Effects of biliary obstruction on the penetration of ciprofloxacin and cefotaxime.

Objective: To evaluate the biliary penetration of ciprofloxacin and cefotaxime in patients with obstructed bile ducts and to determine simple predictive markers of effective biliary concentrations of these drugs.

Methods: Sixty-two patients treated with endoscopic biliary drainage were prospectively included in a nonrandomized way and received intravenous ciprofloxacin (200 mg twice daily) or cefotaxime (1 g three times a day) for more than 24 h before exploration. Blood and bile samples were collected at the time of drainage. Ciprofloxacin and cefotaxime concentrations were measured using high-performance liquid chromatography. Biliary penetration was assessed by the bile-to-plasma ratio of the concentrations of both antibiotics.

Results: Biliary penetration ranged from 0.06 to 42.7 for ciprofloxacin and from 0.01 to 1.14 for cefotaxime. The ratio was more than one in only 10 patients (35%) and three patients (9%) in ciprofloxacin and cefotaxime groups, respectively. Biliary concentration of the drug was more than 10 times the minimal inhibitory concentration in only 10 patients (35%) and in 12 patients (35%) in ciprofloxacin and cefotaxime groups, respectively. Serum bilirubin, alkaline phosphatase or gamma-glutamyl-transpeptidase were not good predictive markers of the biliary diffusion of the antibiotics.

Conclusion: In patients with obstructed bile ducts, the biliary penetration of ciprofloxacin is poor and reaches effective biliary concentrations in a minority of patients. Cefotaxime biliary penetration is even poorer. No liver test can predict accurately the biliary penetration of the drugs.