COMPARISON BETWEEN A GRAVITY FEED EXTRUDER AND A TWIN-SCREW EXTRUDER

Extrusion forces and power consumption were measured for binary mixtures microcrystalline cellulose/water and ternary mixtures microcrystalline cellulose/drug substitute/water on a gravity feed extruder and a twin screw extruder, respectively. Ternary diagrams were constructed for mixtures microcrystalline cellulose/dicalcium phosphate dihydrate/water determining the regions where good quality spheres were obtained. This region was much smaller for the twin screw extruder in comparison with the gravity feed extruder and was correlated with differences in the die design of the extruders. Likewise profiles for the amount of water vs extrusion forces and power consumption were obtained in the case of binary mixtures microcrystalline cellulose/water. In the case of ternary mixtures drug substitute/microcrystalline cellulose/water likewise profiles for the amount of drug substitute vs extrusion forces and power consumption were obtained for dicalcium phosphate dihydrate as drug substitute. In the case of the more soluble drug substitutes (alpha-lactose monohydrate and anhydric beta-lactose) differences in profile of the amount of drug substitute vs extrusion forces or power consumption were obtained and were correlated with differences in the die design of the different extruders.