object to produce gels without a need for expensive equipment and/or processing.
It is another object to provide gels of poly(aldehyde) and poly(alcohol, amine, amide) which can be used in a variety of products such as cavity dressings, drug delivery patches, face masks, implants and wound dressings.
SUMMARY OF THE INVENTION
The present invention, which addresses the needs of the prior art, provides irreversible, hydrophilic gels which can be incorporated into dressing compositions, dermatologically compatible compositions, wound packings, wound dressings, burn dressings, drug delivery dressings, dry films, cosmetic masks and cosmetic wTap dressings. In one aspect of the invention, the gels include a blend of a hydrophilic poly(aldehyde) and a polymer selected from the group consisting of a poly(amide), a poly(amine) and a poly(alcohol) and mixtures thereof.
The hydrophilic poly(aldehydes) useful in preparing the gels of this aspect of the invention include, but are not limited to, a homopolymer, a (co)polymer or a terpolymer of acrolien, vinyl formal, glutaric dialdehyde and mixtures thereof. Poly(amides) useful in forming the gels include, but are not limited to, a homopolymer, (co)polymer or terpolymer derived from acrylamide, N-vinyl lactams, N-vinyl formal and mixtures thereof. Poly(amines) useful in preparing the gels of the present invention include, but not limited to, a homopolymer, (co)polymer or terpolymer derived from ethylene diamine, allylamine, vinyl pyridine, N-vinyl formal, chitosan, vinyl amine and mixtures thereof. Poly(alcohols) useful in the present invention include a homopolymer, (co)polymer or terpolymer derived from hydrolyzed poly(vinyl acetate), allyl alcohol, ethylene glycol, ethylene oxide and mixtures thereof.
In another aspect of the invention, the gels include two components. The first component includes a water-soluble (co)polymer, which is preferably from about 1 to about 50 weight % in a solution. The water-soluble (co)polymer of the first component is prepared by grafting (meth)acrolin onto a (co)polymer. The second component includes a water soluble (co)polymer, which is preferably from about 1 to about 20 weight % in a solution. The water soluble (co)polymer of the second component is functionalized with an amino group, alcohol, acid, or mixtures thereof.
In another embodiment, the (meth)acrolien can be grafted onto poly(ethylene oxide), poly(propylene oxide), or homopolymers or (co)polymers of ethylene glycol or N-vinyl pyrrolidone. The water soluble (co)polymer containing amide, alcohol or acid functionality includes poly(ethylene imine), poly(vinylalcohol), chitosan, cellulose, poly((meth)acrylic acid)), and (co)polymers thereof. The weight ratio of the first component to the second component can be from about 12:1 to about 1:1.
The gel is prepared in an aqueous solution at a total polymer concentration of from about 5 weight % to about 50 weight %. The aqueous solution comprises water or a mixture of water and alcohol.
In another embodiment, the hydrophilic gel includes at least one additional ingredient selected from the group consisting of a surfactant, a fragrance, and a biologically active material. The additional ingredient can be releasable from the hydrophilic gel. The additional ingredient can include nitroglycerin, scopolamine, pilocarpine, ergotamine tartrate, phenylpropanolamine, theophylline, tetracycline, nemoycine, oxytretracycline, triclosan, sodium cefazolin, silver sulfadiazine, salicylates, nicotinates, capsaicin, benzocane, &agr;-hydroxy acids, vitamins, biostats or mixtures thereof.
In another embodiment, the (meth)acrolin is (co)polymerized with N-vinylpyrrolidone or N-caprolactam.
The functionalized water soluble (co)polymer can be poly(ethylene imine), poly(vinyl alcohol), chitosan, cellulose, poly((meth)acrylic acid)) or (co)polymers thereof.
The gel is prepared in an aqueous solution at a total polymer concentration of from about 5 weight percent to about 50 weight percent. The aqueous solution comprises water or a mixture of water and alcohol.
In another embodiment, the hydrophilic gel further includes at least one substrate. The substrate is selected from the group consisting of polymer film, polyutherane film, polyester film, poly(amino acid), collagen film, woven fabric, and non-woven fabric. The substrate can be stretchable. Examples of substrates include, but are not limited to, a release liner and a cell culture.
Another aspect of the invention is related to a method for preparing a stable, irreverisable hydrophilic gel. The method includes mixing an aqueous solution of a poly(aldehyde) or (co)polymer with an aqueous solution of a poly(amine), poly(alcohol) or a poly(amide) in a weight ratio from about 12:1 to about 1:1. The resultant solution is then cured until a gel is formed. The curing is preferably performed for a period of time of from about 10 seconds to about 2 hours.
In another embodiment, the method for preparing a stable, irreverisable hydrophilic gel includes adding a biologically active material to the mixture of aqueous solutions. The biologically active material can be an anti-microbial agent.
The gel can be formed into a dressing by casting two separate slabs of said gel onto two substrates, applying a solution of a biologically active material onto a surface of one of the slabs, and compressing the slabs together with the biologically active material located between the slabs.
The gel preferably includes at least one additional ingredient which may be releasable from the gel. Preferably, the releasable ingredient is a surfactant, a fragrance, a biologically active material, or a bioeffecting or body-treating material.
The dressing compositions of the present invention have the advantage of self-adhesion to the skin but with facile peelability. As a result of the present invention, gels are provided which are stable even in hot water, are capable of absorbing many times their weight in water, and are capable or delivering medicaments externally to the body exactly where desired. Most importantly, the products based on the gels of the present invention have the unexpected property of resisting cold flow.
Other improvements which the present invention provides over the prior art will be identified as a result of the following description which sets forth the preferred embodiments of the present invention. The description is not in any way intended to limit the scope of the present invention, but rather only to provide a working example of the present preferred embodim
Hoffmann & Baron , LLP
Hydromer, Inc.
Woodward Ana
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