Fine particle comprising biodegradable polymer, medicine containing the particle and production of the particle and the medicine

PURPOSE: To obtain fine particles comprising a biodegradable polymer useful as an ultrasonic contrast, composed of a polymerizable aldehyde, a gas and/or a readily volatile liquid and a binder, having a narrow particle size distribution. CONSTITUTION: The biodegradable particles comprise (A) a polymerizable aldehyde such as crotonaldehyde, a methylaldehyde or glutaraldehyde optionally containing a copolymerizable additive and/or a cross-linking agent, (B) optionally a surfactant (mixture), preferably polyglutaraldehyde hydrogensulfite-sodium, (C) a gas and/or a readily volatile liquid, preferably air, argon or propane, (D) a binder such as hydroxylamine, aminomannitol or urea and optionally (E) a biomolecule or a polymer (e.g. an organ or tissue specific compound such a monoclonal antibody) bonded through the component D and a diagnostically or therapeutically active ingredient (e.g. doxorubicin, magnetite and mitomycin C to tumors).