US Patent 8652506 Bio-degradable block co-polymers for controlled release

A block or graft copolymer includes a first block, and a second block different from the first block, wherein the first block is a poly(lactide-glycolide) copolymer. The polymers may be formulated in compositions with drug components for use in coating medical devices such as stents. Different blocks of the block or graft copolymer degrade in the body at different rates. The drug release profile from the coating is a combination the individual release rates of the different blocks and so can be controlled by controlling the selection and relative amounts of the respective blocks.