Patent ID: 7678146

Claim:
A bio-stable hydrogel for use as an endoprosthesis in a mammal, said hydrogel, prior to being administered as an endoprosthesis, consisting essentially of: a cross-linked polyacrylamide which includes a cross-linked polymer of acrylamide and methylene bis-acrylamide, wherein the acrylamide and methylene bis-acrylamide are combined in a molar ratio of 150:1 to 1000:1 and wherein the hydrogel comprises about 0.5 to less than 3.5% of the polyacrylamide by weight, based on the total weight of the hydrogel, and water or an aqueous solution, wherein the hydrogel comprises less than 50 ppm of acrylamide and methylene bis-acrylamide monomers; and wherein the hydrogel has an elasticity module from about 10 to 700 Pa and a complex viscosity from about 2 to 60 Pas, wherein the hydrogel is resistant to biological degradation, and wherein the hydrogel is not water-soluble.