abstract |
[Problem] To provide a sustained release preparation using a biodegradable polymer having sustained release as a base material such as a microcapsule for encapsulating a physiologically active substance, and a method for producing the same. SOLUTION: A bioactive substance can be incorporated at a high content by reducing the content of a low molecular weight lactic acid polymer, particularly a polymer having a weight average molecular weight of 5000 or less, from a biodegradable polymer comprising lactic acid. And the lactic acid polymer which can suppress the initial excessive release, and can implement | achieve the stable release rate over a long period of time, a manufacturing method, and a sustained release formulation using the same. [Selection figure] None |