Patent ID: 8163307

Claim:
A method for the preparation of a pharmaceutical composition comprising microparticles including one or more active compounds selected from the group of interferons and one or more biodegradable block copolymers constructed from poly(ethylene glycol) terephthalate (PEGT) and poly(butylene terephthalate) (PBT), wherein the average molecular weight of the polyethylene glycol (PEG) is from about 1,000 to about 2,000 daltons, wherein the block copolymer comprises from about 50 to about 95 wt.% PEGT, and wherein the composition comprises a dose of at least 20 MIU of interferon that is released over a period of about 10 days to about 1 month, comprising the steps of: (a) preparing an emulsion comprising (aa) an aqueous inner phase comprising the one or more active compounds, and (ab) an organic outer phase comprising the one or more biodegradable block copolymer and at least one organic solvent; (b) solidifying the one or more biodegradable block copolymer into microparticles by removing at least a fraction of the organic solvent from the emulsion prepared in step (a); (c) collecting and drying the microparticles formed in step (b) wherein step (b) is carried out by emulsifying the emulsion prepared in step (a) in a coherent aqueous phase to obtain a w/o/w-double emulsion, wherein the coherent aqueous phase comprises an osmotic agent, wherein the osmolality of the coherent aqueous phase is higher than that of the aqueous inner phase.