Biliary elimination of mezlocillin: an experimental and clinical study.

The biliary elimination of mezlocillin, a new semisynthetic penicillin of the acyl-ureido-penicillin group, was investigated in vitro in rabbit liver preparations and in vivo in humans. Experimentally, mezlocillin recovery in the bile during perfusion of isolted rabbit liver (3 h; n = 5) averaged 20.3% of the administrered dose (10 mg). The mean peak concentration in the bile (758 +/- 129.3 micrograms/ml) was reached between 0.5 and 1 h. Biliary clearance was 169 ml/h. In healthy subjects (n = 5), the concentrations of antibiotic measured in the duodenal fluid during a period of 4 h after intravenous administration of 5 g of mezlocillin ranged between 440 and 637 micrograms/ml. In 10 cholecystectomized patients provided with a T-tube, intramuscular injection of 1 g of mezlocillin resulted in a biliary peak concentration of 295.7 +/- 58.1 micrograms/ml. Mean total amount of antibiotic eliminated in the bile over 12 h corresponded to 2.6% of the administered dose. Assays performed during surgery after intravenous administration of 2 g of mezlocillin (n = 10) showed antibiotic activity of 895 +/- 196 micrograms/ml in the common duct bile and 402 +/- 133 micrograms/ml in the gallbladder bile. These data were compared with the values determined for 11 other beta-lactamines studied under identical conditions.