The drop in MD is accompanied with the improving micro-uniformi-
ty through the mixing process that is evidenced by the declining RSDS as
shown in Fig. 4. Blend 1 was heterogeneous at the micro-scale with RSDS
between 18.9% and 39.3% across the three batches, in line with the
macro-heterogeneity shown in MDs. In contrast, blends 2 and 3 were
homogeneous at the micro-scale (RSDS of b4.7%), regardless of sampling
location and target concentration of API X. This suggests that uniformity
at the micro-scale was attained via the extensive local shear exerted
during the comilling step. There was no improvement in micro-scale
homogeneity between blends 2 and 3, suggesting that maximum
micro-mixing was achieved at the comilling step and the second blend-
ing step did not extend micro-mixing further.