Recirculation of iopanoic acid after conjugation in the liver.

The purpose of the investigation was to determine if an enterohepatic recirculation occurred for the metabolite of iopanoic acid. The major metabolite of iopanoic acid (Telepaque) in dog bile is the glucuronide conjugate. The identification and quantitation of glucuronide conjugate was accomplished by elemental analysis, paper chromatography, thin layer chromatography, fluorescent excitation analysis, and high pressure liquid chromatography. The stability of iopanoic acid glucuronide in refrigerated dog bile was confirmed. Known amounts of the glucuronide conjugate were instilled into the duodenum of 8 awake adult dogs, and bile collected for 8 hours. Between 19% and 53% (average 31%) of the administered dose was recovered in bile, thereby documenting the presence of an enterohepatic recirculation of conjugated iopanoic acid. The slow rise and plateau of the excretion curve suggests that either the compound is absorbed slowly, or that absorption depends upon deconjugation in the gut. The implications are discussed.