Sustained-release nanoparticle compositions and methods for using the same

A sustained-release composition in nanoparticle form consisting essentially of a therapeutic agent and a cross-linked copolymer of an N-alkylacrylamide selected from the group consisting of N-methyl-N-n-propylacrylamide, N-methyl-N-isopropylacrylamide, N-propylmethacrylamide, N-isopropylacrylamide, N-N-diethylacrylamide, N-isopropylmethacrylamide, N-cyclopropylacrylamide, N-ethyl-methacrylamide, N-methyl-N-ethylacrylamide, N-cyclopropylmethacrylamide and N-ethylacrylamide, a vinyl monbomer selected from the group consisting of a vinyl alcohol, a vinyl ether, a vinyl ester, vinyl pyrrolidone and a combination of said vinyl monomers, and PEGylated maleic acid conjugate, wherein the weight per weight ratio of the N-alkylacrylamide, vinyl monomer and PEGylated maleic acid conjugate is 70-90:9-20:1-10, said therapeutic agent being encapsulated in said copolymer in an amount from 3% to 10% based on said nanoparticle weight.