Patent ID: 7425581

Claim:
A controlled release system comprising a temperature sensitive polymer having a lower critical solution temperature (LCST) that changes during incubation in an aqueous medium wherein said temperature sensitive polymer consists of (a) a homopolymer formed from monomers consisting of N-(2-hydroxypropyl) methyl acrylamide (lactate) n where n is 1-10 and n is the same in the monomers that constitute said homopolymer, said homopolymer coupled to a hydrophilic block; or (b) an interpolymer formed from monomers consisting of N-(2-hydroxypropyl) methyl acrylamide (lactate) n where n is 1-10 and n varies in the monomers that constitute the interpolymer, said interpolymer optionally coupled to a hydrophilic block; and an active ingredient.