Solvates of zafirlukast

Area of Science:

• Crystallography
• Materials Science
• Chemical Physics

Background:

• Zafirlukast is a leukotriene receptor antagonist used for asthma treatment.
• Understanding the solid-state forms of pharmaceuticals is crucial for formulation and stability.
• Solvates represent different crystalline forms that can impact drug properties.

Purpose of the Study:

• To elucidate the crystal structures of zafirlukast monohydrate, methanol solvate, and ethanol solvate.
• To investigate the conformational behavior of zafirlukast in different solvated forms.
• To analyze the intermolecular interactions and packing arrangements within these crystal structures.

Main Methods:

• Single-crystal X-ray diffraction analysis was employed to determine the crystal structures.
• The crystal systems and unit cell parameters were identified for each solvate.
• Hydrogen bonding networks and molecular conformations were analyzed.

Main Results:

• Three solvates of zafirlukast (monohydrate, methanol, and ethanol) were successfully crystallized and analyzed.
• All solvates crystallize in the monoclinic crystal system, exhibiting a similar Z-shaped conformation for zafirlukast.
• The methanol and ethanol solvates are isostructural, with distinct hydrogen bonding patterns involving solvent molecules and zafirlukast.
• Solvent molecules are thermally stable below the melting points of the respective solvates.

Conclusions:

• The crystal structure determination provides detailed insights into the solid-state behavior of zafirlukast solvates.
• The observed Z-shaped conformation is consistent across different solvated forms.
• The hydrogen bonding interactions play a significant role in the crystal packing and stability of zafirlukast solvates.