The invention relates to an injectable pharmaceutical composition comprising: (a) a drug substance (b) a polyethylene glycol and (c) a biocompatible and bioerodable poly(DL-lactide-glycolide) (PLGA) polymer (d) wherein the polyethylene glycol serves as a solvent for the PLGA polymer and (e) wherein the composition forms a gel phase when said composition comes into contact with water or bodily fluids.