Otsuka M, Matsuda Y, Kokubo T, Yoshihara S, Nakamura T, Yamamuro T
Department of Pharmaceutical Technology, Kobe Pharmaceutical University, Japan.
Biomed Mater Eng. 1993 Winter;3(4):229-36.
A novel device consisting of Eudragit-coated cephalexin as a model drug and a self-setting bioactive cement based upon CaO-SiO2-P2O5 glass was investigated. The glass cement hardened within 5 min of mixing with a phosphate buffer. After setting, in vitro drug release from homogeneous or heterogeneous drug-loaded cement pellets in a simulated body fluid (SBF) at pH 7.25 and 37 degrees C continued for over 2 weeks. The hardened cement gradually formed low-crystallinity hydroxyapatite and decreased in volume by about 5% during drug release in SBF. Consequently, 30% of the loaded drug was initially released from the homogeneous cement system, and thereafter it was released more slowly. Since the heterogeneous system consisting of the cement and a 50% polymer coated, drug-loaded pellet avoided this drug's burst, the drug was released over a longer period than that in the homogeneous system. The heterogeneous system released the polymer-coated drug very slowly, because it completely avoided the initial burst, and sustained the release over a long period.
研究了一种新型装置，该装置由作为模型药物的丙烯酸树脂包衣头孢氨苄和基于CaO-SiO₂-P₂O₅玻璃的自固化生物活性水泥组成。玻璃水泥与磷酸盐缓冲液混合后5分钟内硬化。固化后，在pH 7.25和37℃的模拟体液（SBF）中，均匀或非均匀载药水泥微丸的体外药物释放持续超过2周。在SBF中药物释放过程中，硬化水泥逐渐形成低结晶度羟基磷灰石，体积减少约5%。因此，30%的载药最初从均匀水泥体系中释放，此后释放速度更慢。由于由水泥和50%聚合物包衣的载药微丸组成的非均匀体系避免了这种药物的突释，药物释放时间比均匀体系更长。非均匀体系非常缓慢地释放聚合物包衣药物，因为它完全避免了初始突释，并能长期维持释放。
