Investigation of the Influence of Continuous Blending Process Parameters on the Lubrication of Pharmaceutical Powder Blends

The lubrication of blends of pharmaceutical powders containing 1% magnesium stearate was evaluated in a continuous blender across a broad range of mass flow rates and blender speeds. Significant changes in both the bulk density and tensile strength of powder compacts were observed as a function of blending conditions. The results demonstrate that for a given blender configuration, various final degrees of blend lubrication can be achieved. An optimal combination of mass flow rate and blender speed for maximum lubrication is found to reside at intermediate process values, consistent with results from other studies. The relationship between blending conditions and blend lubrication state are subsequently described by a numerical model, which describes changes in final blend attributes as a function of key blending process parameters. This model, however, collapses at higher blender speeds, where powder conveyance dominates and mixing dynamics are significantly diminished.