Effect of Addition Ratio of Silicic Acid Compounds on Flowability of Lactose

Abstract

The control of powder flowability with fine particles is important for tablets prepared by direct compaction. In the present study, the addition ratio of two types of fine particles of silicic acid compounds that can be used as glidants was examined to improve powder flowability. The powder sample, lactose, with a count median diameter (D_P50) of 103 μm, was used as an excipient, while magnesium aluminometasilicate (MA; D_P50 = 1.2 μm) and magnesium silicate (MS; D_P50 = 0.6 μm) were used as glidants. MA or MS was added to the excipient at different ratios in a range from 0.2 to 3.0 mass%. Powder flowability was evaluated by a vibrating tube method, which can characterize both the static and dynamic friction properties, and by conventional methods, i.e., measuring the angle of repose and compressibility. From a series of experiments, it was found that MA is more effective than MS in improving powder flowability, but with a strong dependence of addition ratio.