Abstract
A model system consisting of lactose-cornstarch was used to examine the effect of five cellulosic binders [hydroxypropylcellulose (HPC) (6 cP), hydroxypropylmethylcellulose 2910 (HPMC) (3, 6, 15 cP) and methylcellulose (MC) (15 cP)] on the particle size distribution of granules prepared in a fluidized bed under fixed operating conditions. The distribution of binder in different size fractions of granules was also determined by measuring the contents of methoxyl and hydroxypropoxyl groups. When the binders were added by the solution method, higher solution viscosity resulted in the granule size being increased without any increase in the percentage of coarse (>500 μm) particles generated. The granules prepared by the dry mixing method with HPC (6 cP) or HPMC (3 cP) also showed a good correlation between median particle size and binder level. The other binders did not show such a correlation, as higher concentrations of the binders were present in the medium-sized particle fractions of the granules at higher binder levels, and partly aggregated was the observed binder in these granules. The results support our previous conclusion, in a study of wet granulation with a high-speed mixer, that analysis of granule size dependency of binder content is useful for evaluating the effectiveness of binders added by dry mixing.
