Patent ID: 7135190

Claim:
An aqueous biodegradable polymeric drug delivery composition possessing reverse thermal gelation properties comprised of an aqueous phase having uniformly contained therein: (a) an effective amount of a drug; and (b) a biodegradable polymeric system possessing reverse thermal gelation properties comprising a mixture of at least a Component I triblock copolymer and a Component II triblock copolymer, said triblock copolymers comprising biodegradable polyester A-polymer blocks and polyethylene glycol B-polymer blocks, wherein the B-polymer block of said Component I triblock copolymer has an average molecular weight of 900 to 2000 Daltons and the B-polymer block of said Component II triblock copolymer has an average molecular weight of 600 to 2000 Daltons, and wherein said Component I triblock copolymer has an average molecular weight of between 2500 to 8000 Daltons and said Component II triblock copolymer has an average molecular weight of between 800–7200 Daltons, and wherein said biodegradable polymeric system is water soluble and contains 51 to 83% by weight of hydrophobic A polymer blocks and 17 to 49% by weight of hydrophilic B polymer blocks and wherein an aqueous solution of said Component I triblock copolymer has a lower gelation temperature than an aqueous solution of said Component II triblock copolymer.