Effect of granulation process on physicomechanical properties of granules and compaction behaviour of hydroxypropyl methylcellulose with different degrees of methoxy/hydroxypropyl substitution

This study was performed in order to investigate the effect of dry and wet granulation techniques on physicomechanical properties of granules and compression behaviour of HPMC with different degrees of methoxy/hydroxypropyl substitution (HPMC K4M, HPMC E4M and HPMC F4M). The granules were prepared by both wet and dry procedures. Particle size distribution, mechanical properties (crushing strength, yield point and elastic modulus), bulk and tap densities, and the flow rate of granules were investigated. Then the granules and their corresponding powders were tableted at different compaction forces and their crushing strengths were determined. The results showed that granulation process improved flowability of the polymers. However the effect of wet granulation process was more apparent. HPMC K4M exhibited the biggest size and the highest flow rate compared to other grades in both wet and dry granulation procedure. The granules produced by wet granulation were very hard and brittle compared to granules produced by dry method which exhibited plastic properties. Granules prepared from HPMC E4M were softer than other grades. Tablets made fromHPMC powders were significantly harder than those prepared by wet granulation. However dry granulation affected the hardness of the tablets to lesser extent. The following order was found for the hardness of tablets: direct compression>dry granulation>wet granulation. The hardness of tablets prepared from different grades of HPMC exhibited the following trend: HPMC K4M>HPMC F4M>HPMC E4M. The physicomechanical properties of HPMC granules and their compacts were dependent on granulation method and the grade of HPMC used.