Pharmacokinetics of cefoperazone after single and multiple doses.

The pharmacokinetics of cefoperazone was determined following single and multiple intravenous and intramuscular administrations in man. Ten subjects at each dose level were given eleven successive doses, at 12 h intervals of 500 and 1000 mg i.m. and i.v.. Serum concentrations and urinary excretion were determined in all subjects after the first, fifth and eleventh doses. The first i.m. doses yielded mean peak serum levels of 37 micrograms/ml and 76 micrograms/ml at 1.0 h after injection. The first i.v. doses yielded mean serum levels of 93 and 180 micrograms/ml at 5 min after the injection. No tendency toward drug accumulation was observed on multiple dosage. The pharmacokinetics could be described by a linear, open, two-compartment model of drug distribution. The terminal serum half-life (2.1-2.4 h after i.v. doses and 2.6-2.8 h after i.m. doses) remained essentially constant over the period of the study by dose levels. The no-significant differences of areas under the curve between the two routes, at two doses, show the absolute bioavailability of cefoperazone was about 95% following i.m. administration. The high binding to serum proteins (90%) influences favourably the pharmacokinetic parameters of cefoperazone. It yielded high and prolonged serum concentrations and has very useful distribution properties. These favourable properties, together with its good antibacterial activity, suggest that cefoperazone will be effective in treating bacterial infections in human beings.