Göpferich A
Department of Pharmaceutical Technology, University of Erlangen-Nürnberg, Germany.
Biomaterials. 1997 Mar;18(5):397-403. doi: 10.1016/s0142-9612(96)00151-2.
The erosion of composite polymer matrices made of slow and fast eroding polymers was investigated. These matrices can be used as implants that release drugs in a preprogrammed way. To understand the mechanism of drug release, the erosion of cylindrical polymer matrices made of several layers of different polymers was investigated. A layer of poly(D,L-lactic acid) was used to separate a core and a mantle consisting of poly(1,3-bis[p-carboxyphenoxy]propane-co-sebacic acid) 20:80. The investigation of the erosion mechanism revealed that erosion is a two-phase process. Wide angle X-ray diffraction and differential scanning calorimetry proved that the crystalline polymer parts of the polyanhydride layers above and below the polylactide erode one after the other. Concomitantly, sebacic acid accumulates periodically inside the matrix and leaves it in two phases. This agrees well with the release of brilliant blue and carboxyfluorescein, two model compounds, from such implants when incorporated into the polyanhydride layers. It can be concluded that the core of the composite implant erodes with a delay of 10-14 days because the polylactide protects it against premature erosion. Theoretical erosion models that were developed to simulate erosion support the proposed mechanism.
研究了由快速和慢速侵蚀聚合物制成的复合聚合物基质的侵蚀情况。这些基质可用作以预编程方式释放药物的植入物。为了解药物释放机制，研究了由几层不同聚合物制成的圆柱形聚合物基质的侵蚀情况。使用一层聚（D，L-乳酸）来分隔由聚（1,3-双[对羧基苯氧基]丙烷-共-癸二酸）20:80组成的芯部和外层。侵蚀机制的研究表明，侵蚀是一个两阶段过程。广角X射线衍射和差示扫描量热法证明，聚乳酸上下的聚酸酐层的结晶聚合物部分相继侵蚀。同时，癸二酸在基质内周期性积累并分两个阶段离开基质。这与两种模型化合物亮蓝和羧基荧光素从掺入聚酸酐层的此类植入物中的释放情况非常吻合。可以得出结论，复合植入物的芯部延迟10 - 14天侵蚀，因为聚乳酸保护其免受过早侵蚀。为模拟侵蚀而开发的理论侵蚀模型支持所提出的机制。
