Patent ID: 8252275

Claim:
A polymeric reagent of the following formula: wherein: POLY 1 is a first water-soluble polymer selected from the group consisting of poly(alkylene glycol), poly(olefinic alcohol), poly(vinylpyrrolidone), poly(hydroxyalkylmethacrylamide), poly(hydroxyalkylmethacrylate), poly(saccharides), poly(α-hydroxy acid), poly(vinyl alcohol), polyphosphazene, polyoxazoline, and poly(N-acrylmorpholine); POLY 2 is a second water-soluble polymer selected from the group consisting of poly(alkylene glycol), poly(olefinic alcohol), poly(vinylpyrrolidone), poly(hydroxyalkylmethacrylamide), poly(hydroxyalkylmethacrylate), poly(saccharides), poly(α-hydroxy acid), poly(vinyl alcohol), polyphosphazene, polyoxazoline, and poly(N-acrylmorpholine); X 1 is a first spacer moiety; X 2 is a second spacer moiety; H α is an ionizable hydrogen atom; R 1 is H or an organic radical; R 2 is H or an organic radical; and (FG) is a functional group capable of reacting with an amino group of an active agent to form a degradable linkage.