From our observations, there is approximately a 50 MPa difference between the point where a change in the distribution of Form I is evident, and the phase transition pressure of glycolide under hydrostatic conditions. For a pure glycolide compact, we would anticipate a lower phase transition pressure upon compaction, given the reduced size of glycolide particles and the increase in shear stress upon anisotropic compression. Thakral et al observed that when chlorpropamide in a blend with a significant MCC content (50:50 wt%), the presence of MCC reduced the extent of transformation between polymorphs. Though the reduction observed in the Thakral study was subtle, we report a more pronounced impact of the formulation on transformation pressure as it contains a higher MCC content (80% wt). Li et al. have also shown that magnesium stearate presence in blends can also alter the compaction pressure required to induce a phase transformation. One of the key observations of this study is that the retention of Form II on decompression has enabled us to observe the impact of pressure on the system without the destruction of the tablet. Form II is still the thermodynamically less stable form under ambient conditions, hence there is a driving force to transform back to Form I. The local environment, i.e. whether it is in the center or the edge of the tablet, will play a role in the kinetics of the transition and we observed this in the image of Form I around the edge at 211 MPa. Those crystallites at the edges of the tablet are much more likely to convert to Form I due to the interaction with moisture in the air and also through shear force interaction with the die holder of the tablet press. Both of these interactions can facilitate the transition back to the ambient form. The Form I to Form II transition is reconstructive where bigger particles are broken up into smaller particles , even if micron sized. A result of this is that the powder produced should become a "better" powder for X-ray diffraction by reducing any preferred orientation that may be present initially. Both of these factors aid the analysis using XRD-CT as there is less requirement to filter out single crystal diffraction providing a more optimal reconstruction of the image (for details see the SI). We observe this through a reduced number of single crystal particles around the edges of the tablet and the increased resolution of the border around the edge of the tablet as increasing compaction pressure is used.