Improving Scale-up of Powder Mixing in the Pharmaceutical Industry

Mixing lactose with a small percentage of red iron oxide causes the blend to change from white to pink -> red -> orange. This colour change occurs in different types of mixers but reaching the equivalent blend colour depends on the speed and time (for e.g. 60 minutes in a tumbler mixer is equivalent to 10 minutes in a high shear mixer). This thesis tested this colour change with other common pharmaceutical powders and different iron oxides, and investigated whether the equivalent blend colour could determine the mixing point (time) for an asthma inhaler formulation involving different mixers.