Polymorphism of phenylbutazone: properties and compressional behavior of crystals.

Data from X-ray diffraction, thermal analysis, IR spectroscopy, and solubility studies were used for the identification and characterization of four crystalline modifications of phenylbutazone. The thermal behavior of the polymorphs under different treatment conditions also was investigated. Compression of the thermodynamically unstable forms, at a compression force of 1590--2040 kg, induced polymorphic changes in the crystals.