abstract |
A linear polymer is obtained by reacting together a polyethylene glycol or polypropylene glycol; a PEG-PPG-PEG or PPG-PEG-PPG block copolymer; a difunctional amine or diol; and a diisocyanate. A controlled release composition comprises the polymer together with an active agent. Active agents of molecular weight 200 to 20,000 may be used. |