Elimination of azlocillin in patients with biliary t-tube drainage

The pharmacokinetic of azlocillin was followed in five elderly patients after biliary surgery. Total clearance was 138.6 +/- 17.7 ml/min when 2.0 g was given as an i.v. bolus injection. The half-life of the beta-phase averaged 110 min. The total clearance and the half-life of azlocillin were influenced by slight impairment of renal function (creatinine clearance 59.4 +/- 13.6 ml/min). In patients with normal liver function biliary excretion of the drug amounted to 5.3 +/- 2.8% of the dose (n = 3) and the kinetics of biliary excretion were linear. In contrast, in two patients with impaired liver function biliary excretion was 0.2% and 0.5% of the dose, and kinetic analysis of biliary excretion rates revealed at least one zero order step in the excretion process. Renal excretion of the drug amounted to 45.0 +/- 17.7% of the dose, which means that 50% of the total clearance of azlocillin has to be accounted for by metabolic clearance.