Biliary excretion of ciprofloxacin and piperacillin in the obstructed biliary tract.

Biliary excretion of ciprofloxacin and piperacillin was determined in cholestatic patients who had undergone endoscopic cholangiography. The median concentration of ciprofloxacin (n = 9) was 2.36 micrograms/ml (range, 0.29 to 19.8 micrograms/ml) in bile compared with 1.66 micrograms/ml (range, 0.73 to 2.69 micrograms/ml) in serum. The median concentration of piperacillin (n = 7) was < 5 micrograms/ml (range, < 5 to 26) in bile compared with 14.3 micrograms/ml (range, 5.3 to 80) in serum. Ciprofloxacin, but not piperacillin, can be actively excreted into bile in the presence of a biliary tract obstruction.