RESUMEN
<p><b>OBJECTIVE</b>To prepare sustained-release microsphere containing extract of Sanguis Draconis and to measure its dissolution in vitro.</p><p><b>METHOD</b>Sustained-release microsphere was prepared with polylactic acid (PLA) as carriers using the oil-in-water (O/W) emulsion solvent evaporation method. The powder particle's characteristics of sustainded-release microsphere were evaluated comprehensively, and its dissolution characteristics in vitro were studied.</p><p><b>RESULT</b>The microsphere was round and its surface was smooth, drug-loading rate was 21.97% and the entrapment rate was 55.76%, the accumulative release percentage was 76. 71% in 16 hours.</p><p><b>CONCLUSION</b>The sustained release effect of Sanguis Draconis microspheres was formed with potentially wide applications.</p>