Stability after ground norfloxacin tablet.

Because a Norfloxacin tablet is often used by grinding although it is film-coated in consideration of stability to moisture absorption and light, its stability, after grinding was determined. Norfloxacin powder prepared by grinding was divided and packed using 2 kinds of powder papers, and then stored under 3 different conditions;they were, prevention of light at room temperature, 30°C and 92% of relative humidity (RH), and exposure to fluorescent light (800 lx) at room temperature. After that, the observation of appearances, the measurement of hygroscopic degree, and the measurement of Norfloxacin content and the identification and quantification of decomposition products by high-performance liquid chromatography were undertaken.As a result, there were no changes when stored under prevention of light at room temperature. On the other hand, the powder became colored and decomposed when stored under exposure to fluorescent light at room temperature, or rapidly lost its fluidity due to moisture absorption when stored under 30°C and 92% RH. These results suggested that we should be careful with moisture absorption and light to store this drug after grinding.