| abstract |
A process for producing a lactic acid polymer which has a weight-average molecular weight of 15,000 to 50,000 and in which the content of polymeric components having a weight-average molecular weight of about 5,000 or lower is about 5 wt.% or lower, characterized by hydrolyzing a high-molecular lactic acid polymer, allowing the resultant solution containing the hydrolyzates to stand under such conditions that the target lactic acid polymer contained therein can precipitate, and isolating the precipitate. The lactic acid polymer is useful as a base for sustained-release drugs which sufficiently inhibits microcapsules containing a physiologically active substance from excesssively releasing the physiologically active substance in an initial stage and can stably maintain a rate of its release over long. |