Physical characterization of two oxyphenbutazone pseudopolymorphs.

Two pseudopolymorphic forms of oxyphenbutazone, a benzene solvate (Solvate B) and a cyclohexane solvate (Solvate C), were prepared by recrystallization from benzene and cyclohexane, respectively. The forms were characterized by means of differential scanning calorimetry, thermogravimetry, infrared spectrophotometry, X-ray powder diffraction, and thermomicroscopy, as well as powder and intrinsic dissolution rates. The dissolution rates of the two pseudopolymorphs were shown to be superior to those of the anhydrate, hemihydrate, and monohydrate which were previously reported. A brief stability report is included.