Dehydration behavior and structural characterization of the GW275919X monohydrate

Area of Science:

• Solid-state chemistry
• Crystallography
• Pharmaceutical sciences

Background:

• GW275919X is a central muscle relaxant used for lower back pain.
• The drug exists as a monohydrate, necessitating an understanding of its solid-state properties.

Purpose of the Study:

• To investigate the solid-state dehydration behavior and crystal structure of GW275919X monohydrate.
• To determine the physical stability of the drug based on its solid-state transformations.

Main Methods:

• Thermal analysis (DSC/TGA) and hot-stage powder X-ray diffraction (PXRD) were employed.
• Single crystal X-ray diffraction was used for crystal structure determination.
• Molecular modeling (Cerius²) and BFDH calculations were utilized for visualization and morphology prediction.

Main Results:

• The crystal structure was determined to be monoclinic, space group P21/c, with specific lattice parameters.
• Water molecules are integral to the crystal structure through hydrogen bonding, contributing to its coherence.
• Morphology predictions indicated the longest dimension aligns with the b-direction, matching experimental needle axis observations.

Conclusions:

• The study elucidates the dehydration process and crystal structure of GW275919X monohydrate.
• Hydrogen bonding plays a key role in the stability of the hydrate crystal structure.
• Understanding these solid-state characteristics is vital for the physical stability and formulation of GW275919X.