Identification of degradation products in a phenylbutazone tablet formulation

Two previously reported but unidentified phenylburazone degradation products were isolated from a tablet that was stored at 60 degrees for 203 days. The compounds, alpha-(N-phenylcarbamoyl)-N-caproylhydrazobenzene and alpha-hydroxy-alpha-(N-phenylcarbamoyl)-N-caproylhydrazobenzene, were isolated by chromatography, identified by mass and NMR spectrometry, and synthesized by the reaction of aniline with phenylbutazone or its hydroxy analog, respectively.