目的：研究氯化镁缓释片的释放度和相对生物利用度。方法：采用原子吸收分光光度法测定氯化镁缓释片和进口氯化镁缓释片（Slow-Mag）的体内外释放浓度，计算体内外参数，考察氯化镁缓释片的缓释效果，并与Slow-Mag进行对照。结果：氯化镁缓释片体外释放符合Higuchi模型；氯化镁缓释片和Slow-Mag的药时曲线可用二室模型拟合，t_max分别为3.7967h和2.1367h，c_max分别为7.8257μg·ml^-1和8.0254μg·ml^-1，AUC分别为56.5172，34.1971μg·h·ml^-1。结论：氯化镁缓释片对Slow-Mag的相对生物利用度为165.26%，二者为生物不等效制剂。

OBJECTIVE:To study the release property and relative bioavailability of sustained release magnesium cholride tablet(MCST).METHODS:The magnesium concentrations were determined by AAS method.The parameters were calculated and the sustained release effect of MCST was inspected.RESULTS:The release rate of MCST was conformed to Higuchi equation,and the concentration time courves of MCST and Slow Mag were conformed to a two compartment model.The t_max were3.7969 h and 2.1367 h,c_max 7.8257μg·ml^-1and 8.0254μg·ml^-1,AUC 56.5172，34.1971μg·h·ml^-1 respectively.CONCLUSION:The relative bioavailability of MCST was 165.26%,and the two formulations were not bioequivalent.