The effects of bile duct obstruction on the biliary secretion of ciprofloxacin in piglets.

OBJECTIVE: The aim of this study was to evaluate the effect of bile duct obstruction on biliary secretion of ciprofloxacin and to look for useful parameters to guide clinical use of antibiotics in patients with acute cholangitis. METHODS: Twenty-five Landrace piglets were used in this study. Their common bile ducts were ligated, with a duration ranging from 1 to 7 days. The changes of liver biochemical tests, intrabiliary pressure, diameter of common bile duct, and concentration of ciprofloxacin in bile were compared among the piglets with different severity of bile duct obstruction. RESULTS: The bile-to-serum ratio of the ciprofloxacin concentration was 586.4% +/- 140.3% before the ligation of bile duct and was reduced significantly to 94.5% +/- 118.0% after 1-day obstruction. The biliary secretion of ciprofloxacin was greatly affected by the intrabiliary pressure in that the bile-to-serum ratio of ciprofloxacin concentration was reduced to 12.2% +/- 14.8% when the intrabiliary pressure reached to 32 cm H2O. The change in the intrabiliary pressure was correlated with the diameter of common bile duct, with a correlation coefficient of 0.90 (p < 0.001). CONCLUSIONS: Biliary secretion of ciprofloxacin is decreased in proportion to the increase of intrabiliary pressure. In obstruction, a markedly dilated common bile duct usually indicates high intrabiliary pressure, and thus biliary concentrations of antibiotics will be lower than expected. Hence, our observations suggest that choosing an antibiotic with high antimicrobial activity, or establishing a biliary drainage to lower the intrabiliary pressure, would be beneficial for patients suffering from cholangitis with a dilated biliary tree.