Excretion of 14 C-edrophonium and its metabolites in bile: role of the liver cell and the peribiliary vascular plexus.

1. The metabolism and biliary excretion of (14)C-edrophonium chloride was studied in Wistar rat.2. Approximately 5% of the dose was recovered from bile in 6 hours. Most of the radioactivity was eliminated as (14)C-edrophonium glucuronide. Small amounts of the unchanged drug were also detected in bile, particularly during the first hour after administration of the drug.3. The concentration of (14)C-edrophonium glucuronide in bile was approximately 15-20 times its concentration in plasma.4. In contrast, the concentration of unchanged (14)C-edrophonium was similar in bile and plasma.5. Evidence is presented that unchanged (14)C-edrophonium is transferred from plasma to bile via the peribiliary vascular plexus.