Combination of Colloidal Silicon Dioxide with Spray-Dried Solid Dispersion to Facilitate Discharge from an Agitated...

A feasibility evaluation of the addition of fumed silica (SiO₂) into an agitated dryer to aid spray-dried solid dispersion intermediate (SDSDi) flow during secondary drying and discharge is described. The quantity of SiO₂ to enhance the flow character of SDSDi was assessed by measuring particle size distribution, bulk density, and flow-through-an-orifice. Results indicate that the addition of the SiO₂ did not alter the drying kinetics and did not impact the bulk particle size distribution of the SDSDi. While bulk density of SDSDi increased with the addition of SiO₂, the flow, and thus the recovery of the SDSDi-SiO₂ batch from the secondary dryer, was significantly higher than that for the intermediate alone. Imaging indicated uniform distribution of SiO₂ in the bulk powder and coating on intermediate particles. Premixing and co-sieving of the SiO₂ with a portion of pre-dry SDSDi promotes the uniform distribution of SiO₂ within the bulk powder bed.