이중 유제 방법으로 제조된 PLG A 미립자들과 반구체:특성과라니티딘(ranitidine)의 방출 양상

PLGA micro/nano particles encapsulating ranitidine as a hydrophilic model drug were prepared by the double-emulsion solvent evaporation method. Surface morphology investigation by scanning electron microscope (SEM) showed that the emulsification by sonication could produce nanoparticles, whereas microparticles were prepared using high speed homogenizer. Moreover, while nanohalf-shell structure instead of spherical nanoparticle could be produced by adding poloxamer into oil phase (MC) with PLGA 504H, the addition of poloxamer didn't change particle shape in case of PLGA 502H. On the other hand, microparticle with poloxamer had more surface pores than those without poloxamer. The size and polydispersity (PDI) of particles were determined by particle size analyzer. Effective diameters of particles were in the range of 400 ~ 800 nm and 1200 ~ 3300 nm in case of nanoparticles and microparticles, respectively. Encapsulation efficiencies were in the range of 1.2 ~ 2.9%. The addition of poloxamer produced the particles with higher encapsulation efficiency. In vitro release study in phosphate buffer (pH 7.4) at 37oC showed common large initial burst release. However, the relative slower release profile could be observed in case of microparticles. Poloxamer addition increased the release rate, which was thought to be related to the increased surface area of particles.