Disposition and excretion of cefoperazone in rabbits

The pharmacokinetics of cefoperazone were studied after i.v. administration of a single 30 mg/kg dose in a total of 40 New Zealand rabbits. Determination of the plasma levels of the drug revealed a slow elimination half-life of 0.48 h. The disappearance half-life of cefoperazone in interstitial tissue fluid shows a mean value of 1.9 h, being statistically higher than the value found for the half-life of the slow phase of elimination from the systemic circulation. 12 h after i.v. administration, 32.1% of the drug was seen to be excreted by the kidney and a further 15.2% in bile. The urinary excretion constant had a mean value of 0.29 h-1, whereas that of biliary excretion was 0.12 h-1.