Patent ID: 8642666

Claim:
A composition comprising: (a) one or more biodegradable block copolymer drug carriers comprising A-B, A-B-A or B-A-B block copolymers having a total weight average molecular weight of 2000 to 4990 Daltons, wherein the A block is a biodegradable polyester or poly(ortho ester) and the B block is polyethylene glycol (PEG), and the weight percentage of the A block is between 51% to 83% and the weight percentage of the B block is between 17% to 49%; and (b) a polyethylene glycol (PEG), a PEG derivative, or a mixture of PEG and a PEG derivative, said PEG or PEG derivative having a molecular weight of 150 to 1100 Daltons, wherein the PEG derivative is an ester derivatized PEG and wherein the PEG is derivatized with D,L-lactide, D-lactide, L-lactide, D,L-lactic acid, D-lactic acid, L-lactic acid, glycolide, glycolic acid, ε-caprolactone, 1,4-dioxan-2-one, ε-hydroxy hexanoic acid, γ-butyrolactone, γ-hydroxy butyric acid, δ-valerolactone, δ-hydroxy valeric acid, hydroxybutyric acids, malic acid, or mixtures thereof; wherein at least one of component (a) is soluble in an aqueous solution and miscible with component (b), the weight ratio of component (a) to component (b) is within the range of 2:1 to 1:99, the composition can be reconstituted in water or an aqueous solution to form a homogeneous solution or a uniform colloidal system, the composition is free of toxic or dangerous organic solvents, and the composition possesses reverse thermal gelation properties such that it forms a gel when reconstituted and administered to a warm blooded mammal.