Abstract: The invention concerns a method for preparing a pharmaceutical composition in the form of microspheres with prolonged release of a water-soluble active principle. The invention is characterized in that it comprises the following successive steps: dissolving an active principle in an appropriate amount of water; emulsifying the resulting aqueous solution of active principle with a d,l-lactide-co-glycolide matrix copolymer, of average molecular weight ranging between 40000 and 80000, dissolved in a chlorinated hydrocarbon, resulting in a first microfine and homogeneous emulsion; emulsifying said resulting first emulsion in an external aqueous phase, containing a surfactant, a viscosity-enhancing agent and an osmotic agent; extraction-evaporation of the solvent to obtain microspheres which are recuperated after filtering, washing and drying.

Abstract: Method for the preparation of a pharmaceutical composition in the form of microspheres controllably releasing at least one water-soluble active ingredient. The method comprises the steps of dissolving the active ingredient in a suitable quantity of water, emulsifying the aqueous solution containing the active ingredient with a solution of at least a dl-lactide-co-glycolide-type matrix copolymer in chlorinated hydrocarbon also containing a low molecular weight polyactide release-modulating agent, which results in a first microfine and homogeneous emulsion; emulsifying the first emulsion thus obtained in an external aqueous phase containing a surface active agent; and removing and evaporating the solvent to produce microspheres which are recovered after filtering, washing, and drying. The microspheres themselves.