THE INFLUENCE OF LACTOSE PARTICLE-SIZE ON SPHERONIZATION OF EXTRUDATE PROCESSED BY A RAM EXTRUDER

The spheronization of extrudate produced by a ram extruder fitted with either 1.0 or 1.5 mm diameter dies from mixtures of microcrystalline cellulose, lactose (with median diameter of either 18.0 or 117.0-mu-m) and water has been observed. The spherical granules produced have been characterized in terms of their median length (number diameter by microscope) and width (weight diameter by sieving) and the roundness ('One Plane Critical Stability'), width and length (microscope observation) of the most frequently occurring size fraction. Extrudate produced through both 1.0 and 1.5 mm diameter dies with the fine particle size lactose formed granules within 5 min which were well rounded and of a narrow size distribution. Extrudate produced through both the 1.0 and 1.5 mm diameter dies with the coarse grade of lactose, produced spheres, but these were considerably larger in size and had a larger range of size, due to agglomeration of the granules. The changes in shape and size could be observed within the spheronizer by using a photographic technique. The median diameter of spheroids produced by the controlled spheronization of the fine grade lactose mixture was about 1.2 times the diameter of the die producing the extrudate. The median diameter of the spheroids produced by the uncontrolled spheronization of the coarse grade lactose mixture was not related to the die diameter. In fact, extrudate produced from the 1.0 and 1.5 mm dies both produced spheroids of approx. 3.0 mm diameter. The reasons for the difference in processing of the two particle size fractions of lactose appear to be associated with the movement of water in the formulation.