Comparative Tableting and Microstructural Properties of a New Starch for Direct Compression

Abstract

A new directly compressible starch for direct compression marketed as Sepistab® St 200 has been studied in relation with the classical variety for direct compression—Sta Rx® 1500. Flowability of Sta Rx was in general higher. Sepistab showed a weight mean diameter two times higher than Sta Rx. Particle size of Sepistab demonstrated a better fitting to normal distribution. No differences of note were observed in the consolidation mechanism on the basis of the tablet-in-die Heckel method. Binding properties and plasticity of Sepistab were higher. Sta Rx showed more interparticulate and die wall friction during compression. Disintegration of the tablets was absolutely different. Sta Rx showed swelling of the tablet with gel formation and longer disintegration times. On the contrary, Sepistab showed almost immediate disintegration. This different behavior can be partially explained on the basis of the content of amylose as effective disintegrating agent. The microstructure of the tablets was measured by mercury porosimetry. The parameters calculated were the total porosity, median size of pore expressed as radius, and surface area of pores, assuming cylindrical pores. The microstructure of tablets of Sepsitab—with higher porosity, surface area of pores, and median pore radius-can also enhance the water penetration and disintegration of the tablet by breaking the hydrogen bonding which is formed during compression and suddenly released in the presence of water.