目的 制备美托拉宗缓释片并探讨其释药机制。方法 从处方和工艺两个方面考察了各因素对药物释放行为的影响。在单因素考察的基础上，采用羟丙甲基纤维素（HPMC） 4000 cps作为骨架材料 HPMC 5 cps作为致孔剂，制备美托拉宗缓释片。通过正交设计，以2、4、7 h的药物释放度为评价指标，优化最佳处方。结果 HPMC的用量和比例对美托拉宗缓释片的释放影响最大。该制剂的体外释放与Ritger-Peppas方程拟合的相关性最好，释药过程为扩散和溶蚀并存。结论 美托拉宗缓释片的工艺重现性好，体外释放符合拟定的释药速率。

Objective To prepare Metlazone Sustained Release Tablets, and study their release mechanisms. Methods The effects of many factors, including formulation and technique on the release behavior of Metlazone Sustained Release Tablets were investigated. Based on the comprehensive single-factor tests, Metlazone Sustained Release Tablets were prepared with HPMC 4000 cps as matrix material, and HPMC 5 cps as porogen. The formulations were optimized by orthogonal design with the accumulative release amounts of 2, 4, and 7 h has the evaluation target. Results The amounts and proportions of HPMC were major factors on release of Metlazone Sustained Release Tablets . The release behaviors of tablets followed Ritger-Peppas kinetics, and the drug was released by diffusion and corrosion mechanism. Conclusion The preparations of Metlazone Sustained Release Tablets has good repeatability and the release in vitro could meet the requirements.