Biomaterials Universe, Inc.

Yoshita Ikada

Suong-Hyu Hyon

Microspheres comprising polylactic acid and a water soluble physiologically active substance and having a mean particle size of from about 0.01 .mu.m to 300 .mu.m, which show not more than 30% of an eluted amount of said physiologically active substance based on the content of said physiologically active substance in the polylactic acid type microspheres after 24 hours in in vitro elution test in phosphate buffer of pH 7.4 at 37.degree. C., and a process for preparing the same. The polylactic acid type microspheres of this invention is advantageous in that the active substance can be uniformly incorporated into the microspheres without loss of the activity, can gradually release the active substance for a long time of period of more than one week.

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Uji, Japan

Yoshita Ikada