Granulation and tabletization of pharmaceutical lactose granules prepared by a top-sprayed fluidized bed granulator

Influence of fluidizing air velocity, temperature and atomizing air pressure, as well as types of raw materials on the size distribution, shape and flow properties of pharmaceutical granules, which were tabletized using a single punch tableting machine, was experimentally investigated. The granules prepared at the fluidizing air velocity of 0.8 m/s had average particle size larger than those obtained at higher air velocity. Meanwhile the fluidizing air temperature had moderate effect on the average particle size of the granules. However, an increase in the atomizing air pressure resulted in an increase in amount of fine particles, leading to the smaller mean particle size. From microscopic analysis, a primary lactose particle wetted by binder had several contact points with other particles inside the prepared granules. Based on granule morphology, it can be implied that the granules are formed by the so-called snowballing mechanism, leading to the relatively spherical structure. In tabletization, the granules with higher average particle size provided tablets with the less weight variation and friability. Meanwhile, the tablets produced from lactose–corn starch mixture had shorter disintegration time than those of lactose powder only.