Isolation and identification of bromfenac glucoside from rat bile

Bromfenac (Duract(R)), a drug approved for pain, was expected to be metabolized by the rat to an acyl glucuronide, a metabolite formed with most compounds of similar structure. During the investigation of metabolite profiles in rat bile following administration of 1 mg/kg iv doses of 14C-bromfenac, an acid-labile metabolite was found that degraded to form 14C-bromfenac. Isolation and characterization of this metabolite indicated that it is an unusual conjugate, bromfenac N-glucoside.