Comparative pharmacokinetics of cefoperazone following intravenous and intramuscular administration in goats

The pharmacokinetic profile of cefoperazone was studied in goats following intravenous and intramuscular administration of 20mg/kg body weight. Cefoperazone concentrations in serum were determined by microbiological assay technique using Escherichia coli (ATCC 10536) as test organism. Following i.v. administration, the cefoperazone serum concentration–time curve was best fitted in a two compartment open model. Cefoperazone has moderate distribution in the body of goats with Vdss of 0.44±0.03L/kg. The elimination half-life (T0.5(β)), area under curve (AUC) and total body clearance (Cltot) were 1.97±0.14h, 149.63±8.61μgml−1h−1, and 2.17ml/min/kg, respectively. Following i.m. administration, the drug was very rapidly absorbed, with an absorption half-life (T0.5(ab)) of 0.12±0.01h. The maximum serum concentration (Cmax) of 30.42±3.53μgml−1 was attained at (Tmax) 0.58±0.02h, with an elimination half-life (T0.5(el)) of 2.53±0.11h. The systemic bioavailability of cefoperazone in the goats after i.m. administration was 83.62% and in vitro protein binding was 20.34%. The serum concentrations of cefoperazone along 12h post i.m. injection in this study were exceeding the MIC of different susceptible micro-organisms responsible for serious disease problems. Consequently, a suitable intramuscular dosage regimen for cefoperazone was 20mg/kg repeated at 12h intervals in goats. The drug was detected in urine up to 12 and 18h following i.v. and i.m. administration, respectively.