The isolation, identification and structure of a new hydroxylated metabolite of benzbromarone in man.

1. The metabolic fate of the uricosuric drug, benzbromarone, in man was reinvestigated. Plasma and urine samples obtained from healthy subjects after administration of a single oral dose of 100 mg were analysed by h.p.l.c. and g.l.c.-mass spectrometry; bromobenzarone and benzarone, previously assumed to be the debrominated metabolites of benzbromarone, were not detectable. 2. Instead, two metabolites (M1 and M2) were present in plasma samples, which had plasma elimination rates lower than those of the parent drug. 3. One of the metabolites (M1) was identified as 1'-hydroxy-benzbromarone using g.l.c.-mass spectrometric analysis of trimethylsilylated and methylated extracts. Chromatographic and spectroscopic data for this metabolite were identical to those of the synthetic compound.