盐酸四环素/α-TCP骨水泥载药体系的体外释放研究

对盐酸四环素/磷酸钙骨水泥药物释放体系进行了体外释放研究。XRD分析结果表明，一定含量的盐酸四环素的存在不会影响α-TCP的水化。在体外释放实验中，各种药物含量的载药体系均表现出了良好的缓释性能，持续释放时间超过1200h；由于盐酸四环素同磷酸钙的吸附与结合，当药物在体系中的含量发生改变时，释放控制机理发生改变。当抗生素在固相中含量较大时，药物释放速率以扩散控制为主。药物释放量满足时间平方根关系；当药物含量较低时，在释放前期，药物释放速率仍然以扩散控制为主；释放后期、药物分子从磷酸钙表面的解脱溶出与扩散对药物释放形成混合控制。

In Vtro Release of Tetracycline Hydrochloride from α-TCP Cement

Drug release from alpha-TCP cement containing tetracycline hydrochloride (TTCH) was studied in vitro. Results from X-ray diffraction study indicated that TTCH did not prevent the hydration of alpha-TCP. In vitro drug release study showed that TTCH release could sustain over 1200 h, and the release was controlled by two mechanisms: (1) diffusion of free TTCH molecules through the porous cement (square-root-of-time kinetics); (2) dissociation of TTCH from the apatite-TTCH complex (zero-order kinetics). The mechanism controlling release would changed with the variety of the antibiotic content of cement pellets, as a result of TTCH adsorption and bonding on calcium phosphates. The first mechanism was predominantly for low concentration system TTCH-loaded apatite cement systems at the initial release period, and for high concentration TTCH-loaded apatite cement systems. As for low concentration TTCH-loaded apatite cement systems at later release stage, drug release was controlled by the coupling of the two mechanisms.