THE EFFECTS OF COMPRESSION RATE AND FORCE ON THE COMPACTION PROPERTIES OF DIFFERENT VISCOSITY GRADES OF HYDROXYPROPYLMETHYLCELLULOSE-2208

The effects of compression speed and force on the compaction propertie s of four viscosity grades of hydroxypropylmethylcellulose 2208 (HPMC K100, HPMC K4M, HPMC K15M, HPMC K100M) have been assessed. The tensile strengths of their tablets, the energies involved in compaction, mean yield pressures, elastic recoveries and the contribution of the elast ic and plastic energies to the gross energies have been evaluated usin g a compaction simulator. For each viscosity grade of HPMC, an increas e in compression speed from 15 to 500 mm/s generally decreased the ten sile strength of the tablets. The tensile strengths of HPMC K100 table ts were more sensitive to changes in compression speed than those of t he other grades. Tablets of HPMC K100 had the highest tensile strength at any compression force or speed. An increase in compression speed f rom 15 to 500 mm/s resulted in an increase in the mean yield pressure of HPMCs. The highest elastic recoveries were found for compacts made at 500 mm/s at each viscosity grade (48.0, 28.1, 49.8 and 50.0% for HP MC K100, HPMC K4M, HPMC K15M and HPMC K100M, respectively). At each co mpression speed, HPMC K4M had the lowest elastic recovery. For each vi scosity grade of HPMC, an increase in compression force from 5 to 10 k N resulted in an increase in elastic recovery; above a force of 10 kN the elastic recovery decreased for each HPMC except HPMC K4M. An incre ase in compression force and speed increased the percentage contributi on of the elastic energies of the gross energies for the different gra des of HPMC. For example, for HPMC K4M the percentage contribution of the elastic energies of the gross energies were 12.4 and 39.9% for com pression forces of 5 and 20 kN, respectively, and for compression spee ds of 15 and 500 mm/s were 16.1 and 34.2%, respectively.