Comparing the dynamic flow properties and compaction properties of pharmaceutical powder mixtures

The dynamic flow properties and compaction characteristics of mannitol and mannitol-sodium carbonate mixtures (80/20, 70/30 and 60/40 by mass) were measured using a Freeman FT4 powder rheometer. The results showed that the mixtures containing up to 30% sodium carbonate had better flow properties and improved compaction characteristics when compared with mannitol alone. The study demonstrated the feasibility of combining a more expensive pharmaceutical excipient with a cheaper ingredient, without compromising desired powder characteristics. It may also provide a useful method for assessing the suitability of new formulations for use as direct compression bases, as part of a wider range of powder flow tests.