*3.4. Stability Test*

Moisture and high temperatures may cause the transformation of drug crystal forms and degradation, especially for solvates. Thus, close attention was paid to their stability under high humidity and high temperatures in this work. Figure 8 illustrates that the ARI-SAL salt was stable, while the ARI-ADI salt acetone hemisolvate was unstable under a high temperature. There were significant differences at the two-theta range of 19◦ to 27◦ compared with the starting PXRD pattern. In conjunction with DSC patterns of ARI-ADI salt acetone hemisolvate, we speculated that desolvation occurred under high temperatures. Unexpectedly, the PXRD pattern of the ARI-ADI salt was inconsistent with that of its acetone hemisolvate under high temperatures, demonstrating that ARI-ADI salt might be unstable under high temperatures.

**Figure 8.** Results of stability testing of ARI-SAL salt (**i**) and ARI-ADI salt acetone hemisolvate (**ii**).
