Jaraswekin Saowanee, Prakongpan Sompol, Bodmeier Roland
Faculty of Pharmacy, Mahidol University, Sri ayudthaya road, Bangkok 10400, Thailand.
J Microencapsul. 2007 Mar;24(2):117-28. doi: 10.1080/02652040701233655.
The objective of this study was to investigate the effect of poly(lactide-co-glycolide) (PLGA) molecular weight (Resomer RG 502H, RG 503H, and RG 504H) on the release behavior of dexamethasone sodium phosphate-loaded microparticles. The microparticles were prepared by three modifications of the solvent evaporation method (O/W-cosolvent, O/W-dispersion, and W/O/W-methods). The encapsulation efficiency of microparticles prepared by the cosolvent- and W/O/W-methods increased from approximately 50% to >90% upon addition of NaCl to the external aqueous phase, while the dispersion method resulted in lower encapsulation efficiencies. The release of dexamethasone sodium phosphate from PLGA microparticles (>50 microm) was biphasic. The initial burst release correlated well with the porosity of the microparticles, both of which increased with increasing polymer molecular weight (RG 504H > 503H > 502H). The burst was also dependent on the method of preparation and was in the order of dispersion method > WOW method > consolvent method. In contrast to the higher molecular weight PLGA microparticles, the release from RG 502H microparticles prepared by cosolvent method was not affected by volume of organic solvent (1.5-3.0 ml) and drug loading (4-13%). An initial burst of approximately 10% followed by a 5-week sustained release phase was obtained. Microparticles with a size <50 microm released in a triphasic manner; an initial burst was followed by a slow release phase and then by a second burst.
本研究的目的是考察聚（丙交酯-乙交酯）（PLGA）分子量（Resomer RG 502H、RG 503H和RG 504H）对载有地塞米松磷酸钠的微粒释放行为的影响。微粒通过溶剂蒸发法的三种改进方法制备（水包油-共溶剂法、水包油-分散法和复乳法）。当向外部水相中加入氯化钠时，通过共溶剂法和复乳法制备的微粒的包封率从约50%提高到>90%，而分散法导致较低的包封率。地塞米松磷酸钠从PLGA微粒（>50微米）的释放是双相的。初始突释与微粒的孔隙率密切相关，二者均随聚合物分子量的增加而增加（RG 504H > 503H > 502H）。突释还取决于制备方法，顺序为分散法>复乳法>共溶剂法。与较高分子量的PLGA微粒相反，通过共溶剂法制备的RG 502H微粒的释放不受有机溶剂体积（1.5 - 3.0毫升）和药物载量（4 - 13%）的影响。获得了约10%的初始突释，随后是5周的持续释放阶段。尺寸<50微米的微粒以三相方式释放；初始突释后是缓慢释放阶段，然后是第二次突释。
