Provided is a biodegradable drug delivery composition comprising: (i) a mixture of at least three different block copolymers, wherein each block copolymer is: (a) a biodegradable triblock copolymer having the formula: Av-Bw-Ax wherein A is a polyester and B is polyethylene glycol and v and x are from 1 to 3,000 and w is from 3 to 300 and v=x or v≠x; or (b) a biodegradable diblock copolymer having the formula: Cy-Az wherein A is a polyester and C is an end-capped polyethylene glycol and y=2 to 250 and z=1 to 3,000; and wherein the mixture comprises at least one (a) and at least one (b); and the weight ratio between (a) and (b) is 1:19 to 5:1; and for at least one of the copolymers according to (a) or (b) A is poly(lactic-co-glycolic acid) (PLGA); and (ii) at least one pharmaceutically active ingredient.