abstract |
A water soluble biodegradable ABA- or BAB--type triblock polymer is disclosed that is made up of a major amount of a hydrophobic polymer made up of a poly(lactide-co-glycolide) copolymer or poly(lactide) polymer as the A-blocks and a minor amount of hy-drophilic polyethylene glycol polymer B-block, hav-ing an overall weight average molecular weight of be-tween about 2000 and 4990, and that possesses reverse thermal gelation properties. Effective concentrations of the triblock polymer and a drug may be uniformly contained in an aqueous phase to form a drug deliv-ery composition. The release rate of the drug may be adjusted by changing various parameters such as hydrophobic/hydrophilic component content, polymer concentration, molecular weight and polydispersity of the triblock polymer. Because the triblock polymer is amphiphilic, it functions to increase the solubility and/or stability of drugs in the composition, as demon-strated by a phase diagram illustrating the gelation be-haviour of aqueous solutions of a PLGA-PEG-PLGA triblock copolymer studied at different concentrations and temperatures. |