The layering of active pharmaceutical ingredient (API) suspension on inert carriers through fluid bed granulation has been tackled in several studies. This study investigates the feasibility and impact of aqueous fluid bed granulation of a poorly soluble micronized API suspension directly onto co-processed excipients as active carriers for orally dispersible tablet production. Indomethacin was selected as model API and Parteck ODT® (mannitol based) and StarLac® (lactose-based) were examined as carrier materials. Produced batches were systematically characterized for change in particle size distribution using laser diffraction, flow properties via Hausner ratio determination and morphology using scanning electron microscopy. The solid-state properties were evaluated using differential scanning calorimetry and X-ray powder diffraction (XRPD), and moisture uptake was assessed via dynamic vapour sorption. The initial exposure of the carriers to water induced distinct morphological changes; controlled wetting of Parteck ODT® resulted in particle shrinkage due to surface-confined transient dissolution and subsequent recrystallisation of the mannitol outer layer. On the other hand, wetting the StarLac® caused extensive morphological collapse of it’s spherical structure accompanied with a decrease in all the percentiles of the particle size distribution. Subsequent polymeric processing with hydroxypropyl methyl cellulose solution promoted particle growth and agglomeration for both carriers. Incremental Indomethacin addition further altered the surface, inducing progressive increase in surface roughness, which correlated with diminishing of packing efficiency observed in increase in Hausner ratio, yet all batches remained within passable limits. These findings demonstrate that while aqueous fluid bed layering is a feasible strategy for the solidification of micronized drug suspension onto co-processed excipients, the properties of the product inevitably depend on the inherent properties of the carrier material.
Badawi et al. (Wed,) studied this question.