Phase Transitions Involving Channel Hydrates of a New Pharmaceutical Compound.

Area of Science:

• Solid-state chemistry
• Pharmaceutical sciences
• Crystallography

Background:

• Pharmaceutical hydrates are common active pharmaceutical ingredients (APIs) due to favorable physicochemical properties.
• While generally safe, hydrates can undergo phase transitions impacting drug substance stability and processability.
• Understanding hydrate behavior is essential for successful drug product development.

Purpose of the Study:

• To investigate the phase transition behaviors of a newly discovered pharmaceutical compound with multiple channel hydrates.
• To analyze the retention and rearrangement of crystal structures during dehydration and rehydration.
• To establish the relationship among different hydrate crystal forms of the new compound.

Main Methods:

• Utilized powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy, and single-crystal X-ray diffraction.
• Examined temperature-induced dehydration and moisture-facilitated rehydration processes.
• Confirmed hydrate structures through single-crystal X-ray diffraction analysis.

Main Results:

• Identified three distinct channel hydrates for the new pharmaceutical compound.
• Observed symmetric lattice relaxation in Hydrate 3 during phase transitions.
• Documented a unique asymmetric lattice relaxation in Hydrate 2 upon dehydration, forming a new unit cell that reverted to Hydrate 2 in the presence of water.

Conclusions:

• Established the relationship between the crystal forms of the new compound's hydrates.
• The findings are vital for drug product risk assessment, aiding in the avoidance of manufacturing and stability challenges.
• This methodology can be applied to other newly discovered active pharmaceutical ingredients (APIs).