The present invention provides a biodegradable drug delivery composition comprising a mixture of at least two block copolymers taken among triblock and diblock copolymers comprising: (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; (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 and z are the number of repeat units with y=2 to 250 and z=1 to 3,000; wherein 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(ε-caprolactone-co-lactide); and (c) at least one pharmaceutically active ingredient.