Is biliary excretion of paracetamol significant in man?

The extent of biliary excretion of paracetamol and its principal metabolites was studied in 10 healthy adults. Duodenal intubation was performed approximately 12 h after an oral dose of 1 g paracetamol. Duodenal fluid was aspirated following intravenous cholecystokinin, and urine was collected for 12 h after dosing. The mean concentration of the cysteine and glucuronide conjugates in the bile was 253.7 +/- 39.0 micrograms ml-1 (s.e. mean) and 69.3 +/- 15.3 micrograms ml-1, respectively. The mean recoveries of the cysteine and glucuronide conjugates in the bile were 6.0 +/- 1.5 mg and 1.2 +/- 0.41 mg, respectively. The bile is an important route of elimination for the cysteine conjugate and accounts for 19.4 +/- 4.4% of the total excretion of the metabolite. The fate of the biliary excreted conjugates is not known, and needs further investigation.