Potential use of gelcasting hydroxyapatite porous ceramic as an implantable drug delivery system.

Hydroxyapatite (HA) ceramic in a porous configuration is suggested as a drug release system. A new technique for the production of this material, based on the foaming of suspensions and in situ polymerization (gelcasting method), resulted in a material whose characteristics are likely to make it useful as an implantable drug delivery system. Three batches of HA ceramic with different porosities were characterized by X-ray diffraction and scanning electron microscopy (SEM). Pore size and shape as well as density were determined. In vitro experiments were performed in order to evaluate the dissolution behavior of cisplatin in the system. X-ray diffraction analysis showed that the final product consisted of a single phase, indicating that the sintering process had not affected the structure of the HA. Energy dispersive X-ray analysis (EDX) showed absence of impurities. Pore diameters were in the range 15--34 microm. SEM showed that the material presented a highly interconnected spheroidal porous network with open micropores and closed macropores. In vitro experiments showed significant differences in the release rate of cisplatin between three different porosities.