Influence of colloidal silicon dioxide-magnesium stearate interaction on flow and compaction behavior of an MCC-Lactose binary mixture

The amount of glidant and lubricant in a tablet formulation is driven by their primary functionalities of enhancing flowability and reducing particle-wall friction. However, their interaction can lead to undesirable outcomes. This study has examined the influence of this interaction on powder flow and compaction, using colloidal silicon dioxide as a glidant and magnesium stearate as a lubricant in a 50:50 w/w MCC:Lactose binary blend. The findings suggest that nano-sized CSD particles coat other particles in a blend. However, increasing CSD decreases exposed MgSt and reduces its lubricity, resulting in intriguing powder flow and compaction phenomena. CSD impacts powder flow more than MgSt. Increasing the CSD reduces exposed MgSt and increases particle-wall adhesion. Higher CSD concentrations decreased powder bed bulk density and permeability due to the formation of porous structures on primary host particles. A complex interplay between CSD and MgSt during tablet compaction affected tensile strength. CSD promoted tablet picking due to reduced exposed MgSt and increased tablet-punch adhesion. This is the first study correlating tablet picking with take-off force, and it was found that >5 N take-off force risked picking. Ejection force increased with CSD and decreased with MgSt, reaffirming CSD's impact on particle-wall adhesion.