Polymeric microparticle (I) comprising an active ingredient is claimed. The polymer present in (I) is amphiphilic, biodegradable, hydro-soluble copolymer with hydrophobic and hydrophilic groups, spontaneously forms a colloidal suspension of nanoparticles in water at a pH of 7 under isotonic condition. (I) is non-covalently bonded to the active ingredient and obtained by atomization of a solution or a colloidal suspension of (I), has a size of 0.5-100 mu m, preferably 2-40 mu m and is dispersible in colloidal suspension measured by a dispersibility test described in the given specification. Independent claims are included for: (1) a process of preparing (I) comprising atomizing a solution or a colloidal suspension of (I)； (2) a liquid/solid pharmaceutical formulation for the sustained release of the active ingredient comprising a less viscous colloidal suspension； (3) requirements for a reconstitution process comprising (I) and a reconstituting liquid like an aqueous liquid, water (non)miscible organic liquid； and (4) a reconstitution process comprising mixing and agitating the given requirements.
