Effect of Packaging on Stability of Simvastatin Tablets

Three types of packages[polyvinyl chloride(PVC)-aluminum(Al),polyvinyl dichloride(PVDC)-Al and Al-Al blisters]were used to investigate the effect of packaging on stability of moisture sensitive simvastatin tablets.The content changes of simvastatin and its related substances and the container moisture permeability of blisters were studied to evaluate the effects.Three related substances of simvastatin were identified to be simvastatin acid, lovastatin and lovastatin acid by HPLC and LC-MS.The increase of related substances of simvastatin was mainly attributed to the increase of simvastatin acid content,implying that the degradation of simvastatin was primarily caused by hydrolysis.It was proposed that the stability of simvastatin tablets was highly related to the moisture permeability of package.Packages with excellent humidity resistance,such as Al-Al blisters,would be beneficial to improve the stability of simvastatin tablets.