Table 2.

Process parameters in milling and their typical impact on final product properties. It should be noticed that normally, several parameters are affecting milling process and the effect of one parameter on the final product properties is not always clear.

Parameter	Comments
Milling time	Commonly longer milling times lead to more monodisperse particles and decreased particle sizes; however, too long milling times may cause aggregation
Milling speed	Higher milling speed typically increase the milling rate and lead smaller particle sizes
Milling medium (bead size and the amount of beads)	Typically smaller beads lead to smaller nanocrystals; higher amount of beads improve the milling efficiency, though too high bead amount increase contamination
Drug amount	Very small drug amount increases contamination and lowers milling efficiency; very high drug amount increases viscosity and decreases milling efficiency
Milling design	Parameters can change a lot between different milling design: important especially in scaling-up/scaling-down