A process for forming microspheres is disclosed. The process includes: forminga firstplurality microspheres comprising at least one bioactive agent and modifiedcellulose; contactingthe first plurality of microspheres with a solution of a biodegradable polymerto form adiscontinuous phase liquid; contacting the discontinuous phase liquid with acontinuous phaseliquid to form an emulsion; and extracting a second plurality ofmicrospheres from theemulsion, the second plurality of microspheres comprising the first pluralityof microspheres.