The following metrics were used to characterize the homogeneity of
the blends:
1) The maximum difference (MD) in the average potency of API X
among samples taken from multiple locations of the powder bed
from the same process step, which is shown in Eq. (1)
MD ¼ Max Xi
−Min Xi
ð1Þ
where Xi is the average potency at a specific location i. If samples are
taken only from the top and bottom of the bin blender (68 L),
MD ¼ XT−XB
ð2Þ
where XT and XB stand for the average potency of the sample from
the top and bottom of the bin blender, respectively. MD indicates
the macro-mixing behavior and is expected to be close to zero for