Solvates of zafirlukast.

The crystal structures of three solvates of zafirlukast [systematic name: cyclopentyl N-{1-methyl-3-[2-methyl-4-(o-tolylsul-fonylaminocarbonyl)benzyl]-1H-indol-5-yl}carbamate], viz. the monohydrate, C₃₁H₃₃N3O₆S·H₂O, (I), the methanol solvate, C₃₁H₃₃N₃O₆S·CH₃OH, (II), and the ethanol solvate, C₃₁H₃₃N₃O₆S·C₂H₅OH, (III), have been determined by single-crystal X-ray diffraction analysis. All three compounds crystallize in the monoclinic crystal system. Zafirlukast adopts a similar Z-shaped conformation in all three solvates. The r methanol and ethanol solvates are isostructural. The packing of the zafirlukast molecules in all three crystal structures is similar and is expressed by hydrogen-bonded molecules that are related by translation, along (101) in (I) and along the b axis in (II) and (III). The methanol and ethanol solvent molecules are hydrogen bonded to two molecules of zafirlukast. The water molecule, on the other hand, acts as a connector via hydrogen bonds between three molecules of zafirlukast. The solvent molecules are not released at temperatures below the melting points of the solvates. [ABSTRACT FROM AUTHOR]