Hydrogel compositions
Hydrogel compositions are provided (a) that have a continuous hydrophobic phase and a discontinuous hydrophilic phase, (b) that have a discontinuous hydrophilic phase and a continuous hydrophilic phase, or (c) that are entirely composed of a continuous hydrophilic phase. The hydrophobic phase, if present, is composed of a hydrophobic polymer, particularly a hydrophobic pressure-sensitive adhesive (PSA), a plasticizing elastomer, a tackifying resin, and an optional antioxidant. The discontinuous hydrophilic phase, if present, is composed of a crosslinked hydrophilic polymer, particularly a crosslinked cellulosic polymer such as crosslinked sodium carboxymethylcellulose. For those hydrogel compositions containing a continuous hydrophilic phase, the components of the phase include a cellulose ester composition or an acrylate polymer or copolymer, and a blend of a hydrophilic polymer and a complementary oligomer capable of hydrogen bonding thereto. Films prepared from hydrogel compositions containing or entirely composed of the aforementioned continuous hydrophilic phase can be made translucent, and may be prepared using either melt extrusion or solution casting. A preferred use of the hydrogel compositions is in wound dressings, although numerous other uses are possible as well.
1. A delivery system for topical administration of a locally active agent to the skin, the system comprising:
a body-surface contacting layer comprised of an adhesive hydrogel composition positioned on a backing layer, the adhesive hydrogel composition comprising:
(i) a water-swellable, water-insoluble polymer in an amount ranging from about 2 weight percent to about 15 weight percent of the hydrogel composition, wherein said polymer is insoluble in water within a selected pH range and is an acrylate copolymer comprising monomers selected from the group consisting of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate, and wherein the acrylate copolymer has a ratio of free carboxyl groups to ester groups in a range of about 1:1 to 1:2;
(ii) a blend of a hydrophilic polymer and a complementary oligomer, where the hydrophilic polymer is a poly(N-vinyl lactam), the complementary oligomer is a low molecular weight polyalkylene glycol having a molecular weight of 300 to 600 daltons, and the hydrophilic polymer represents about 75 weight percent to about 25 weight percent of the hydrophilic polymer-complementary oligomer blend,
(iii) a permeation enhancer, and
(iv) a locally active agent.
2. The delivery system of claim 1 , wherein the adhesive hydrogel composition is entirely comprised of a continuous hydrophilic phase.
3. The delivery system of claim 1 , wherein the acrylate copolymer is a methacrylic acid-ethyl acrylate copolymer.
4. The delivery system of claim 3 , wherein the copolymer is generally insoluble in aqueous fluids having a pH below 5.5.
5. The delivery system of claim 4 , wherein the copolymer has a ratio of free carboxyl groups to ester groups of about 1:1.
6. The delivery system of claim 1 , wherein the poly(N-vinyl lactam) is polyvinyl pyrrolidone.
7. The delivery system of claim 1 , wherein the molecular weight of the hydrophilic polymer is in a range of approximately 500,000 to 1,500,000 daltons.
8. The delivery system of claim 1 , wherein the polyalkylene glycol is polyethylene glycol.
9. The delivery system of claim 1 , wherein the hydrophilic polymer-complementary oligomer blend represents about 17.5 weight percent to about 45 weight percent of the hydrogel composition.
10. The delivery system of claim 1 , wherein the permeation enhancer is selected from the group consisting of sulfoxides, ethers, surfactants, alcohols, fatty acids, fatty acid esters, polyols, amides, terpenes, akanones, and organic acids.
11. The delivery system of claim 1 , wherein the hydrogel composition comprises one or more additional additives.
12. The delivery system of claim 11 , wherein the one or more additives comprises an antimicrobial agent.
13. The delivery system of claim 12 , wherein the antimicrobial agent is selected from methyl paraben, propyl paraben, sodium benzoate, sorbic acid, imidurea, and combinations thereof.
14. The delivery system of claim 1 , wherein the delivery system is monolithic.
15. The delivery system of claim 1 , wherein the locally active agent is a cosmeceutical.
16. The delivery system of claim 2 , comprising an additional low molecular weight plasticizer in addition to the complementary oligomer.
17. The delivery system of claim 1 , further comprising a disposable release liner covering the adhesive hydrogel composition of the body-surface contacting layer.