Abstract: A method of production of sustained-release microcapsules that comprises obtaining microcapsules comprising a bioactive substance that are encapsulated with a biodegradable polymer, and thermally drying the obtained microcapsules at a temperature not lower than the glass transition temperature of the biodegradable polymer for about 24 to about 120 hours to produce the sustained-release microcapsules comprising, relative to the weight of the sustaind-release microcapsule, not less than 60% (w/w) of the biodegradable polymer, possessing pharmaceutical characteristics clinically excellent in that a bioactive substance is released at constant rate over a very long period of time from just after administration with dramatically suppressed initial release of the bioactive substance in excess just after administration and with minimum remaining organic solvent.

Abstract: A method of production of sustained-release microcapsules that comprises obtaining microcapsules comprising a bioactive substance that are encapsulated with a biodegradable polymer, and thermally drying the obtained microcapsules at a temperature not lower than the glass transition temperature of the biodegradable polymer for about 24 to about 120 hours to produce the sustained-release microcapsules comprising, relative to the weight of the sustained-release microcapsule, not less than 60% (w/w) of the biodegradable polymer, possessing pharmaceutical characteristics clinically excellent in that a bioactive substance is released at constant rate over a very long period of time from just after administration with dramatically suppressed initial release of the bioactive substance in excess just after administration and with minimum remaining organic solvent.