Surface engineering to improve the flowability and fluidization of a cohesive powder

Fine pharmaceutical powder formulations must exhibit satisfactory powder flow during production, transportation and administration. We have shown that mechanical co-processing of fine powders with small quantities of magnesium stearate can radically change the behaviour of fine lactose powders. We report investigations of the basic characteristics of such powders, which have undergone mechanofusion with surface modifying additives, and compare these to unmodified powders, and powders subjected to conventional blending. The study looked at both flow characteristics, as well as fluidization behaviours of a model powder, with median diameter of 8A?m. A powder rheometer was used to probe flow and cohesion properties and these analyses are used to improve understanding of formulation performance. This work indicated that a substantial improvement in flow and fluidization behaviours could be achieved for fine lactose powders within the specific size range by appropriate surface modification. In addition, we observed behaviour changes that appear to derive from changes in packing density and inter-particulate cohesion. The observations have significant implications for future formulation optimisation, and support a Quality by Design formulation approach to product development risk management.