ABSTRACT
OBJECTIVE: A phenomenon was found that the content of simvastatin decreased after simvastatin tables was strored for a longtime. But few studies focused on drug quality affected by coating. This article designed a series of experiments to explore this phenomenon. METHODS: Acceleration tests were carried out to study the effect of ingredients of coating and solvent on the stability of simvastatin. Furthermore these degradated impurities were isolated and identified. According to the structure of these impurities, mechanism of reactions was speculated. RESULTS: This study revealed that simvastatin seems like to generate simvastatin acid, dehydrated simvastatin, and simvastatin acid esters in contaction with water, ethanol and aluminum oxide, thus water, ethanol and aluminum oxide might be main reasons for degradation of simvastatin tablets. CONCLUSION: The impact of the coating material and coating solvents should be considered carefully during the screening of simvastatin coating materials.